At 04:07 PM 10/12/02 -0400, Guy Olinger, K2AV wrote:
>There are many terrain configurations that would effectively nullify
>ground reflection at angles useful for DX, the bulk of reflection
>being too high a takeoff angle to be of much use.
>
>If one was in such a situation (taking away the ground reflection
>advantage) and the centers of the vertical dipoles were high enough to
>avoid heavy e-plane ground penetration loss, the two would play pretty
>much alike.
You are introducing another variable, and I don't think correctly. I just
re-read the ARRL Antenna Book's section on vertical and horizontal antennas
over real ground, as well as the section on the effects of irregular local
terrain in the far field. From what I can understand of the discussion, it
appears that, over real ground:
-- ground reflection gain basically benefits the horizontal but not the
vertical antenna.
-- ground losses in the far field affect vertically-polarized waves far
more than horizontally-polarized ones, particularly reducing low-angle
radiation.
-- refraction and diffraction due to irregular far-field terrain affect
both horizontally and vertically-polarized radiation.
Or to put it another way, the horizontal antenna starts out with an
advantage, pulls further ahead in the far field due to ground losses for
vertically-polarized radiation, and the effects of irregular far-field
terrain are basically the same for each.
Am I wrong? Any experts reading this discussion?
73, Pete N4ZR
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