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Old June 17th 06, 05:35 AM posted to rec.radio.amateur.antenna
Roy Lewallen
 
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Default Force 12 C-3 on 6 Mtrs

Tom Ring wrote:
Tom Ring wrote:

The only way triple f yagis work well is if the elements are swept
forward. That pushes the right and left lobes from the straight
elements into the center.


Well known in the VHF and UHF design world, probably almost unknown here.


That's too bad, since I've described that technique on this group a
number of times in various contexts. It allows you to make a very nice
40/15 meter antenna, for example. Bending the wires of a 40 meter dipole
in 30 degrees aligns the lobes on 15 meters, but doesn't alter the 40
meter pattern much. And of course it's widely used for TV antennas,
where the upper VHF bands are about three times the frequency of the
lower ones.

This doesn't make an extended double zepp as posted earlier. An EDZ is
5/4 wavelength, which has a single lobe in each direction broadside to
the antenna when the antenna is straight. A dipole operated at three
times its lowest resonant frequency is about 3/2 wavelength, and has
four lobes in a cloverleaf pattern, rather than two in opposite
directions like an EDZ. So it requires bending if you want just two
major lobes in opposite directions.

Roy Lewallen, W7EL