I just sent away for a "Ramsey FM30" FM transmitter, build it yourself kit. It's only 25 mW and I want to maximize the power in one direction. Can anybody direct me to an antenna for sale or give me a link to a page to build my own. I would also appreciate any comments on this unit or tips on its construction. Should be here early next week. Thanks in advance.
Directional antenna for an FM TX ?
Jan 12, 2008
6 Replies
I dunno your local regs but often these sort of unlicensed FM transmitters are restricted to an ERP which won't cause problems to others. Upping the ERP by use of other than a simple aerial breaks this concession. If you need a greater range other frequencies are available for this.
*A fool and his money are soon partying *
Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
Maybe these guys have something that will work for you:
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An FM band Yagi antenna will provide you with the best directional characteristics. As noted above, the FCC (if you're in the US) might frown on you putting one of these on an unlicensed transmitter, but the legalities and consequences are for you to investigate. Directional FM antennae that you can buy:
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has the FM-6 FRINGE 6 ELEMENT 70"LONG $26.97
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Plans to build an FM Yagi are here:
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If none of those suit you, then you can do your own research on Google. Search for Yagi FM Antenna
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)
"In theory, there isn't any difference between theory and practice. In
practice, there is." - Yogi Berra
Hi Forrest.
You might be able to use a normal VHF Tv Antenna. The VHF TV band is just above the normal FM range (88-108 MHz), The TV antenna might have enough leighway in it's bandwidth range.
Just remember to remove any caps and coils that are in the TV antennas junction box, or you might mess up the tuning of the transmitter.
Reciprocity with antennas means that an Antenna will have the same gain whether it is transmitting or receiving a signal.
Peter
In the US its illegal to use an antenna other than the requied length of wire of a few inches.
greg
The O.P. should be aware of regulations in his country but mostly these specify EIRP for this class of device, and if it is a kit, then the builder may be as responsible for compliance as well as the maker. Using supplied parts is likely to maintain compliance but the builder is often able to make substitutions if he can verify compliance if challenged. Test and measurement is your friend.
Regards,
Michael
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