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Old October 2nd 03, 03:52 PM
Cecil Moore
 
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Reg Edwards wrote:

W5DXP wrote:
But don't allow the vertical radiator to be longer than 5/8WL
on the highest frequency of interest.


Cecil, The difference between 3/4-wave and 5/8ths wave insofar as low and
medium-angle stuff is concerned is not worth thinking about. It is
unnoticeable in normal use. You ought NOT to go around unnecessarily
frightening people into hacking the tops off perfectly good antennas.


I wasn't thinking about a 3/4-wave, Reg. I was thinking more about two or
three wavelengths long where most of the radiation is high angle when low
angle is what one needs on the higher frequencies. You said to make the
vertical "as high as you can manage". So don't make it longer than 3/4WL.

However, a 3/4WL vertical has its maximum gain at a take-off angle of
46 degrees. A 5/8WL vertical has its maximum gain at a take-off angle
of 16 degrees. At 16 degrees, the 5/8WL vertical has about 3dB gain
over a 3/4WL vertical.
--
73, Cecil http://www.qsl.net/w5dxp



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