Now that you have been inspired to set up a micropower broadcast station, this addendum will provide you with further details to assist your endeavors.
One of the first questions commonly asked is “How far will the signal go for a given power level?”. Unfortunately there is not an exact answer to this question. It is a function of antenna height, power level and local topography. Obviously, 40 watts with a antenna height of 50-60 feet is going to go much further in Kansas than in Manhattan. The following chart assumes relatively flat terrain, low rise buildings and an antenna height in the range of 50-70 feet.
Power level Maximum distance
1 watt 2-3 miles
10 watts 4-5 miles
50 watts 8-10 miles
100 watts 10-14 miles
Another question is, “How do I choose a frequency”. The FM broadcast band is broken up into channels which take up a certain amount of spectrum space. You need to choose a frequency that does not have an intelligible signal on that channel nor one on either side of it within the area you wish to cover. For example, if you found that 101.5 was clear, then 101.3 and 101.7 must be clear as well. In urban areas it may be hard to meet these conditions but do the best you can. Driving around in a car with a digitally tuned radio is a good way to survey an area for an open spot.
Cost of setting up a station is always a concern. Depending on whether you build your own transmitter from a kit or purchase one already assembled and the type of audio equipment you choose, the cost can range from $500-$1500. Free Radio Berkeley, the publisher of this book, provides a full range of transmitter kits, antennas, cabling, audio equipment and complete plug and play station packages. Other vendors of equipment can easily be found by searching the internet.
In addition, Free Radio Berkeley offers 4 day radio camps on a regular basis. During the 4 day period you will actually build an FM broadcast transmitter and learn how to set up a broadcast station. These camps are held at Free Radio Berkeley’s facility in Oakland, California. Camps can be scheduled at other locations, both inside and outside the US, by prior arrangement. A volunteer/apprentice program is offered to anyone who wishes to take several weeks or longer to work and learn at the Oakland facility. For full technical detail go to the FRB web site (www.freeradio.org) and download the Micrpower Broadcasting Primer.
Contact Free Radio Berkeley for additional information.