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Old 04-16-2014, 04:34 PM
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cbenham cbenham is offline
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Join Date: May 2006
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Quote:
Originally Posted by old_tv_nut View Post
See the section on "feeding a dipole antenna"
http://en.wikipedia.org/wiki/Dipole_antenna

I presume your matching transformer is 75 ohms (your coax side) to 300 ohms (your dipole side)? According to the above you should not be using a 75 to 300 ohm matching transformer unless you use a folded dipole.
I built a 75 ohm FM antenna out of 75 ohm coax just as given in the first figure of the wiki attachment. I did include a triple loop right at the antenna to provide some isolation between my flea power transmitter and the antenna.
It's a pretty efficient antenna, scared me when I drove around the neighborhood and could pick it up almost a mile away! I lowered the output power with a 10dB coax pad. Attached is a picture.
Attached Images
File Type: jpg FM ANTENNA 60.75 inch 75 Ohm FM Dipole .JPG (36.9 KB, 9 views)
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