Antennas

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Antennas

Post by pawpawhunt on Sun Sep 29, 2013 9:55 am

Anybody make there own antennas for there receiver or transmitters. I built one for my low power tx with copper pipe and 4" plastic pipe 150 turns of wire and a veritable cap. Got a perfect match. Got about 3/4 mile range. Now I would like to make one for my low power FM trans. Any ideas?

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Re: Antennas

Post by 276merc on Sun Sep 29, 2013 11:34 am

FM is easier due to the VHF frequencies and lengths are much shorter.
For a 50-75 Ohm output transmitter a simple 1/4 wave groundplane is ideal. Dimensions for the vertical and radials are 31" for the low end, 28.5" for the middle, and 26" for the high end.

You can also use TV twinlead for a folded dipole and feedline and a 4:1 balun at the transmitter OR put the balun at the antenna and run coax. This is a fairly broadband antenna so 57" should be fine over the full band. The length includes the velocity factor of the twinlead.

Carl

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Re: Antennas

Post by N7ZAL on Sun Sep 29, 2013 11:35 am

Check the ARRL handbook or the ARRL Antenna book for many, many, options with construction techniques. If you don't need an omnidirectional antenna for FM you can use a multiple element "beam" type antenna and get a significant gain. If you are only needed a horizontal antenna a piece of 300 ohm twin lead will work nice....although horizontally polarized.
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Re: Antennas

Post by pawpawhunt on Sun Oct 06, 2013 5:33 am

thanks for the info. will be getting to work on it today!

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Re: Antennas

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