View Full Version : mobile fm broadcast antenna
07-25-2002, 04:30 PM
someone posted this:For best performance, the antenna should be on the outside of the car, a good place would be the roof. You might be able to use a CB magmount antenna. Just remove any base loading coils and trim the element for the middle of the FM band.
could someone please give more detail about doing this?
07-26-2002, 02:21 PM
A mobile antenna would be quite feasible for operation in the FM broadcast band.
Probably the best antenna for starters would be a 1/4 wave design, using the roof of the vehicle for a ground plane. Yes, if you use a CB antenna, you would have to eliminate the loading coil.
To calculate the length for the whip, simply use the following formula:
234/freq.in MHz X 12=length of mast(in inches) The length for mid-band would be approximately 28.6". If you can find a ham operator with an MFJ antenna/swr analyzer, it can make the job much easier
At resonance, this antenna should present close to a 50 ohm match.
Good luck and let us know how your mobile operation turns out!
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