Difference between revisions of "FM Microbroadcasting & LPFM Radio Equipment"
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Revision as of 11:11, 22 May 2015
Low Power FM (LPFM) radio service
The FCC launched the low power FM service in 2000 after grassroots pressure demanded community control of the airwaves. The service is entirely commercial-free, and licenses were only granted to nonprofit organizations. Low power FM stations can operate at a maximum power of 100 watts, which generally provides coverage within three to five miles.
Unfortunately, as the FCC was starting to license new stations, Congress put a hault to it after a lobbying campaign by corporate broadcasters, which restricted new licensing opportunities.
NPR - National Public Radio was one major opponent trying to stop LPFM.
The Communications Act of 1934 replaced the FRC with the broader Federal Communications Commission (FCC), noting that their role was to“regulate the public airwaves in the public interest,” but still offering no specific requirements for soliciting the public’s input.
The first well-known micro-broadcaster was Mbanna Kantako, who used a 1 watt transmitter to broadcast to his neighbors in a Springfield, Illinois housing project starting in 1987. Kantako used his radio station to discuss police brutality and other issues affecting his neighborhood. Kantako refused to shut down his transmitter after multiple requests by the FCC, insisting that he had a right to have a voice on the airwaves.
Some in the grassroots resorted to broadcasting without obtaining a license. The flashpoint of the grassroots radio movement was the court challenges made by Stephen Dunifer. Lower courts justified these unlicensed operations.
Suppliers
Antenna
An electromagnetic wave illuminates both an antenna and its feedline. Signal current induced on the outer surface of coaxial feedline may enter it at the antenna feedpoint. Common-mode signals induced on parallel transmission line may become differential at the receiver. Either makes the transmission line an unintended part of the antenna structure, which can degrade the directive pattern and forward gain. A current balun can attenuate unwanted coax shield current. A current or voltage balun can attenuate common-mode signals on parallel line. (consider using a Coiled-Coax Balun)
