History of metamaterials

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/History_of_metamaterials 

 

A metamaterial which produces a negative index of refraction. The total array consists of 3×20×20 unit cells with overall dimensions of 10×100×100 millimeters.

The history of metamaterials begins with artificial dielectrics in microwave engineering as it developed just after World War II. Yet, there are seminal explorations of artificial materials for manipulating electromagnetic waves at the end of the 19th century. Hence, the history of metamaterials is essentially a history of developing certain types of manufactured materials, which interact at radio frequency, microwave, and later optical frequencies.

As the science of materials has advanced, photonic materials have been developed which use the photon of light as the fundamental carrier of information. This has led to photonic crystals, and at the beginning of the new millennium, the proof of principle for functioning metamaterials with a negative index of refraction in the microwave- (at 10.5 Gigahertz) and optical range. This was followed by the first proof of principle for metamaterial cloaking (shielding an object from view), also in the microwave range, about six years later. However, a cloak that can conceal objects across the entire electromagnetic spectrum is still decades away. Many physics and engineering problems need to be solved.

Nevertheless, negative refractive materials have led to the development of metamaterial antennas and metamaterial microwave lenses for miniature wireless system antennas which are more efficient than their conventional counterparts. Also, metamaterial antennas are now commercially available. Meanwhile, subwavelength focusing with the superlens is also a part of present-day metamaterials research.

Early wave studies

Electromagnetic waves are formed by the vibrations of electric fields and magnetic fields. These fields are perpendicular to one another in the direction the wave is traveling. Once formed, this energy travels at the speed of light until further interaction with matter. The electric field is in a vertical plane and the magnetic field in a horizontal plane. The two types of fields in electromagnetic waves are always in phase with each other.

Classical waves transfer energy without transporting matter through the medium (material). For example, waves in a pond do not carry the water molecules from place to place; rather the wave's energy travels through the water, leaving the water molecules in place. Additionally, charged particles, such as electrons and protons create electromagnetic fields when they move, and these fields transport the type of energy known as electromagnetic radiation, or light. A changing magnetic field will induce a changing electric field and vice versa—the two are linked. These changing fields form electromagnetic waves. Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate. This means that electromagnetic waves can travel not only through air and solid materials, but also through the vacuum of space.

The "history of metamaterials" can have a variety starting points depending on the properties of interest. Related early wave studies started in 1904 and progressed through more than half of the first part of the twentieth century. This early research included the relationship of the phase velocity to group velocity and the relationship of the wave vector and Pointing vector.

In 1904 the possibility of negative phase velocity accompanied by an anti-parallel group velocity were noted by Horace Lamb (book: Hydrodynamics) and Arthur Schuster (Book: Intro to Optics). However both thought practical achievement of these phenomena were not possible. In 1945 Leonid Mandelstam (also "Mandel'shtam") studied the anti-parallel phase and group advance in more detail. He is also noted for examining the electromagnetic characteristics of materials demonstrating negative refraction, as well as the first left-handed material concept. These studies included negative group velocity. He reported that such phenomena occurs in a crystal lattice. This may be considered significant because the metamaterial is a man made crystal lattice (structure). In 1905 H.C. Pocklington also studied certain effects related to negative group velocity.

V.E. Pafomov (1959), and several years later, the research team V.M. Agranovich and V.L. Ginzburg (1966) reported the repercussions of negative permittivity, negative permeability, and negative group velocity in their study of crystals and excitons.

In 1967, V.G. Veselago from Moscow Institute of Physics and Technology considered the theoretical model of medium that known now as a metamaterial. However, physical experimentation did not occur until 33 years after the paper's publication due to lack of available materials and lack of sufficient computing power. It was not until the 1990s that materials and computing power became available to artificially produce the necessary structures. Veselago also predicted a number of electromagnetic phenomena that would be reversed including the refractive index. In addition, he is credited with coining the term "left handed material" for the present day metamaterial because of the anti-parallel behavior of the wave vector and other electromagnetic fields. Moreover, he noted that the material he was studying was a double negative material, as certain metamaterials are named today, because of the ability to simultaneously produce negative values for two important parameters, e.g. permittivity and permeability. In 1968, his paper was translated and published in English. He was nominated later for a Nobel prize.

Later still, developments in nanofabrication and subwavelength imaging techniques are now taking this work into optical wavelengths.

Early electromagnetic media

Bose's apparatus demonstrated at the Royal Institution in 1897. A schematic diagram—the waveguide radiator is affixed on top of the transmitter at left. In addition, a pyramidal electromagnetic horn antenna is first used by Bose. This horn antenna acts as a "collecting funnel" for the electromagnetic radiation of interest.

In the 19th century Maxwell's equations united all previous observations, experiments, and established propositions pertaining to electricity and magnetism into a consistent theory, which is also fundamental to optics. Maxwell's work demonstrated that electricity, magnetism and even light are all manifestations of the same phenomenon, namely the electromagnetic field.

Likewise, the concept of using certain constructed materials as a method for manipulating electromagnetic waves dates back to the 19th century. Microwave theory had developed significantly during the latter part of the 19th century with the cylindrical parabolic reflector, dielectric lens, microwave absorbers, the cavity radiator, the radiating iris, and the pyramidal electromagnetic horn. The science involving microwaves also included round, square, and rectangular waveguides precluding Sir Rayleigh's published work on waveguide operation in 1896. Microwave optics, involving the focusing of microwaves, introduced quasi-optical components, and a treatment of microwave optics was published in 1897 (by Righi).

Jagadish Chandra Bose

Jagadish Chandra Bose was a scientist involved in original microwave research during the 1890s. As officiating professor of physics at Presidency College he involved himself with laboratory experiments and studies involving refraction, diffraction and polarization, as well as transmitters, receivers and various microwave components.

He connected receivers to a sensitive galvanometer, and developed crystals to be used as a receiver. The crystals operated in the shortwave radio range. Crystals were also developed to detect both white and ultraviolet light. These crystals were patented in 1904 for their capability to detect electromagnetic radiation. Furthermore, it appears that his work also anticipated the existence of p-type and n-type semiconductors by 60 years.

For the general public in 1895, Bose was able to remotely ring a bell and explode gunpowder with the use of electromagnetic waves. In 1896, it was reported that Bose had transmitted electromagnetic signals over almost a mile. In 1897, Bose reported on his microwave research (experiments) at the Royal Institution in London. There he demonstrated his apparatus at wavelengths that ranged from 2.5 centimeters to 5 millimeters.

Early chiral media

In 1898, Jagadish Chandra Bose conducted the first microwave experiment on twisted structures. These twisted structures match the geometries that are known as artificial chiral media in today's terminology. By this time, he had also researched double refraction (birefringence) in crystals. Other research included polarization of electric field "waves" that crystals produce. He discovered this type of polarization in other materials including a class of dielectrics.

In addition, chirality as optical activity in a given material is a phenomenon that has been studied since the 19th century. By 1811, a study of quartz crystals revealed that such crystalline solids rotate the polarization of polarized light denoting optical activity. By 1815, materials other than crystals, such as oil of turpentine were known to exhibit chirality. However, the basic cause was not known. Louis Pasteur solved the problem (chirality of the molecules) originating a new discipline known as stereochemistry. At the macroscopic scale, Lindman applied microwaves to the problem with wire spirals (wire helices) in 1920 and 1922.

Karl F. Lindman, from 1914 and into the 1920s, studied artificial chiral media formed by a collection of randomly oriented small spirals. He was written about by present-day metamaterials scientists: Ismo V. Lindell, Ari H. Sihvola, and Juhani Kurkijarvi.

20th century artificial dielectrics

This "lens" converts the input spherical microwave radiation into parallel (collimated) lines in a given direction at the exit side of the microwave lens. The focusing action of the lens is accomplished by the refracting qualities of the metallic strip.

Much of the historic research related to metamaterials is weighted from the view of antenna beam shaping within microwave engineering just after World War II. Furthermore, metamaterials appear to be historically linked to the body of research pertaining to artificial dielectrics throughout the late 1940s, the 1950s and the 1960s. The most common use for artificial dielectrics throughout prior decades has been in the microwave regime for antenna beam shaping. The artificial dielectrics had been proposed as a low cost and lightweight "tool". Research on artificial dielectrics, other than metamaterials, is still ongoing for pertinent parts of the electromagnetic spectrum.

Pioneering works in microwave engineering on artificial dielectrics in microwave were produced by Winston E. Kock, Seymour Cohn, John Brown, and Walter Rotman. Periodic artificial structures were proposed by Kock, Rotman, and Sergei Schelkunoff. There is also an extensive reference list that is focused on the properties of artificial dielectrics in the 1990 book, Field theory of guided waves by R.E. Collin.

Schelkunoff achieved notice for contributions to antenna theory and electromagnetic wave propagation. "Magnetic particles made of capacitively loaded loops were also suggested by Sergei Schelkunoff in 1952 (who was a senior colleague of Winston Kock at Bell Labs at the time). However, Schelkunoff suggested these particles as a means of synthesizing high permeability (and not negative) values but he recognized that such high permeability artificial dielectrics would be quite dispersive."

W.E. Kock proposed metallic and wire lenses for antennas. Some of these are the metallic delay lens, parallel-wire lens, and the wire mesh lens. In addition, he conducted analytical studies regarding the response of customized metallic particles to a quasistatic electromagnetic radiation. As with the current large group of researchers conveying the behavior of metamaterials, Kock noted behaviors and structure in artificial materials that are similar to metamaterials.

He employed particles, which would be of varying geometric shape; spheres, discs, ellipsoids and prolate or oblate spheroids, and would be either isolated or set in a repeating pattern as part of an array configuration. Furthermore, he was able to determine that such particles behave as a dielectric medium. He also noticed that the permittivity "ε" and permeability "μ" of these particles can be purposely tuned, but not independently.

With metamaterials, however, local values for both ε and μ are designed as part of the fabrication process, or analytically designed in theoretical studies. Because of this process, individual metamaterial inclusions can be independently tuned.

With artificial dielectrics Kock was able to see that any value for permittivity and permeability, arbitrarily large or small, can be achieved, and that this included the possibility of negative values for these parameters. The optical properties of the medium depended solely on the particles’ geometrical shape and spacing, rather than on their own intrinsic behavior. His work also anticipated the split-ring resonator, a fabricated periodic structure that is a common workhorse for metamaterials.

Kock, however, did not investigate the simultaneous occurrence of negative values of ε and μ, which has become one of the first achievements defining modern metamaterials. This was because research in artificial materials was oriented toward other goals, such as creating plasma media at RF or microwave frequencies related to the overarching needs of NASA and the space program at that time.

Walter Rotman and R.F. Turner advanced microwave beam shaping systems with a lens that has three perfect focal points; two symmetrically located off-axis and one on-axis. They published the design equations for the improved straight-front-face lens, the evaluation of its phase control capabilities, scanning capabilities, and the demonstrated fabrication techniques applicable to this type of design. Rotman invented other periodic structures that include many types of surface wave antennas: the trough waveguide, the channel waveguide, and the sandwich wire antenna.

Photonic structures

Main article: Photonic crystal

"At frequencies of a few hundred gigahertz and lower, electrons are the principle particles which serve as the workhorse of devices. On the other hand, at infrared through optical to ultraviolet wavelengths, the photon is the fundamental particle of choice." The word 'photonics' appeared in the late 1960s to describe a research field whose goal was to use light to perform functions that traditionally fell within the typical domain of electronics, such as telecommunications, information processing, among other processes. The term photonics more specifically connotes:

• The particle properties of light,
• The potential of creating signal processing device technologies using photons,
• The practical application of optics, and
• An analogy to electronics.

Hence, as photonic materials are used, the photons, rather than electrons, become the fundamental carriers of information. Furthermore, the photon appears to be a more efficient carrier of information, and materials that can process photonic signals are both in use and in further development. Additionally, developing photonic materials will lead to further miniaturization of components.

In 1987 Eli Yablonovitch proposed controlling spontaneous emissions and constructing physical zones in periodic dielectrics that forbid certain wavelengths of electromagnetic radiation. These capabilities would be built into three-dimensional periodic dielectric structures (artificial dielectric). He noted that controlling spontaneous emission is desirable for semiconductor processes.

Exceptional phenomena

Invention of the metamaterial

Historically, and conventionally, the function or behavior of materials can be altered through their chemistry. This has long been known. For example, adding lead changes the color or hardness of glass. However, at the end of the 20th century this description was expanded by John Pendry, a physicist from Imperial College in London. In the 1990s he was consulting for a British company, Marconi Materials Technology, as a condensed matter physics expert. The company manufactured a stealth technology made of a radiation-absorbing carbon that was for naval vessels. However, the company did not understand the physics of the material. The company asked Pendry if he could understand how the material worked.

Pendry discovered that the radiation absorption property did not come from the molecular or chemical structure of the material, i.e. the carbon per se. This property came from the long and thin, physical shape of the carbon fibers. He realized rather than conventionally altering a material through its chemistry, as lead does with glass, the behavior of a material can be altered by changing a material's internal structure on a very fine scale. The very fine scale was less than the wavelength of the electromagnetic radiation that is applied. The theory applies across the electromagnetic spectrum that is in use by today's technologies. The radiations of interest are from radio waves, and microwaves, through infrared to the visible wavelengths. Scientists view this material as "beyond" conventional materials. Hence, the Greek word "meta" was attached, and these are called metamaterials.

After successfully deducing and realizing the carbon fiber structure, Pendry further proposed that he try to change the magnetic properties of a non-magnetic material, also by altering its physical structure. The material would not be intrinsically magnetic, nor inherently susceptible to being magnetized. Copper wire is such a non-magnetic material. He envisioned fabricating a non-magnetic composite material, which could mimic the movements of electrons orbiting atoms. However, the structures are fabricated on a scale that is magnitudes larger than the atom, yet smaller than the radiated wavelength.

He envisioned and hypothesized miniature loops of copper wire set in a fiberglass substrate could mimic the action of electrons but on a larger scale. Furthermore, this composite material could act like a slab of iron. In addition, he deduced that a current run through the loops of wire results in a magnetic response.

This metamaterial idea resulted in variations. Cutting the loops results in a magnetic resonator, which acts like a switch. The switch, in turn, would allow Pendry to determine or alter the magnetic properties of the material simply by choice. At the time, Pendry didn't realize the significance of the two materials he had engineered. By combining the electrical properties of Marconi's radar-absorbing material with his new man-made magnetic material he had unwittingly placed in his hands a new way to manipulate electromagnetic radiation. In 1999, Pendry published his new conception of artificially produced magnetic materials in a notable physics journal. This was read by scientists all over the world, and it "stoked their imagination".

Negative refractive index

In 1967, Victor Veselago produced an often cited, seminal work on a theoretical material that could produce extraordinary effects that are difficult or impossible to produce in nature. At that time he proposed that a reversal of Snell's law, an extraordinary lens, and other exceptional phenomena can occur within the laws of physics. This theory lay dormant for a few decades. There were no materials available in nature, or otherwise, that could physically realize Veselago's analysis. Not until thirty-three years later did the properties of this material, a metamaterial, became a subdiscipline of physics and engineering.

However, there were certain observations, demonstrations, and implementations that closely preceded this work. Permittivity of metals, with values that could be stretched from the positive to the negative domain, had been studied extensively. In other words, negative permittivity was a known phenomenon by the time the first metamaterial was produced. Contemporaries of Kock were involved in this type of research. The concentrated effort was led by the US government for researching interactions between the ionosphere and the re-entry of NASA space vehicles.

In the 1990s, Pendry et al. developed sequentially repeating thin wire structures, analogous to crystal structures. These extended the range of material permittivity. However, a more revolutionary structure developed by Pendry et al. was a structure that could control magnetic interactions (permeability) of the radiated light, albeit only at microwave frequencies. This sequentially repeating, split ring structure, extended material magnetic parameters into the negative. This lattice or periodic, "magnetic" structure was constructed from non-magnetic components.

Hence, in electromagnetic domain, a negative value for permittivity and permeability occurring simultaneously was a requirement to produce the first metamaterials. These were beginning steps for proof of principle regarding Veselago's original 1967 proposal.

In 2000, a team of UCSD researchers produced and demonstrated metamaterials, which exhibited unusual physical properties that were never before produced in nature. These materials obey the laws of physics, but behave differently from normal materials. In essence these negative index metamaterials were noted for having the ability to reverse many of the physical properties that govern the behavior of ordinary optical materials. One of those unusual properties is the capability to reverse, for the first time, the Snell's law of refraction. Until this May 2000 demonstration by the UCSD team, the material was unavailable. Advances during the 1990s in fabrication and computation capabilities allowed these first metamaterials to be constructed. Thus, testing the "new" metamaterial began for the effects described by Victor Veselago 30 years earlier, but only at first in the microwave frequency domain. Reversal of group velocity was explicitly announced in the related published paper.

The super lens

The super lens or superlens is a practical structure based on John Pendry's work describing a perfect lens that can go beyond the diffraction limit by focusing all four fourier components. Pendry's paper described a theoretical novel lens that could capture images below the diffraction limit by employing the negative refractive index behavior. The super lens is a practical realization of this theory. It is a working lens that can capture images below the diffraction limit even though limitations occur due to the inefficiencies of conventional materials. This means that although there are losses, enough of an image is returned to show this work was a successful demonstration.

Invisibility cloak

Ulf Leonhardt was born in East Germany, and presently occupies the theoretical physics chair at the University of St. Andrews in Scotland, and is considered one the leaders in the science of creating an invisibility cloak. Around 1999, Leonhardt began work on how to build a cloaking device with a few other colleagues. Leonhardt stated that at the time invisibility was not considered fashionable. He then wrote a theoretical study entitled "Optical Conformal Mapping". The first sentence sums up the objective: "An invisibility device should guide light around an object as if nothing were there."

In 2005, he sent the paper to three notable scientific journals, Nature, Nature Physics, and Science. Each journal, in turn, rejected the paper. In 2006, Physical Review Letters rejected the paper for publication, as well. However, according to the PRL assessment, one of the anonymous reviewers noted that (he or she ) had been to two meetings in the previous months with John Pendry's group, who were also working on a cloaking device. From the meetings, the reviewer also became aware of a patent that Pendry and his colleagues were supposed to file. Leonhardt was at the time unaware of the Pendry group's work. Because of the Pendry meetings, Leonhardt's work was not really considered new physics by the reviewer and, therefore, did not merit publication in Physical Review Letters.

Later in 2006, Science (the journal) reversed its decision and contacted Leonhardt to publish his paper because it had just received a theoretical study from Pendry's team entitled "Controlling Electromagnetic Fields". Science considered both papers strikingly similar and published them both in the same issue of Science Express on May 25, 2006. The published papers touched off research efforts by a dozen groups to build cloaking devices at locations around the globe, which would test out the mathematics of both papers.

Only months after the submission of notable invisibility cloak theories, a practical device was built and demonstrated by David Schurig and David Smith, engineering researchers of Duke University (October 2006). It was limited to the microwave range so the object was not invisible to the human eye. However, it demonstrated proof of principle.

Transformation optics

The original theoretical papers on cloaking opened a new science discipline called transformation optics.

Development of the nervous system in humans

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Development_of_the_nervous_system_in_humans 

The development of the nervous system in humans, or neural development or neurodevelopment involves the studies of embryology, developmental biology, and neuroscience to describe the cellular and molecular mechanisms by which the complex nervous system forms in humans, develops during prenatal development, and continues to develop postnatally.

Some landmarks of neural development in the embryo include the formation and differentiation of neurons from stem cell precursors (neurogenesis); the migration of immature neurons from their birthplaces in the embryo to their final positions; the outgrowth of axons from neurons and guidance of the motile growth cone through the embryo towards postsynaptic partners, the generation of synapses between these axons and their postsynaptic partners, the synaptic pruning that occurs in adolescence, and finally the lifelong changes in synapses which are thought to underlie learning and memory.

Typically, these neurodevelopmental processes can be broadly divided into two classes: activity-independent mechanisms and activity-dependent mechanisms. Activity-independent mechanisms are generally believed to occur as hardwired processes determined by genetic programs played out within individual neurons. These include differentiation, migration and axon guidance to their initial target areas. These processes are thought of as being independent of neural activity and sensory experience. Once axons reach their target areas, activity-dependent mechanisms come into play. Neural activity and sensory experience will mediate formation of new synapses, as well as synaptic plasticity, which will be responsible for refinement of the nascent neural circuits.

Development of the human brain

Further information: Human embryonic development and Human brain § Development

Highly schematic flowchart of human brain development.

Overview

The central nervous system (CNS) is derived from the ectoderm—the outermost tissue layer of the embryo. In the third week of human embryonic development the neuroectoderm appears and forms the neural plate along the dorsal side of the embryo. The neural plate is the source of the majority of neurons and glial cells of the CNS. A groove forms along the long axis of the neural plate and, by week four of development, the neural plate wraps in on itself to give rise to the neural tube, which is filled with cerebrospinal fluid (CSF). As the embryo develops, the anterior part of the neural tube forms three primary brain vesicles, which become the primary anatomical regions of the brain: the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon). These simple, early vesicles enlarge and further divide into the five secondary brain vesicles – the telencephalon (future cerebral cortex and basal ganglia), diencephalon (future thalamus and hypothalamus), mesencephalon (future colliculi), metencephalon (future pons and cerebellum), and myelencephalon (future medulla). The CSF-filled central chamber is continuous from the telencephalon to the spinal cord, and constitutes the developing ventricular system of the CNS. Because the neural tube gives rise to the brain and spinal cord any mutations at this stage in development can lead to fatal deformities like anencephaly or lifelong disabilities like spina bifida. During this time, the walls of the neural tube contain neural stem cells, which drive brain growth as they divide many times. Gradually some of the cells stop dividing and differentiate into neurons and glial cells, which are the main cellular components of the CNS. The newly generated neurons migrate to different parts of the developing brain to self-organize into different brain structures. Once the neurons have reached their regional positions, they extend axons and dendrites, which allow them to communicate with other neurons via synapses. Synaptic communication between neurons leads to the establishment of functional neural circuits that mediate sensory and motor processing, and underlie behavior.

Neural induction

During early embryonic development the ectoderm becomes specified to give rise to the epidermis (skin) and the neural plate. The conversion of undifferentiated ectoderm to neuro-ectoderm requires signals from the mesoderm. At the onset of gastrulation presumptive mesodermal cells move through the dorsal blastopore lip and form a layer in between the endoderm and the ectoderm. These mesodermal cells that migrate along the dorsal midline give rise to a structure called the notochord. Ectodermal cells overlying the notochord develop into the neural plate in response to a diffusible signal produced by the notochord. The remainder of the ectoderm gives rise to the epidermis (skin). The ability of the mesoderm to convert the overlying ectoderm into neural tissue is called neural induction.

The neural plate folds outwards during the third week of gestation to form the neural groove. Beginning in the future neck region, the neural folds of this groove close to create the neural tube. The formation of the neural tube from the ectoderm is called neurulation. The ventral part of the neural tube is called the basal plate; the dorsal part is called the alar plate. The hollow interior is called the neural canal. By the end of the fourth week of gestation, the open ends of the neural tube, called the neuropores, close off.

A transplanted blastopore lip can convert ectoderm into neural tissue and is said to have an inductive effect. Neural inducers are molecules that can induce the expression of neural genes in ectoderm explants without inducing mesodermal genes as well. Neural induction is often studied in xenopus embryos since they have a simple body pattern and there are good markers to distinguish between neural and non-neural tissue. Examples of neural inducers are the molecules noggin and chordin.

When embryonic ectodermal cells are cultured at low density in the absence of mesodermal cells they undergo neural differentiation (express neural genes), suggesting that neural differentiation is the default fate of ectodermal cells. In explant cultures (which allow direct cell-cell interactions) the same cells differentiate into epidermis. This is due to the action of BMP4 (a TGF-β family protein) that induces ectodermal cultures to differentiate into epidermis. During neural induction, noggin and chordin are produced by the dorsal mesoderm (notochord) and diffuse into the overlying ectoderm to inhibit the activity of BMP4. This inhibition of BMP4 causes the cells to differentiate into neural cells. Inhibition of TGF-β and BMP (bone morphogenetic protein) signaling can efficiently induce neural tissue from human pluripotent stem cells, a model of early human development.

The early brain

Late in the fourth week, the superior part of the neural tube flexes at the level of the future midbrain—the mesencephalon. Above the mesencephalon is the prosencephalon (future forebrain) and beneath it is the rhombencephalon (future hindbrain). The optical vesicle (which will eventually become the optic nerve, retina and iris) forms at the basal plate of the prosencephalon.

The spinal cord forms from the lower part of the neural tube. The wall of the neural tube consists of neuroepithelial cells, which differentiate into neuroblasts, forming the mantle layer (the gray matter). Nerve fibers emerge from these neuroblasts to form the marginal layer (the white matter). The ventral part of the mantle layer (the basal plates) forms the motor areas of the spinal cord, whilst the dorsal part (the alar plates) forms the sensory areas. Between the basal and alar plates is an intermediate layer that contains neurons of the autonomic nervous system.

In the fifth week, the alar plate of the prosencephalon expands to form the cerebral hemispheres (the telencephalon). The basal plate becomes the diencephalon.

The diencephalon, mesencephalon and rhombencephalon constitute the brain stem of the embryo. It continues to flex at the mesencephalon. The rhombencephalon folds posteriorly, which causes its alar plate to flare and form the fourth ventricle of the brain. The pons and the cerebellum form in the upper part of the rhombencephalon, whilst the medulla oblongata forms in the lower part.

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  The embryo's brain at four weeks.

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  Cross-section of a developing spinal cord at four weeks.

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  The embryo's nervous system at six weeks.

Neuroimaging

Neuroimaging is responsible for great advancements in understanding how the brain develops. EEG and ERP are effective imaging processes used mainly on babies and young children since they are more gentle. Infants are generally tested with fNIRS. The MRI and fMRI are widely used for research on the brain due to the quality of images and analysis possible from them.

Magnetic resonance imaging

MRI's are helpful in analyzing many aspects of the brain. The magnetization-transfer ratio (MTR) measures integrity using magnetization. Fractional anisotropy (FA) measures organization using the diffusion of water molecules. Additionally, mean diffusivity (MD) measures the strength of white matter tracts.

Structural magnetic resonance imaging

Using structural MRI, quantitative assessment of a number of developmental processes can be carried out including defining growth patterns, and characterizing the sequence of myelination. These data complement evidence from Diffusion Tensor Imaging (DTI) studies that have been widely used to investigate the development of white matter.

Functional magnetic resonance imaging

fMRI's test mentalising which is the theory of the mind by activating a network. The posterior superior temporal sulcus (pSTS) and temporo-parietal junction (TPJ) are helpful in predicting movement. In adults, the right pSTS showed greater response than the same region in adolescents when tested on intentional causality. These regions were also activated during the "mind in the eyes" exercise where emotion must be judged based on different images of eyes. Another key region is the anterior temporal cortex (ATC) in the posterior region. In adults, the left ATC showed greater response than the same region in adolescents when tested on emotional tests of mentalising. Finally, the medial prefrontal cortex (MPFC) and the anterior dorsal MPFC (dMPFC) are activated when the mind is stimulated by psychology.

Three-dimensional sonography

Higher resolution imaging has allowed three-dimensional ultrasound to help identify human brain development during the embryonic stages. Studies report that three primary structures are formed in the sixth gestational week. These are the forebrain, the midbrain, and the hindbrain, also known as the prosencephalon, mesencephalon, and the rhombencephalon respectively. Five secondary structures from these in the seventh gestational week. These are the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon which later become the lateral ventricles, third ventricles, aqueduct, and upper and lower parts of the fourth ventricle from the telencephalon to the myelencephalon, during adulthood. 3D ultrasound imaging allows in-vivo depictions of ideal brain development which can help tp recognize irregularities during gestation.

White matter development

Using MRI, studies showed that while white matter increases from childhood (~9 years) to adolescence (~14 years), grey matter decreases. This was observed primarily in the frontal and parietal cortices. Theories as to why this occurs vary. One thought is that the intracortical myelination paired with increased axonal calibre increases the volume of white matter tissue. Another is that synaptic reorganization occurs from proliferation and then pruning.

Grey matter development

The rise and fall of the volume of grey matter in the frontal and parietal lobes peaked at ~12 years of age. The peak for the temporal lobes was ~17 years with the superior temporal cortex being last to mature. The sensory and motor regions matured first after which the rest of the cortex developed. This was characterized by loss of grey matter and it occurred from the posterior to the anterior region. This loss of grey matter and increase of white matter may occur throughout a lifetime though the more robust changes occur from childhood to adolescence.

Neuronal migration

Neuronal migration is the method by which neurons travel from their origin or birthplace to their final position in the brain. Their most common means of migration are radial and tangential migration.

Radial migration

Neural stem cells proliferate in the ventricular zone of the developing neocortex. The first postmitotic cells to migrate from the preplate which are destined to become Cajal-Retzius cells and subplate neurons. These cells do so by somal translocation. Neurons migrating with this mode of locomotion are bipolar and attach the leading edge of the process to the pia. The soma is then transported to the pial surface by nucleokenisis, a process by which a microtubule "cage" around the nucleus elongates and contracts in association with the centrosome to guide the nucleus to its final destination. Radial fibres (also known as radial glia) can translocate to the cortical plate and differentiate either into astrocytes or neurons. Somal translocation can occur at any time during development.

Subsequent waves of neurons split the preplate by migrating along radial glial fibres to form the cortical plate. Each wave of migrating cells travel past their predecessors forming layers in an inside-out manner, meaning that the youngest neurons are the closest to the surface. It is estimated that glial guided migration represents 80-90% of migrating neurons.

Axophilic migration

Many neurons migrating along the anterior-posterior axis of the body use existing axon tracts to migrate along in a process called axophilic migration. An example of this mode of migration is in GnRH-expressing neurons, which make a long journey from their birthplace in the nose, through the forebrain, and into the hypothalamus. Many of the mechanisms of this migration have been worked out, starting with the extracellular guidance cues that trigger intracellular signaling. These intracellular signals, such as calcium signaling, lead to actin and microtubule cytoskeletal dynamics, which produce cellular forces that interact with the extracellular environment through cell adhesion proteins  to cause the movement of these cells. Neurophilic migration refers to the migration of neurons along an axon belonging to a different nerve. Gliophilic migration is the migration of glia along glial fibres.

Tangential migration

Most interneurons migrate tangentially through multiple modes of migration to reach their appropriate location in the cortex. An example of tangential migration is the movement of Cajal-Retzius cells within the marginal zone of the cortical neuroepithelium.

Others

There is also a method of neuronal migration called multipolar migration. This is seen in multipolar cells, which are abundantly present in the cortical intermediate zone. They do not resemble the cells migrating by locomotion or somal translocation. Instead these multipolar cells express neuronal markers and extend multiple thin processes in various directions independently of the radial glial fibers.

Neurotrophic factors

Neurotrophic factors are molecules which promote and regulate neuronal survival in the developing nervous system. They are distinguished from ubiquitous metabolites necessary for cellular maintenance and growth by their specificity; each neurotrophic factor promotes the survival of only certain kinds of neurons during a particular stage of their development. In addition, it has been argued that neurotrophic factors are involved in many other aspects of neuronal development ranging from axonal guidance to regulation of neurotransmitter synthesis.

Adult neural development

Main articles: Neuroregeneration and Adult neurogenesis

Neurodevelopment in the adult nervous system includes mechanisms such as remyelination, generation of new neurons, glia, axons, myelin or synapses. Neuroregeneration differs between the peripheral nervous system (PNS) and the central nervous system (CNS) by the functional mechanisms and especially, the extent and speed.

The nervous system continues to develop during adulthood until brain death. For example:

• physical exercise has neurobiological effects
• the consumption of foods (or nutrients), obesity, alterations of the microbiome, drinks, dietary supplements, recreational drugs and medications may possibly also have effects on the development of the nervous system
• various diseases, such as COVID-19, have effects on the development of the nervous system
  • For example, several genes have been identified as to being associated with changes in brain structure over lifetime and are potential Alzheimer's disease therapy-targets.
• psychological events such as mental trauma and resilience-building
• exposure to environmental pollution and toxins such as air pollution may have effects on the further development of the nervous system
• other activities may also have effects on the development of the nervous system, such as lifelong learning, retraining, and types of media- and economic activities
• broadly, brain aging

Research, treatments and policies often distinguish between "mature" brains and "developing" brains while scientists have pointed out that "the complex nature of neurodevelopment itself poses challenges to establishing a point of reference that would indicate when a brain is mature" and that various structural brain measures change constantly throughout the adult phase of life, albeit childhood neuroplasticity-levels may not be reached again and it is thought that there are various critical and sensitive periods of brain development.

Research

Spatio-temporal modeling of brain development

In early development (before birth and during the first few months), the brain undergoes more changes in size, shape and structure than at any other time in life. Improved understanding of cerebral development during this critical period is important for mapping normal growth, and for investigating mechanisms of injury associated with risk factors for maldevelopment such as premature birth. Hence, there is a need for dense coverage of this age range with a time-varying, age-dependent atlas. Such a spatio-temporal atlases can accurately represent the dynamic changes occurring during early brain development, and can be used as a normative reference space.

Furthermore, large scale gene expression studies of different brain regions from early gestation to aging have been performed. This kind of data provides a unique insight into changes that happen in brain during this long period. This approach showed that 86 per cent of the genes were expressed, and that 90 per cent of these were differentially regulated at the whole-transcript or exon level across brain regions and/or time. The majority of these spatio-temporal differences were detected before birth, with subsequent increases in the similarity among regional transcriptomes. Furthermore, interareal differences exhibit a temporal hourglass pattern, dividing the human neocortical development into three major phases. During the first phase, in the first six months after conception, general architecture of brain regions is largely formed by a burst of genetic activity, which is distinct for specific regions of the neocortex. This rush is followed by a sort of intermission beginning in the third trimester of pregnancy. During this period, most genes that are active in specific brain regions are quieted — except for genes that spur connections between all neocortex regions. Then in late childhood and early adolescence, the genetic orchestra begins again and helps subtly shape neocortex regions that progressively perform more specialized tasks, a process that continues into adulthood.

Specific regions

Research has been able to make new discoveries for various parts of the brain thanks to the noninvasive imaging available.

• Medial Prefrontal Cortex (MPFC)

In this region, more activity is noted in adolescents than in adults when faced with tests on mentalising tasks as well as communicative and personal intent. Decreased activity from adolescence to adulthood. In a mentalising task employing animation, the dMPFC was more stimulated in adults while the ventral MPFC was more stimulated in children. They can be attributed to the use of objective strategy associated with the dMPFC. Theories for decrease in activity from adolescence to adulthood vary. One theory is that cognitive strategy becomes more automatic with age and another is that functional change occurs parallel to neuroanatomical change which is characterized by synaptogenesis and pruning.

The MPFC is an example of one specific region that has become better understood using current imaging techniques. Current research provides many more findings like this.

Early life stress

Early life stress is defined as exposure to circumstances during childhood that overwhelm a child’s coping resources and lead to sustained periods of stress. Results from multiple studies indicate that the effects of early life stress on the developing brain are significant and include, but are not limited to the following: increased amygdala volume, decreased activity in frontal cortical and limbic brain structures, and altered white matter structures.

Early life stress is believed to produce changes in brain development by interfering with neurogenesis, synaptic production, and pruning of synapses and receptors. Interference with these processes could result in increased or decreased brain region volumes, potentially explaining the findings that early life stress is associated with increased amygdala volume and decreased anterior cingulate cortex volume.

From the literature, several important conclusions have been drawn. Brain areas that undergo significant post-natal development, such as those involved in memory and emotion are more vulnerable to effects of early life stress. For example, the hippocampus continues to develop after birth and is a structure that is affected by childhood maltreatment. Early life stress seems to interfere with the overproduction of synapses that is typical in childhood, but does not interfere with synaptic pruning in adolescence. This results in smaller hippocampal volumes, potentially explaining the association between early life stress and reduced hippocampal volume. This volume reduction may be associated with the emotion regulation deficits seen in those exposed to early life stress.

The amygdala is particularly vulnerable to early life stress. The amygdala also undergoes significant development during childhood, is structurally and functionally altered in individuals that have experienced early life stress, and is associated with the socioemotional difficulties linked with early life stress.

Receptor type is another consideration when determining whether or not a brain region is sensitive to the effects of early life stress. Brain regions with a high density of glucocorticoid receptors are especially vulnerable to the effects of early life stress, likely because glucocorticoids bind to these receptors during stress exposure, facilitating the development of survival responses at the cost of other important neural pathways. Some examples of brain regions with high glucocorticoid receptor density are the hippocampus and cerebellar vermis. Stress activates the HPA axis, and results in the production of glucocorticoids. Increased glucocorticoid production results in increased activation of these brain regions, facilitating the development of certain neural pathways at the cost of others.

Abnormalities in brain structure and function are often associated with deficits that may persist for years after the stress is removed, and may be a risk factor for future psychopathology. The brain regions most sensitive to early life stress are those undergoing developmental changes during the stress exposure. As a result, stress alters the developmental trajectory of that brain region, producing long-lasting alterations in structure and function.

Common types of early life stress that are documented include maltreatment, neglect, and previous institutionalization. Living in poverty has also been shown to similarly influence brain function.

Community radio

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Community_radio 

 

KRBX Radio Boise volunteers during the station's Spring Radiothon in 2013—direct community support is critical for such local media.

Community radio is a radio service offering a third model of radio broadcasting in addition to commercial and public broadcasting. Community stations serve geographic communities and communities of interest. They broadcast content that is popular and relevant to a local, specific audience but is often overlooked by commercial or mass-media broadcasters. Community radio stations are operated, owned, and influenced by the communities they serve. They are generally nonprofit and provide a mechanism for enabling individuals, groups, and communities to tell their own stories, to share experiences and, in a media-rich world, to become creators and contributors of media.

In many parts of the world, community radio acts as a vehicle for the community and voluntary sector, civil society, agencies, NGOs and citizens to work in partnership to further community development aims, in addition to broadcasting. There is legally defined community radio (as a distinct broadcasting sector) in many countries, such as France, Argentina, South Africa, Australia and Ireland. Much of the legislation has included phrases such as "social benefit", "social objectives" and "social gain" as part of the definition. Community radio has developed differently in different countries, and the term has somewhat different meanings in the United Kingdom, Ireland, the United States, Canada and Australia, where freedom of speech laws and de facto realities differ.

Contents

• 1 Vision, philosophy, and status
  • 1.1 Conceptions of community in the literature
  • 1.2 Models
• 2 By country
  • 2.1 Australia
  • 2.2 Austria
  • 2.3 Bangladesh
  • 2.4 Benin
  • 2.5 Bolivia
  • 2.6 Brazil
  • 2.7 Canada
  • 2.8 Ecuador
  • 2.9 Ethiopia
  • 2.10 Guatemala
  • 2.11 Hungary
  • 2.12 India
    • 2.12.1 Content Exchange and Knowledge Sharing for community radio
  • 2.13 Ireland
  • 2.14 Japan
  • 2.15 Jordan
  • 2.16 Philippines
  • 2.17 Nepal
  • 2.18 New Zealand
  • 2.19 South Africa
  • 2.20 Solomon Islands
  • 2.21 South Korea
  • 2.22 Sweden
  • 2.23 Syria
  • 2.24 Thailand
  • 2.25 United Kingdom
  • 2.26 United States
• 3 UNESCO
• 4 International
• 5 See also
• 6 References
• 7 Further reading
• 8 External links

Vision, philosophy, and status

Modern community radio stations serve their listeners by offering a variety of content that is not necessarily provided by the larger commercial radio stations. Community radio outlets may carry news and information programming geared toward the local area (particularly immigrant or minority groups who are poorly served by major media outlets). Specialized musical shows are also often a feature of many community radio stations. Community and pirate stations (in areas where they are tolerated) can be valuable assets for a region. Community radio stations typically avoid content found on commercial outlets such as Top 40 music, sports and "drive-time" personalities. A meme used by members of the movement is that community radio should be 10 percent radio and 90 percent community. This means that community radio stations should focus on getting the community talking and not solely on radio (which is a technological process); the social concerns of community radio are stressed over radio per se. There is also a distinction drawn in contrast to mainstream stations, which are viewed as pandering to commercial concerns or the personalities of presenters.

Conceptions of community in the literature

Communities are complex entities, and what constitutes the "community" in community radio is subject to debate which varies by country. "Community" may be replaced by terms such as "alternative", "radical" or "citizen" radio. In sociology, a "community" has been defined as a group of interacting people living in a common location.

Community radio has been built around the ideals of access and participation. Stations have been run by locals, typically to serve a local audience. However, the internet's availability and popularity has encouraged many stations to podcast and/or stream and audio and make it available globally.

Models

Two philosophical approaches to community radio exist, although the models are not mutually exclusive. One emphasizes service and community-mindedness, focusing on what the station can do for the community. The other stresses involvement and participation by the listener.

In the service model locality is valued; community radio, as a third tier, can provide content focused on a more local or particular community than a larger operation. Sometimes, though, providing syndicated content not already available within the station's service area is viewed as public service. Within the United States, for example, many stations syndicate content from groups such as Pacifica Radio (such as Democracy Now!) on the basis that it provides content not otherwise available (because of a program's lack of appeal to advertisers—in Pacifica's case, due to its politically controversial nature).

In the access (or participatory) model, the participation of community members in producing content is viewed as a good in itself. While this model does not necessarily exclude a service approach, there is some disagreement between the two.

By country

Australia

Community radio station & newspaper office side by side in regional (Young), New South Wales

Community broadcasting is Australia’s third media sector, formally represented by the Community Broadcasting Association of Australia (CBAA). In January 2012, there were 359 licensed community radio stations (including remote indigenous services). A 2002 report found that 20,000 Australians (or 0.1 percent of the population) were involved as volunteers in the community radio sector on a regular basis, and volunteers account for more than $145 million in unpaid work each year. Nationally, more than 7 million Australians (or 45 percent of people over 15) listen to community radio each month.

The role of community broadcasting in Australia, according to CBAA, is to provide a diverse range of services meeting community needs in ways unmet by other sectors. Community broadcasting is sustained by the principles of access and participation, volunteerism, diversity, independence and locality.

Community radio stations may be specialized music stations, represent local music and arts or broadcast talks and current-affairs programs representing alternative, indigenous Australian, environmental, feminist or gay and lesbian interests (filling perceived gaps in commercial or government radio content). 53 percent of community radio stations serve an array of communities of interest, including indigenous and ethnic groups, people with a print disability, young people, older people, the arts/fine music, religious, and the gay and lesbian communities. The remaining stations provide a service which may be described as generalist: addressing the interests of communities in particular areas, but also addressing a range of specialized interests.

Community broadcasting, more than any other form of media in Australia, shapes and reflects the national character in all its diversity. The sector is unique in its capacity to provide fresh programming by and for indigenous, ethnic and RPH communities. Community broadcasting stations have a strong commitment to local news and information, the promotion of local and national music, arts and culture and providing training in media skills.

When a not-for-profit community group applies to the regulating body (the Australian Communications and Media Authority) for a community broadcasting licence, it specifies the community interest it intends to serve. Licensees are selected by the regulator on the basis of suitability and on the merits of the licence application and the capacity to serve identified community interests. Upon grant of a five-year renewable licence each station is required to continue to serve the community interest for which the licence was granted. The Broadcast Services Act establishes the requirement to continue to represent the licensed community of interest and the requirement to encourage participation from the licensed community of interest in the provision and selection of programs as key conditions of the licence. Provisions for Temporary Community Radio Licences in the Act allow, where spectrum is available, for aspirant community groups to develop their facilities and financial and programming models before the regulator considers making a permanent licence available.

Austria

Main article: Alliance of Community Radio Austria

In Austria, community radio was introduced in 1990 through a pirate radio movement. Regular licensed broadcasts began in 1998. Commercials are not permitted, so stations are primarily operated as non-profit NGOs. There are 14 community radio stations operating in the country.

Bangladesh

Workshop for Bangladesh NGOs Network for Radio and Communications staffs

Bangladesh NGOs Network for Radio and Communication (BNNRC) has been struggling for the last 12 years to open up the community media (including Community Radio, Community Television and Community film) and giving focus on its vital role as voices of the voiceless people. BNNRC has been addressing the community radio & community TV access issue for over a decade, almost since its emergence in the year 2000.

BNNRC is in special consultative status with the United Nations Economic and Social Council. BNNRC has been promoting advocacy to the government in relation to community radio with other organizations since its emergence in 2000.

The objective of BNNRC's Community Radio intervention is to address social issues (such as poverty and social exclusion) at the community level, empower marginalized rural groups and catalyze democratic processes and ongoing development efforts.

At the moment, positive and supportive condition is prevailing in our country. Because; Bangladesh Government has already acknowledged the importance of community radio and announced the Community Radio Installation, Broadcast and Operation Policy. Bangladesh is the 2nd country in South Asia in formulating policy for Community Radio. Now 14 community radio stations are on-air in the country, aiming to ensure empowerment and right to information for the rural community. They are broadcasting altogether 120 hours program per day on information, education, local entertainment and development motivation activities. Around 536 youth women and youth are now working with those Stations throughout the country as rural broadcasters.

The prime role of community radio is giving a voice to people who do not have access to mainstream media to express their views on community development. Promoting the right to communicate, expediting the process of informing the community, assisting the free flow of information and acting as a catalyst of change are major tasks achievable by community radio. It also upholds creative growth and democratic spirit at the community level.

As a result, the Ministry of Information of the People's Republic of Bangladesh announced the Community Radio Installation, Broadcast and Operation Policy 2008. Under this policy, the Ministry of Information approved 14 community radio stations for the first time in Bangladeshi history. To ensure the free flow of information to the people, the government enacted the Right to Information Act 2009. Community radio stations are a strong step in empowering rural people.

The reality of today is that the bondage between the community people and local-level community radio stations are getting strengthened day-by-day. Community Radio has now become their part of life. Community Radio becomes the instrument for the livelihood battle of the rural people.

BNNRC established the Community Media News Agency (CMNA), Community Media Academy (CMA) and Monthly Community Media to share development news and building capacity for the Community Media sector in Bangladesh. BNNRC now started advocacy with the Government of Bangladesh to open up community television for development.

Ministry of Information approved 17 community Radio in Bangladesh:

• Community Radio Sagor Giri 99.2 Young Power in Social Action (YPSA) for Sitakunda, Chittagong
• Community Radio Nalta 99.2 [Nalta Community Hospital (Satkhira)]
• Community Radio Mukti 99.2 [LDRO (Bogra)]
• Community Radio Pollikontho 99.2 [BRAC (Moulivi Bazer)]
• Barandro Community Radio 99.2 (Naogaon)
• Community Radio Mahananda 98.8 [Proyas (Chapai Nababgonj)]
• Community Radio Padma 99.2 [CCD (Rajshahi)]
• Community Radio Jhinuk 99.2 [Srizoni (Jhinaidhah)]
• Community Radio Bikrampur 99.2 [Ambala Foundation] (Munshiganj)
• Community Radio Lokobetar 99.2 [MMC (Barguna Sadar Upazila)]
• Community Radio Chilmari 99.2 [ Chilmari, RDRS (Kurigram)]
• Community Radio Sundarban 98.8 Koyra Upazila (Khulna)
• Community Radio Naf 99.2 Teknaf [ACLAB (Cox's Bazar District)
• Community Rural Radio 98.8 [Agriculture Information Services (AIS) Community Rural Radio (Barguna District)]
• Community Radio Meghna 90.0, Charfassion, Bhola [COAST Trust (Bhola District)
• Community Radio SagarDwip 99.2, Hatyia Island, [Dwip Unnayan Shongstha-DUS (Noakhali District)
• Community Radio Sarabela 98.8, ([SKS Foundation Gaibandha District)
• Community Radio Boral 99.2 (Bagha, Rajshahi District)

Earlier, in the 1st batch on 22 April 2010, Ministry of Information has approved 14 community radio stations, the number stands on 16 by adding more 2 stations in the line soon. 14 community radio stations ushered a new era by rural broadcasting 106 hours programs daily within a listeners’ community of 4.6 million of 13 upazila of the country. These programs reflect the rights and scopes of the disadvantaged community people. This neo-media has produced a neo-generation of community radio broadcasters at rural level where a total of 536 youth and youth women are contributing creativity their time, effort and thus taking part in nation-building process. The initiating organizations received approval for primary set up of community radio stations in the 2nd phase are:

• [Progati Research on Grassroots Ownership and Traditional Initiative for Shaymnagar Upazila, Satkhira District]
• [Aparajeyo Bangladesh for Pirganj Upazila, Rangpur District]
• [Bangla-German Sampreeti (BGS) for Tangail District]
• [SKS Foundation for Sader of Gaibandha District]
• [Voluntary Association for Rural Development (VARD) for Sunamganj District]
• [Somaj-O-Jati Gathan(SOJAG) for Dhamrai Upazila of Dhaka District]
• [Shechashebi Bahumukhi Mahila Samajkallyan (SBSSS) for Boalia Upazila of Rajshahi District]
• [Jyoti Development Foundation for Sadar Upazila of Kushtia District]
• [Institute of Development Affairs (IDEA) for South Surma, Sylhet District]
• [Nazrul Smriti Sangsad (NSS) for Kalapara Upazila of Patuakhali District]
• [Karmojibi Nari for Bheramara Upazila of Kushtia District]
• [Bandhan Society for Halimpur, Bajithpu Upazila, Kishoreganj District]
• [Patuakhali Development Organization (PDO) for Bauphal Upazila of Patuakhali]
• [Coastal Association for Social Transformation for Sadar Upazila of Cox’s Bazer]
• [Program for Eco-Social Development (PESD) for Sherpur Upazila, of Bogra District ]
• [Borendra Unnayan Prochasta for Sapura Upazila of Rajshahi]

Bangladesh NGOs Network for Radio and Communication represents the community media sector to Government, Industry, Regulatory Bodies, Media and Development Partners in Bangladesh. The reality of today is that the bondage between the community people and local-level community radio stations are getting strengthened day-by-day. Community Radio has now become their part of life. Community Radio becomes the instrument for the livelihood battle of the rural people.

BNNRC has been struggling for the last 12 years to open up the community media (including Community Radio, Community Television and Community film) and giving focus on its vital role as voices of the voiceless people and has already established the Community Media News Agency (CMNA), Community Media Academy (CMA) and Monthly Community Media to share development news and building capacity for the Community Media sector in Bangladesh.

Community radio is considered an alternative, effective mass media for the rural disadvantaged population to express their thoughts in their own voice and their own style.

Benin

Radio is the primary mass medium in Benin and sub-Saharan Africa. Of its 55 radio stations, 36 are community stations with programming ranging from news and sports to music and quiz shows. Although there is a need for such stations, it is difficult for them to succeed due to financial and structural problems and a lack of funding.

Bolivia

A well-known example of community radio in Bolivia was the tin miners' radio. Funded by trade union dues and operated mainly at the local and regional level, there were more than 25 such radio stations between 1960 and 1985. Changes in government policy eliminated many unionised mining jobs after 1985 and some radio stations were sold or ceased to exist. In spite of many difficulties, five stations continue to broadcast.

La Voz del Minero, Radio Pío XII, RadioVanguardia de Colquiri, Radio Animas, Radio 21 de Diciembre, and Radio Nacional de Huanuni were some of the most important radio stations created, funded and managed by Bolivian mining workers. In 1949, a station began broadcasting in the mining district of Catavi. During the next 15 years, other districts followed; they bought the equipment, trained young people from their villages, and the workers funded the stations with a percentage of their salaries.

Most of the radio stations began small, with simple equipment. A few received foreign support and evolved into more sophisticated stations, with better equipment. Several built theatres next to their stations, so union meetings could be broadcast live; for example, Radio Vanguardia had a theatre decorated with large murals narrating the story of the Colquiri mining centre. One scene on a mural depicts the attack by Bolivian Air Force planes in 1967 (when the country was under military rule).

During the early 1970s 26 radio stations were in operation, all in the mining districts of the highlands. At the time, the miners' unions in Bolivia were still powerful and considered among the most politically advanced in Latin America. In times of peace and democracy the miners' radio stations were integrated into the daily life of the community, becoming an effective replacement for telephone and postal service. People would receive their mail through the stations and post messages, which were read several times during the day: calls for a meeting of women from the Comité de Amas de Casa (Housewives' Committee); messages from union leaders about their negotiations with the government in the capital; messages of love between young people; the announcement of a new play by the Nuevos Horizontes theater group (often staged on the platform of a big truck, with workers illuminating the scene with their own lamps); and announcements of sport activities, burials, births and festivities.

In times of political upheaval, the union radio stations would become the only trustworthy source of information. As the military captured newspapers, radio and TV stations in the capital and other cities, the only information available would come from the miners' radio stations. They would join the cadena minera ("mining chain") until the army penetrated the mining camps and mounted an assault on the stations, which were defended (sometimes to the death) by the workers. A film by Bolivian filmmaker Jorge Sanjinés, The Courage of the People, reenacts the attack on the mining district of Siglo XX by the army in June 1967. Another film, a documentary by Alfonso Gumucio Dagron and Eduardo Barrios entitled Voices of the Mine and produced by UNESCO, describes their political and social importance. The miners' radio stations would air reports on the political situation; they would also link for live transmissions when an important sporting or cultural event took place in the mining district. Other than that, each station was fully independent of the others.

The miners' radio stations were important because of the importance of mining in Bolivia; Bolivian miners were also influential because for several decades they had a powerful means to communicate their ideas. As the importance of mining in Bolivia declined during the 1980s, the unions were weakened and some of the radio stations disappeared (along with their mining districts).

Brazil

Princesa FM of Ponta Grossa, southern Brazil an example of CR. As indicated the frequency is 87.9 MHz, one of the most common tunings intended for this type of radio in this country.

Law No 9612/1998 defines a community radio station as sound stations belonging to non-profit foundations or associations representing a public contained therein, living in a neighborhood or united by a social cause and that the station presents itself as a spokesperson of these people. It has to operate with a maximum power of 25 watts ERP and its tower will have the limit of 30 meters. These technical characteristics delineate a portion coverage of an urban area, a partial coverage in the municipality. As said, the community broadcaster has a cultural function, there can be no explicit commercial breaks but cultural supports of the content of the grid. Programming times can not be sold to third parties and broadcasting to other stations is prohibited (going against the idea of a "community radio").

They should be open to divergent opinions and divergent lifestyles regarding each of them. The average radius of reach is 1 km (covering a village and a neighborhood in particular). The use for the ideological-political end or to present a specific belief is not allowed. An entity that has interest can send the documents to the Statement of Interest Register (CDI). The requests received appeared in the National Grant Plan (PNO), later a notice will be opened with the documents that should be sent. This does not mean that the institution has obtained the radiofrequency, there will be a selection process to eliminate the competition. Even if after all it is authorized, it will have to be countersigned 90 days until the release of the National Congress, otherwise the applicant may require a provisional license.

The FM frequencies reserved for the service are 87.5 MHz, 87.7 MHz and 87.9 MHz, however, in some regions of Brazil, community radio stations are reserved in the frequencies 98.3 MHz, 104.9 MHz, 105.9 MHz, 106.3 MHz and 107.9 MHz. The frequency is reserved and licensed only by Anatel, the National Telecommunications Agency of Brazil.^[15] The history of the Brazilian community is inclusive in a context of Brazilian redemocratization in the second half of the 1980s. In the struggle to institute the same, a movement began in 1991, organizing itself in the form of a forum, in 1994 the judiciary gave a vowable vote to the establishment of radios and their proponents to become legal. The largest city in the country, São Paulo because of the lack of frequency, managed to regulate these radio stations only in 2007 through a public notice. Currently are about 34 stations of the genre operating only in 87.5 MHz (different from the frequencies commonly used).

On July 10, 2018, the Federal Senate Plenary approves the power increase from 25 watts to 150 watts, the effective half of a local commercial radio. The senator and author of the bill said it will improve coverage in rural areas where homes are more dispersed. However Anatel may interfere and determine the maximum power that can be transmitted, especially when there are adjacent CRs. The former minister Gilberto Kassab ordered to extinguish on the eve of 2019 more than 130 community radios for irregularities. Minas Gerais was the one that most lost emisoras (27) followed by São Paulo (20), another 22 states lost 1 CR for each one.

It is the most common type of radio broadcasting in Brazil. By 2014 there were 4641 broadcasters, 47% of all radios, being twice the commercial + educational FM and the triple of medium-wave broadcasters.

Canada

See also: List of community radio stations in Canada

Community radio stations in Canada often target commercially underserved minority-language communities such as Franco-Ontarians, Acadians, Anglo-Quebecers or First Nations. These stations are often volunteer-run and operated by cooperatives or other not-for-profit corporations. In larger cities, community-oriented programming more commonly airs on campus radio stations, although some cities do have community radio stations as well. Most English-language community stations in Canada are members of the National Campus and Community Radio Association, or NCRA, while most of Canada's French language community radio stations are members of either the Association des radiodiffuseurs communautaires du Québec (ARCQ) or the Alliance des radios communautaires du Canada(ARC).

The province with the largest number of community radio stations in Canada is Saskatchewan. The majority of those stations are affiliated with Missinipi Broadcasting Corporation, an aboriginal public radio network. Community stations are subject to the Canadian Radio-television and Telecommunications Commission's (CRTC) community radio policy.

In this policy, the CRTC requires community stations to

• facilitate community access to programming;
• promote the availability of training throughout the community; and
• provide for the ongoing training and supervision of those within the community wishing to participate in programming.

It also requires stations to offer diverse programming that reflects the needs and interests of the community, including:

• music by new and local talent;
• music not generally broadcast by commercial stations;
• spoken word programming; and
• local information.

The CRTC maintains a list of community stations. In Canada, call letters and frequencies are regulated by Industry Canada’s Spectrum Management.

The CRTC classifies community radio stations as one of two types, with slightly different regulatory requirements. Most stations are classified as "Type B"; however, a community radio station which operates as the sole local media service serving its community — such as an English language community radio station in Quebec, a First Nations radio station or a community radio station in a small town with no other local radio stations at all — is classified as "Type A", granting it a more flexible set of regulatory and license requirements to accommodate the wider range of community programming interests that such a station needs to serve.

Ecuador

In Ecuador, many community radio stations are operated by religious groups and include Catholic, Protestant and Baháʼí Faith stations. The amount of community participation and self-management varies. Radio Latacunga was associated with a project in which indigenous organizations were supplied with simple equipment to record weekly programs for broadcast in the early morning. Some indigenous groups operate their own radio stations; these include the Shuar Federation in the tropical rainforest, and the community of Simiatug in Bolívar Province. Unlike in Bolivia, trade-union radio has historically not been influential in Ecuador.

Ethiopia

Ministry of Communication and Information Technology (MCIT), Federal Republic of Ethiopia and World Development Foundation, New Delhi, India signed an agreement on 30 June 2014 for establishing seven Community Radio Stations at Finote Selam, Dilo (Borana), Adola Rede (Guji), Chewaka (Illubabor Zone|Illubabor), Semera, Ari Woreda (Debub Omo) and Uba Debretsehay (in Gamo Gofa zone, Southern Nations, Nationalities and People Region), Ethiopia to serve as an avenue for the free flow of beneficial information aimed at uplifting the plight of the various sectors of the community. The stations were planned to open up possibilities for everyone, especially regular citizens, to express themselves socially, culturally, politically and spiritually, thus preparing each and every member of the community to participate in decision-making.

World Development Foundation, with an active support of different agencies of Government of India and Embassy of India in Ethiopia and especially HE Mr. Sanjay Verma, Ambassador and Mr. Vijay Kumar, Dr. Hari Om Srivastava and MCIT, Ethiopia was able to complete the job and hand over all the Community Radio Stations to MCIT in September 2015.

CRS at Finote Salem

Milestones

• Signing of Agreement: 30 June 2014
• Opening of Letter of Credit: 28 October 2014
• Dispatch of Material from India/USA/Italy/Spain: Between Dec2014 to Feb 2015.
• Receipt of material by MCIT and handing over to WDF for installation: June 2015
• Installation and Commissioning at seven sites by WDF and handing over to MCIT: 28 June 2015 to 5 September 2015
• Training of Officers/operational staff: 21 September 2015 to 25 September 2015

Highlights

• The emphasis has been on using type design for Lay Out, identical equipment and installation to ease the maintenance and procurement of spares. This will also allow the exchange of staff and development of expertise.
• The objective for training was to provide:
• full range of WDF accredited training on the usage of the equipment, hardware and software, programming including hands on training.
• simplified processes for equipment maintenance by the broadcaster’s trainees in order to maintain the equipment’s good working condition
• Programming basics and use of Community Radio Station for social, cultural, political and spiritual upliftment of people in the region
• Two local engineers were involved all through the installation.(Grateful to MCIT, Ethiopia)

Achievements Through its regular operations the community radio shall be able to:

• provide a development forum for the community;
• encourage participatory community development;
• promote active involvement of underprivileged groups such as women and young people;
• intensify the sharing of information within the community;
• encourage innovation in community development;
• increase the free flow of accurate and balanced information to, and within, the community;
• provide a forum for local cultural expression; and improve people’s access to information in local languages

The Mediaction Foundation together with the Jimma Community and the Jimma University realized the first community radio station in Ethiopia in 2007. The Community radio station is located in Jimma University (in the south-west of Ethiopia).

Guatemala

• There are more than 100 community radio stations operating in Guatemala, but the indigenous communities don't have explicit rights to use radio frequencies, though their right to exist is guaranteed by the country's Peace Accords.
• Many believe the lack of support for community radio puts the volunteers in a very vulnerable position, and the law puts freedom of expression at risk.

Hungary

The first community stations began as pirates, broadcasting political free-speech and music programs after the change from socialism. Tilos Rádió in 1991 was the first such station, followed by Fiksz Rádió and Civil Rádió. Since 2004 a new category arose: kisközösségi (small community stations), which are low-power stations. By 2010, more than 70 such microstations have begun broadcasting throughout the country. There are village stations, small-town stations, university stations, subcultural and religious stations. In Budapest Cool FM, Első Pesti Egyetemi Rádió and Fúzió Rádió are small community stations.

India

Union Minister for Information and Broadcasting, Mrs. Ambika Soni inaugurating the Community Radio Station, at Punjab University, in Chandigarh on February 13, 2011

In India the campaign to legitimise community radio began in the mid-1990s, soon after the Supreme Court of India ruled in its judgment of February 1995 that "airwaves are public property". The judgment inspired several free speech advocates, academics and community members across the country to being a concerted campaign to legitimize community radio in India.

In 1996, a Bangalore-based media advocacy group called VOICES organized a gathering of community radio stakeholders. A declaration calling for the establishment of a third tier of broadcasting, i.e., community broadcasting, was signed. A suggestion that AIR's local stations should allocate regular airtime for community broadcasting was put forward. Requests were also made for grant of licences to NGOs and other non-profit making groups for running community radio stations. Subsequently, UNESCO made available a portable production and transmission "briefcase radio station" kit to VOICES to do experimental broadcasts of programmes for a hands-on learning experience towards the objective of setting up an independently run community radio station.

A UNESCO sponsored workshop, hosted by an Andhra Pradesh NGO, Deccan Development Society (DDS) from July 17–20, 2000 in Hyderabad issued the 'Pastapur Initiative' on community radio that urged the government to take its intentions of freeing broadcasting from state monopoly to its logical conclusion, by making media space available not only to private players but also to communities. This landmark document urged the government to create a three-tier structure of broadcasting in India by adding non-profit community radio to the already existing state-owned public radio and private commercial radio.

Simultaneously, several initiatives had already started working on community radio in terms of production and dissemination of participatory programming. In South India, Deccan Development Society worked with Dalit women's collectives to start Sangam Radio, the programmes for which were made by the community, but were 'narrowcast', i.e. played back to the community over cassette players at group meetings. Another landmark initiative was jointly set up by VOICES and MYRADA - called Namma Dhwani (Our Voices), where programmes were produced by communities in and around the village of Budikote (about 100 kilometers from Bangalore), and were distributed over the nearest All India Radio station and subsequently over the local cable network. In the west, Kutch Mahila Vikas Sanghatan, a civil society group in Gujarat worked with the women in Kutch District to produce programmes on local developmental and cultural issues, and started broadcasting on the nearest All India Radio Station. In the northern part, Alternative for India Development made programmes with community members in Garhwa block of Jharkhand, and broadcast programmes over the Daltonganj All India Radio Station. Community Groups in Chamba, and Rudraprayag, both in Uttarakhand started producing participatory programmes and broadcast over the World Space Satellite Radio network. Kumaon Vani radio station was set up by The Energy and Resources Institute in March 2010 in Nainital district of Uttarakhand with the aim of bringing together communities across several villages in the Kumaon region. It was established to use radio as a tool to promote sustainable development among the local farming community. It broadcasts content that is relevant to the people of the area that is overlooked by commercial media.

By early 2003, the government of India released the first set of community radio guidelines drafted by Dr. Hari Om Srivastava and also the technology to be used, but unfortunately, restricted eligibility to educational institutions only. Marginalized and voiceless communities continued to remain outside the ambit of the then released community radio policy guidelines. Anna FM was India's first campus "community" radio station. And, as per the latest Community Radio Policy Guidelines (2006), Anna FM falls well within the definition of Community Radio. Launched on 1 February 2004, it is run by the Education and Multimedia Research Centre (EM²RC). Programmes are produced by students as well as community. Anna university station was launched on 1 February 2004 . Commonwealth of learning and UNESCO sponsored an international meet on community radio at Anna university in December 2004 . All the applicants to CR in India as well as representatives from 13 countries attended. Government of India studied the working of this station along with the change of ruling party in India Several of the lessons learnt at Anna CR were incorporated in the Policy document in 2006. Practitioners and community radio advocates continued to push the government towards expanding the mandate of the community radio sector to include communities living in rural, remote and hilly areas of the country.

On 16 November 2006, the government of India implemented new Community Radio Guidelines, which permit NGOs, educational institutions and agricultural institutions to own and operate community radio stations. By 30 November 2008, there were 38 operational community radio stations in the country. Of these, two are run by NGOs and the rest by educational institutions.

The first community-based radio station licensed to an NGO (as distinct from campus-based radio) was launched on 15 October 2008, when Sangham Radio, licensed to Deccan Development Society, in Pastapur village, Medak district, Andhra Pradesh state went on the air at 11:00 am. Therefore, Sangham Radio, based on the policy guidelines, is second community radio station of India. Sangham Radio, which broadcasts on 90.4 MHz, is licensed to the Deccan Development Society (DDS) (an NGO which works with women's groups in approximately 75 villages in Andhra Pradesh). The community radio station is managed by "General" Narsamma and Algole Narsamma.

Under the 2006 community radio policy, any not-for-profit "legal entity"—except individuals, political parties (and their affiliates), criminal and banned organizations—can apply for a CR license. The licence entitles them to operate a 100-watt (Effective Radiated Power) radio station, with a coverage area of approximately a 12-km radius. A maximum antenna height of 30 meters is allowed. Community radio stations are expected to produce at least 50 percent of their programmes locally, as much as possible in the local language or dialect. The stress is on developmental programming, although there is no explicit ban on entertainment. News programmes are banned on community radio in India (as they are on commercial FM radio). However, the government has clarified that certain categories of news are permitted on radio, including sports news and commentaries, information on traffic and weather conditions, coverage of cultural events and festivals, information on academic events, public announcements pertaining to utilities such as electricity and the water supply, disaster warnings and health alerts. Five minutes of advertising per hour is allowed on community radio. Sponsored programs are not allowed, except when the program is sponsored by the government at the local or state level.

In a given license area, the Wireless Planning and Coordination (WPC) wing of the MoCIT reserves only three frequencies for community radio. This reservation is informally done and the WPC does not have any official communication or guidelines with respect to spectrum allocation for community radio in the FM band. The WPC follows a channel separation of 800 kHz in India. This means that if a radio station is allotted 90.4 MHz in a given license area, then the next available frequency is 91.2 MHz. Further, once a radio station is allotted a frequency by the WPC, that particular frequency is blocked for a radius of 100 kilometers.

Activists and community workers from across the country have banded together under the aegis of the Community Radio Forum of India to coordinate training and support for community radio stations, and to work for a more proactive community radio policy. The Community Radio Forum, India, was registered as a Society and Trust on 26 February 2008. Members from the Community Radio Forum participate in screening committee meetings to screen potential applicants, and the organization is also recognized as a national level self-regulatory body in the Draft Broadcast Bill as published by the Government of India.

By 1 July 2010, the Ministry of Information and Broadcasting announced that 715 applications for CR licenses had been received, including 104 under the old campus-radio guidelines. 231 Letters of Intent were issued (including 63 under the old guidelines). Grant of Permission Agreements were signed with 102 applicants, and 68 community radio stations were on the air. 107 applications were rejected, and 377 applications were being processed. By 1 February 2012, the Ministry of Information and Broadcasting had received a total of 991 community radio licence applications. Grant of Permission Agreements had been signed with 161 applicants and 126 community radio stations were on air.

From April 1, 2012, the Ministry of Communications and IT has hiked the spectrum fees to Rs. 91,000 - a fivefold increase from the previous annual fee of Rs. 19,700. This move provoked widespread protest from functional community radio stations, advocacy bodies like Community Radio Forum and Community Radio Association of India, and even the Secretary, Ministry of Information and Broadcast has gone on record to say that his Ministry's views were not sought before the decision was taken. He also expressed concern that many organizations would find it impossible to pay the increased spectrum royalty charges. The Community Radio Forum has already boycotted one policy consultation held by the Ministry of Information and Broadcasting, on 9th and 10 May. Several community radio stations also observed a 'Day of Silence' on 9 May, where the spectrum fee hike was announced, protest songs were broadcast, community views were invited, and transmission was switched off for the rest of the day. After pressure from various stakeholders, the Ministry for Information and Communication Technology (MoCIT) announced that the spectrum fee and royalty charges would be rolled back to annual fee of Rs. 19,700. The spectrum fee was Rs. 19,700 annually, till September 2013, at which time the Ministry was to re-examine the matter.

According to the Ministry of Information and Broadcasting, Government of India, the status on 25 April 2013 of Community Radio in India was:

• No. of applications received so far, from 2004 to 05 Feb 2013 (including 104 under 2002 CR Guidelines): 1200
• Letters of Intent (LOI) issued: 428
• Grant of Permission of Agreement (GOPA) signed: 191
• Operational Community Radio Stations: 148
• Number of applications rejected: 545
• Applications under process: 227

The complete list of operational community radio stations in India is published on the website of the Ministry of Information and Broadcasting. Additionally, Jose Jacob, of the National Institute of Amateur Radio in Hyderabad has also published a list of available stations.

To see details and descriptions on each of the individual operational community radio stations, the Ministry of Information and Broadcasting prepares a compendium on Community radio, which is also available and published on their website.

Community Radio and Commonwealth Educational Media Centre for Asia (CEMCA): from 2007 onwards, with CEMCA being the implementing agency and DR R Sreedher as its director, the Ministry of Information and Broadcasting, Government of India organized more than 40 awareness workshops throughout the country to create an atmosphere for getting more organisations to apply for a license for CR. By June 2012, the government had received more than one thousand applications and 400 of them got the Letters of intent LOI. While the initial phase saw more stations in educational campuses an analysis of the 400 LOIs brings out the fact that two thirds of the LOIs have gone to civil society organisations. They find it difficult to launch the station, due to lack of funds, training, human resources and the difficulty in getting the frequency cleared by the WPC wing of the Ministry of Telecommunications. In July 2014, Government of India announced a scheme to support community radio stations and allocated ₹100 crore for this purpose.

Community Radio Association Community Radio Association was formed soon after the first Sammelan of CR stations in 2011 in Delhi. 58 stations expressed their interest in April 2011 for the formation of an association, wherein people working on the ground, can represent their communities and bring the voices of the voiceless to the fore. A paper was prepared and circulated among operational stations and a consensus on the role of the association, its structure, objectives etc. were arrived at. A society was registered in Delhi in July 2011, under the Societies Registration Act.

The salient features of the CRA are:

• Only representatives of functional CR stations are its voting members
• It has been registered as an All India Body with 12 members from nine different states signing the MOA
• CRA works in a decentralized manner with Zonal and State Chapters. Each Chapter is empowered to organize workshops, events in line with CRA’s objectives.

Even though CRA is only two years old its contribution and the role of its members in building an environment in favour of community Radio has been substantive.

CRA has been organizing events/workshops and has been sharing the experiences of its members across the globe. Some of its members have been representing the movement in international forums and reiterating the power of the Community radio. They have been supporting the growth of this movement in countries of both Europe and Africa.

Since CRA is a member-based organisation, all its members have been running community radio stations, in diverse regions and dialects, together they bring to the table a mine of resources and experience.

The strength of CRA is its network of experienced radio practitioners, who manifest the mandate of the Community Radio. This organisation is a true reflection of India’s diversity, the multitude of languages and dialects, the varied topography and history. It is the only network in this sector, which is totally democratic and allows space for dissent, as there is nothing homogeneous about any community.

If we try to total up the experience of each member radio station- which are now 92 in all, then it would amount to a huge figure. The reach of this radio station together is to over 4 million people.

In 2013, CRA has organized two zonal workshops – South and West Zones and three state level experience sharing meets – Tamil Nadu, Maharashtra, Kerala. There have been workshops and meetings in all the zones, wherein members have come together and shared their challenges and achievements.

With a mission to promote, encourage, support and facilitate all functional and desirous Community Radio Stations in India and abroad, CRA has already hosted seven workshops for the Ministry of Information and Broadcasting. The seven Community Radio Awareness workshops were held at Dibrugarh, Ooty, Goa, Faridabad, Bhubaneswar, Kochi and Jaipur. The participation of the desirous Community Radio Operators was tremendous. The quality and content of the workshops was well thought out, and inspiring. Over 90 percent of the participants gave Letters of Intent on the last day.

CRA led the entire campaign against the rise in the licence fee. Members of the organisation met with the Minister, Mr Kapil Sibbal, personally and handed over the petition that was signed by all its members. CRA worked closely with CRF on this issue, and also organised a meeting with the then Minister of Information and Broadcasting, Ms Ambika Soni, who took up the issue of the hike in fees with the concerned department. Besides this:

• Members of CRA, have been part of the working paper on the Community Radio Support Fund, and contributed extensively to the process.
• CRA members are part of the screening committee for new stations.
• CRA Members are also part of the Technical committee for Community Radio Support Scheme (CRSS) and their suggestions and inputs have been considered valuable.
• CRA members were also the pioneers in developing a proposal for the incorporation of a Community Radio Peer Review to strengthen and support the operations of already existing community radio stations through cross learning and sharing. CRA member are also involved in the CR Policy review discussions.
• Individual members of CRA have worked in various capacities as facilitators, mentors, trainers for other organizations involved in the CR space namely, CEMCA, Ministry of Science and Technology, UNESCO.
• CRA is working on different training modules for capacity building in CR and disaster management, sustainability, knowledge sharing, mobilizing communities for health care, collaboration on non-formal learning and education programmes.
• CRA member stations have also won awards for their work in integrating technology with Community Radio and several ongoing research are being conducted on the same
• CRA member stations have been invited as speakers to several national and international forums like Bangladesh Community Radio Forum (25–27 February 2012), Asia-Pacific Institute for Broadcasting Development (AIBD) 2012, Asia Media Summit (29 May 2012), Cyprus Community Media Center, Nocosia (January 28, 2013, Radiodays Europe radio conference in Berlin 18–19 March 2013, International Association of Women in Radio and Television, seminar on Community Radio and Democracy in South Asia (5 March 2013)

Content Exchange and Knowledge Sharing for community radio

Indian government has been promoting content exchange especially radio programmes, good practices, case studies etc. to facilitate meaningful utilisation of available resources.

In past two years, Ministry of Information and Broadcasting has promoted EK duniya anEK awaaz (Edaa) - which is an audio and knowledge exchange portal for Community Radio practitioners in South Asia. Launched in year 2008, Edaa is completing 5 years on 1 September 2013.

Edaa is a web-based service that uploads the content of radio stations. Listening to Bhojpuri or Tamil from villages that don't appear even on Google maps, is such an exciting platform that even the ministry mentions this in its press release on future plans for Community Radio. Edaa is South Asia's biggest community-produced audio bank and hosts more than 2,900 radio programmes in 28 different South Asian languages categorised under 33 thematic areas. Another online space that supports learning and knowledge exchange between Community Radio stations in India is the Community Media Manch Platform  This platform supports collaborations, knowledge sharing and webinars that community radio stations and members of community media can undertake to share their experiences.

Ireland

Ireland has had self-described community radio stations since the late 1970s, although it was not until 1995 that the first 11 licensed stations went on the air as part of an 18-month pilot project run by the Independent Radio and Television Commission. Early stations were represented by the National Association of Community-Radio Broadcasters, which in 1988 published a guide to setting up new stations.

There are 24 licensed stations in Ireland. In 2004 the licensed stations formed a co-operative CRAOL as a representative group in 2004, with the stations as shareholders. In 2007, new membership categories were created for aspiring stations, and a "Development Ladder" established to aid new stations in their development. By 2010, there were 42 aspiring stations at various stages of development. The Broadcasting Act 2009 provided a legal definition of community radio, which previously had been determined by the Community Radio Policy of the Broadcasting Commission of Ireland (now the Broadcasting Authority of Ireland). The Act also provided for the availability of a 100-day licence (within a 12-month period) for aspiring groups who meet the legal definition.

An Agreement for Mutual Co-operation was established in 2008 by CRAOL; this ensures that the signatories (which include all fully licensed stations) share successful funding applications, training materials and policies. This has led to a significant increase in networking and information-sharing. The agreement also covered the sharing of programming, and a network website facilitates these activities through a resource bank and online programme exchange.

Community radio stations in Ireland encompass stations serving a geographic community or a community of interest (such as campus stations, Christian and Irish-language stations). Accredited training in Community Radio has been available through CRAOL since 2004. The pace of such training has increased since mid-2009, with 95 percent of CRAOL member stations involved. In June 2010 the first Community Radio Conference was held in Croke Park, Dublin. Stations are located in all four provinces of Ireland; however, coverage is not universal. Dublin has the largest number of stations, and there are significant clusters in north and west Connaught and mid-Munster.

Community radio in Ireland encompasses:

• Process: Participation by communities in creation of programming
• Product: Service provided to the community through programming supplied

The combination of process and product is determined by the needs of the community, and implemented through a management structure controlled by the community.

Japan

Japan has a network of low-power community radio stations across the country. Their most common call sign is JOZZ-XXX-FM.

It was institutionalized in 1992. 1995 Great Hanshin earthquake and later, the number of broadcasting stations has increased. Currently (September 2015), about 300 stations exist.

Jordan

The first community radio AmmanNet.net was established in 2000 in Jordan on the internet by award-winning Arab journalist Daoud Kuttab as a means of bypassing government restrictions on private, non-governmental radio. In 2005 AmmanNet was licensed as an FM private station in Jordan's capital, Amman. The radio paid US$30,000 for a licence. AmmanNet has also been involved in the training of two other community radio stations in Jordan: one in the twin villages of Lib and Mleih, and another as part of King Hussein University in the southern city of Ma'an. AmmanNet is also involved in training Arab media activists in internet radio. A program was begun to train personnel and launch nine Gulf-based radio stations as part of khaleejnet.net. In January 2008, the name of AmmanNet radio was changed to Al-Balad radio while AmmanNet.net remained as a news website.

Two other community radio stations have been established in Jordan. Yarmouk FM is located at Yarmouk University in Irbed as part of the school's Journalism and Mass Communications program. Farah FM is under construction, but has a license to broadcast in Amman and Zarqa (Jordan's second-largest city). This station will focus primarily on youth and women's issues.

Philippines

Main article: Radyo Natin Network

The best-known community radio network in the Philippines is Radyo Natin (Our Radio). Its stations nationwide broadcast a live Manila feed via satellite; sometimes stations air local programming, cutting the Manila feed. It is considered a community network, because local programs air on different RN stations. Radyo Natin is owned by the Manila Broadcasting Company.

Radyo Natin is the largest network of community radio stations in the Philippines, counting over 150 small FM stations throughout the archipelago from Batanes in the north to Tawi-Tawi in the south. RN stations are owned and operated by franchise holders, who are public-service-oriented communicators in their own right. With audio streaming, it is possible for the national feed to reach listeners all over the world via the internet; it is hoped that in the near future (as of 2011), the franchise stations will also be heard worldwide. Radyo Natin is able to reach audiences that have never been reached before by radio.

Although Radyo Natin is found in the FM band, in the mornings it affiliates with Manila Broadcasting Company’s flagship station, DZRH, for national news programming. During the afternoons, Radyo Natin features popular music.

With its studios at the MBC Building in the Star City Complex in Pasay, Radyo Natin sends its signals to its stations by satellite. These stations, in turn, rebroadcast its signals locally. These individual Radyo Natin stations can, however, "unhook" from the Manila central studios and air events in their own areas at specified times; thus, Radyo Natin is nationwide in coverage but local in nature.

In 2005 a show-cause order containing a cease-and-desist directive from the commissioner of the National Telecommunications Commission was issued to Radyo Natin, forcing the closure of all stations. In the order against Manila Broadcasting Company, NTC Commissioner Ronald Olivar Solis said that the company is "operating a low power FM station as a commercial broadcasting station without the necessary authority from the Commission."

Nepal

Radio Chapakot, a community radio of Nepal

Nepal adopted community radio in 1997 when Radio Sagarmatha (Sagarmatha is the Nepalese name for "Mount Everest"), broadcasting on 102.4 MHz, became the first independent public-interest broadcaster in South Asia. It was established by the Nepal Forum of Environmental Journalists (NEFEJ) in May of that year. Radio Sagarmatha is in the front lines of the fights for freedom of expression and the right to information of Nepalese citizens.

As of 2011, there are more than 150 community radio stations which have been licensed by the Nepalese government. In Nepal, there are no separate policies or laws for community radio. The existing policy and applies to both community and commercial radio stations. Community radio stations have been petitioning the government to introduce different policy and law for community radio stations, whose mottoes are social change and social justice. They have played a role in restoring democracy and changing Nepal to a republic from a monarchy. The rule of law, gender equality, education, health, civics, anti-corruption initiatives, good governance, the environment and day-to-day problems and issues are examined in a different format by the local community radio stations. Community radio enjoys good coverage throughout Nepal, and news is one of its most popular formats. Its first Radio Producer/presenter was Mr. Ghamaraj Luitel, who served Radio Sagarmatha holding different positions in programme and top management for nearly one and one-half decades. He made Radio Sagarmatha very popular through unique radio programmes among its listeners during his 15 years service and left it after playing vital role to develop it as Station Manager for four years. Mr. Luitel led Radio Sagarmatha during the King Gyanendra's coup to save independent radio movement playing a role as central spokesperson after February 1, 2005.

Radio Sagarmatha's history is interwoven with the gradual loosening of government control over the airwaves in Nepal. From the time of the new constitution in November 1990, the drive to put the station on the air was instrumental in bringing about a new communications environment and a new awareness of the importance and need for independent, public-interest broadcasting.

Mass media in Nepal face barriers; the geography of the country is ill-suited to either mass-circulation print media or coverage by electronic media. Access to newspapers, radio, television and education is limited by poverty; Nepal has a low literacy level, particularly in rural areas and among women. Both print and electronic media are concentrated in urban centers like Kathmandu and are thought to have limited relevance for rural people.

In 1990, Nepal changed from a monarchical non-party system to a parliamentary model. A new constitution enshrined the right to freedom of expression (specifically, the right of every citizen to demand and receive information on any matter of public importance). The expression of basic communication rights in the constitution was followed by more focused policy and practical guidelines: in 1992, a National Communications Policy; in 1993, a National Broadcasting Act and in 1995, broadcast regulations.

Before 1994 radio broadcasting was the exclusive domain of Radio Nepal, the state broadcaster established during the early 1950s. Even after 1990, state governments were slow in relinquishing monopoly control of radio broadcasting. The first independent license was granted in 1997, four-and-a-half years after the initial application. The battle for this license was long, hard-fought and significant. The main obstacles were an unstable political environment, conservative politicians and bureaucrats disinclined to change and the monolithic presence of Radio Nepal. Between October 1992 (when the application was registered) and May 1997 (when the license was granted), Nepal had four different governments, four ministers and four secretaries of communication. Waged primarily by journalists committed to the cause of free expression and public-interest broadcasting, the fight involved figures of national prominence, professional associations, NGOs, the print media, foreign embassies, UN organizations, and INGOs.

From the outset the main organization vehicle for Radio Sagarmatha (for both the campaign to get a license and to establish a radio station) has been the Nepal Forum of Environmental Journalists, a non-governmental organization and association of journalists. Key international supporters during the establishment phase were UNESCO and DANIDA.

NEFEJ is the current license-holder of Radio Sagarmatha, although the station was officially a joint effort and partnership with three other media-based NGOs: the Himal Association, Worldview Nepal and the Nepal Press Institute. The station was headed by a seven-member board of directors, constituted by NEFEJ. Through NEFEJ bylaws, the board had representation from all four partner NGOs and met monthly to review and plan activities, set policy and provide direction for the station.

In April 1999, Radio Sagarmatha operated with the following staff: a station manager, six full-time producers, two technicians, a music librarian, an engineer, an accountant and an assistant. The station also benefited from the contributions and experience of international supporters. Volunteers are an important part of Radio Sagarmatha's programming and operation. The station's programming has given many people the opportunity to have their voices and opinions heard in a public forum. On a daily basis, the station takes listeners into everyday life. The variety of voices and sounds (and its less-than-state-of-the-art equipment) gives the station a different tone from other broadcasters in the region: one of real life, as lived and programmed by real people. Interviewees and those profiled on the station come from a variety of backgrounds and occupations.

Radio Sagarmatha works to present listeners with "a human package": a combination of issues and entertainment, social discussions and music, and a conduit for the variety of voices and opinion previously unheard on Nepal's radio channels. In its programming, the station's difference from the state broadcaster and the growing number of Western-style commercial stations is most evident. Public-affairs journalism and broadcasting are at the heart of Radio Sagarmatha's mission and vision for a more responsible press and a more pluralistic society. With a long tradition of folk media and a rich musical heritage, cultural programming is also prominent in the station's six-hour daily broadcast.

Other aspects of programming include an initiative named "Safa Radio: The Clean Air Campaign" in which the station works with the Nepal Environmental Scientific Society to measure air pollution in Kathmandu and broadcasts information about the capital's air quality. Though prohibited at first from broadcasting news, the station airs summaries of daily news stories in a format mixed with music and broadcasts daily community-news programs. Community access is an important part of programming. There is a daily feature, It's My Turn Now (in which individuals from the community voice their opinions), vox populi segments, listeners' letters and feedback recorded by telephone. In late 1998, Radio Sagarmatha formed a partnership with the BBC World Service; 30 minutes of the BBC Nepali service and 30 minutes of world news in English are heard in, respectively, the evening and morning programme blocks. A full list of stations can be found on the website of the Association of Community Radio Broadcasters Nepal.

New Zealand

Main article: Association of Community Access Broadcasters

The Association of Community Access Broadcasters (ACAB) is a group of 11 New Zealand community radio stations. The stations, established between 1981 and 2000 and receiving government funding since 1989, broadcast community programming and provide facilities, training and on-air time for individuals and community groups to produce the programming.

The ACAB group is a core component of New Zealand On Air's Community Broadcasting Strategy. A government funding pool of approximately $2 million is allocated annually for the 11 stations to produce programming for women, youth, children, ethnic and other minorities and people with disabilities in accordance with section 36(c) of the Broadcasting Act 1989. Individual station funding is allocated on a four-tier system based on audience reach, with each station receiving between $110,000 and $220,000. In return for government funding, ACAB stations have an individual and collective mandate to broadcast programmes for people of a wide range of particular religions, cultures, languages, ages and sexualities. Stations operate independently and locally, making decisions on programming and scheduling by consensus.

South Africa

Main article: Community radio in South Africa

Shortly after the end of World War II, the country's repressive state policies gave the SABC (South African Broadcasting Corporation) an effective monopoly. For nearly half a century it was the only broadcaster permitted to operate, and faced no independent radio competition on South African territory until the early 1990s' transition to democracy. The first legally permitted, non-SABC broadcast was that of 1991's "Festival Radio" from the campus radio studios at Rhodes University in Grahamstown. An Independent Broadcast Authority was created to oversee the opening of the country's airwaves, with small community radio stations being permitted to broadcast for the first time. Applications were discussed in open session, to ensure transparency and accountability. Notable early community broadcasters included Bush Radio in Cape Town and Radio Unitra in Umtata. The Independent Communications Authority (ICASA) now regulates (as of 2011) the telecommunications and broadcasting sectors.

Solomon Islands

The Solomon Islands have a number of community FM radio stations established under a United Nations Development Programme in Isabel Province. In March–June 2009 these were used to strengthen women and youth networking under a peace-building project of the Commonwealth of Learning. The stations are linked to rural email stations of the People First Network. The Don Bosco Technical School has also assisted the Tetere community in operating a radio station near Honiara, and the Solomon Islands Development Trust established a Community Media Centre to expand local capacity.

Soweto has only 1 Community Radio Station called Jozi Fm 105.80 FM. It first went on air in 1995 as Bua Community Station and it was later named Jozi Fm. It is now led by Mr Mpho Mhlongo who is a former presenter and one of the founders of the station.

South Korea

The South Korean government licensed several low-power community radio stations in 2005. Maximum power is one watt, which covers 5 km.

Sweden

See also: Partial list of community radio stations in Sweden

In Sweden, community radio (Swedish: närradio) was introduced in 1978 with test transmissions; regular broadcasts began the following year. Commercials were not permitted until 1993, but stations are primarily operated as non-profit NGOs. There are 150 community radio stations in the country.

Syria

ARTA FM is the first community radio station in Syria broadcasting in three languages: Kurdish, Syriac and Arabic. It was established on 07.06.2013 in Amudah and it has offices in Amudah and Qamishli in Syria.

Thailand

Community radio in Thailand grew quickly during the government of Prime Minister Thaksin Shinawatra, taking advantage of a delay in the establishment of a regulatory authority. Thailand's 2,000 to 3,000 community radio stations (often operating unlicensed) have been accused of causing interference with air-traffic-control and other radio stations. However, selected community radio stations have been the target of police crackdowns, causing critics to accuse the government of political interference.

United Kingdom

The Broad Eye Windmill, home of Windmill Broadcasting

 

Main article: Community radio in the United Kingdom

In the UK, the idea of community-based services can be traced back at least as far as the original concept for BBC local radio in the early 1960s. Thereafter, various land-based unlicensed pirate radio stations (such as East London Radio and Radio AMY: Alternative Media for You) developed the idea further. As pirate stations proliferated during the late 1970s and early 1980s, these stations were joined by those broadcasting specifically to minority immigrant communities (such as the Afro-Caribbean and Asian communities, particularly in cities such as London, Birmingham, Bristol, Gloucester and Manchester). Although "community radio" remains synonymous with "pirate radio" for some people in the UK, most minority immigrant stations focused purely on specific musical genres and were operated (theoretically at least) on a for-profit basis. Community radio services in the UK are operated on a not-for-profit basis, with community ownership and control built into their structure.

Community radio stations were in operation on cable systems from 1978 onwards; mostly situated in new-town areas, they were operated by volunteers. Notable stations included Radio Thamesmead (later RTM Radio) in southeast London, one of the first cable radio stations in the UK, which began on the Rediffusion cable system in the southeast London area in 1978. During the late 1980s and early 1990s, the newly formed Radio Authority awarded licences (termed "Incremental" by the outgoing Independent Broadcasting Authority) to a number of new, ex-pirate and cable-based community ventures. The old breed of community radio stations could raise funds by selling airtime and by receiving donations or grants.

Following an experiment of Access Radio licensed by the former UK broadcast regulator the Radio Authority, legislation was brought to create a new tier of community radio regulated by the RA's successor OFCOM. The first station to go on air under this new scheme was 103 The Eye which launched on 1 November 2005, serving the Vale of Belvoir on the Leicestershire/Nottinghamshire border on 103 FM and on the internet. Since 2005 some 300 such stations have been licensed by broadcasting regulator Ofcom operating on five-year licences with the opportunity to renew at the end of each term. Most community radio stations in the UK are on FM, typically at a power of 25 watts. FM community radio stations include Andover Radio, Cambridge 105, Chiltern Voice FM, Preston FM and Penistone FM. A few community radio stations broadcast on AM (medium wave), particularly in rural areas, and some operate online, like Windmill Broadcasting, the UK's only radio station broadcasting from a Windmill, in the Broad Eye Windmill, Stafford.

With the introduction of SS-DAB (small-scale Digital Audio Broadcasting licences) from Ofcom, a new breed of community radio stations will launch on DAB in towns and cities around the UK. Stations, such as Blyth's South Beach Radio are piloting their formats with web streams in preparation for a DAB launch when the licences become available.

United States

Main article: List of community radio stations in the United States

In the U.S., community radio stations are non-profit, community-based operations licensed by the Federal Communications Commission. These stations differ from other public radio outlets in the U.S. by allowing community volunteers to actively participate as broadcasters.

In the U.S., community radio stations generally have smaller budgets than National Public Radio (NPR) network outlets, due to the smaller audiences attracted by their diversified programming and in turn, the small number of potential contributors and business supporters. Community stations are distinct from NPR stations in that most community-radio programming is locally produced by non-professional disc jockeys and producers, whereas traditional public stations rely on programming from NPR and other outlets (such as PRI). However, some community stations, such as KVNF in Colorado and WDIY in Pennsylvania, carry NPR in addition to their volunteer-based local origination programming.

Parade at the launch of WXOJ-LP, Valley Free Radio, in Northampton, Massachusetts in August 2005

Many community stations are licensed as full-power FM stations, while others, particularly those founded after 2005, are licensed under low-power broadcasting rules. Many of the former were founded in the 1960s and 1970s when cultural experimentation (such as the New Left) in the U.S. had a significant following, while others were influenced by the philosophy of radio activist Lorenzo Milam. Community radio stations are usually overseen by non-profit organizations, which are led boards of directors and often include paid staff for managing business operations and coordinating volunteers. Community radio programming involving volunteers is also offered as part of student-run stations at colleges, universities and in some cases, high schools.

The National Federation of Community Broadcasters was formed in 1975 as a membership organization for community radio stations. NFCB publishes handbooks for stations, hosts an annual conference and lobbies on behalf of community radio at the federal level. It was criticized in the 1990s for perceptions it advocated homogenization of programming. The organization has changed leadership since this period. The Grassroots Radio Coalition is a loose network of stations which formed as a reaction against increasing commercialization of public radio and lack of support for volunteer-based stations.

UNESCO

UNESCO is a strong supporter of community radio and works to increase the viability of local radio stations around the world. In 2001, the Media Development and Society Section produced the “Community Radio Handbook” to share best practices collected through the Organization’s involvement in the sector. This handbook specifically gives recommendations to radio station personnel in how to engage listeners in democratic debate as a means to forward community development.

The Organization has also supported community radio through the direct training of radio station staff. The “Empowering Local Radio with ICTs” project strengthened the reporting capacities of 59 local radio stations from 2012 to 2018. This UNESCO project was implemented in 10 countries of Sub-Saharan Africa, including Burundi, the Democratic Republic of the Congo, Kenya, Lesotho, Namibia, Rwanda, South Africa, Tanzania, Uganda and Zambia. Workshops focused on improving the quality of broadcasts, building widespread correspondent networks and promoting sustainability.

Gender sensitivity training was another important aspect of the project, with many of the best stories pertaining to gender issues being amalgamated in the “On air with rural women” exhibition, opening the celebrations for International Women’s Day 2018 and being showcased at the 2018 European Development Days.

International

The worldwide association for free radios is the World Association of Community Radio Broadcasters (AMARC).