FM Transmitting Antennas

If you're using a low-power FM transmitter, you're going to need a good antenna so that your station's signal is clean and clear. It doesn't take much to transmit a nice signal a block or two and really, that's about all the distance the FCC allows for a low-power, unlicensed transmitter. While you may think that more power is better, consider that radio waves can cause interference with other devices within your transmitter's coverage area, which is not only illegal, it could conceivably bring the FCC to your doorstep for an extremely healthy fine ($50,000 or more). So resist the urge to purchase that 5 or 10-watt unit and choose one in the 10-100mw (milliwatt) range instead. A block or two of range is really all you need -- outside of that, nobody would be able to see your light show anyway.

Any transmitter needs an antenna of some kind, and some DIY'ers have found that a simple 3-5' wire connected to the transmitter's antenna output works adequately. But without getting into the seriously deep physics involved, suffice to say that the best success is had with antennas that are "matched" to the transmitter's electronics and transmitting frequency. Often, a transmitter will come with what's supposed to be a good match, but that's not always the case. You can, however, build your own very high-performance dipole antenna, and the directions for doing that are included below. The build is an easy one and should take only an hour or two using easy-to-find parts at your local home improvement center.

 

* How to Make a Dipole Antenna - an easy DIY project for an inexpensive yet high-performance antenna

IMPORTANT - with most any transmitter, NEVER power up the transmitter without an antenna! This can permanently damage the transmitter's output electronics because without an antenna, there's no place for the "power" to go. Likewise and for the same reason, never 'short-out' the antenna connection, either.