Home › Forums › temp › The Facts about the EDM electronics FM Transmitter › Re: FM milliwatts and compliance
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The rules specify a maximum field strength at at given distance. As mentioned in this thread, most, if not all of us, lack the equipment to assure compliance by direct measurement. The easiest way to control the field strength from a low power FM transmitter is to trim the antenna to achieve a certain range. The FCC states in a fact sheet, and not in the rules, that the expected range of a compliant transmitter with regard to field strength is 200 feet. If you are concerned about compliance then it appears that if you trim the antenna to get this range then you will be close to the limits of the rules.
As a point of reference, I have a 200 foot range (using a car radio) from my Ramsey FM-25A with the antenna extended 4 inches.
250 uV/M as measured from a distance of 3 meters.