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Angle of radiation
On Wed, 13 Dec 2006 07:54:54 -0500, chuck wrote:
I was thinking this particular antenna would have a lower radiation angle The quarter-wave ground-plane antenna's vertical radiation pattern approaches that of a half-wave vertical as the radial droop approaches 90 degrees, while the feedpoint height remains fixed. Whether one views that as significant is subjective, of course. Hi Chuck, Lifting a ground plane off the ground, so that drooping the radials could, in fact, be drooped; this does more to raise the gain, than drooping the radials (something like four-fold more). Already having the antenna off the ground, and then drooping the radials does accomplish a lowering of the angle, and increasing the gain. However, I would propose drooping is largely practiced more to pull the match into 50 Ohms from 35 Ohms than for any perceived benefit in "Gain" (which is perhaps all of half a dB or slightly more). Changing the height could easily erode that partial dB. Moral: Droop the radials for match; Raise (correctly place) the antenna for gain. 73's Richard Clark, KB7QHC |
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