[TowerTalk] Tower Height
Wed, 28 May 1997 07:36:44 -0700 (PDT)
I would think that if the real ground (when wet) was at, or very near
the physical surface of the ground, and if that was 60 ft. below the
antennas...your worst case....that you should STILL be able to work
Europe with no problem. 60 ft is plenty high for a yagi to work well
at reasonably low angles. I think there is another problem somewhere
else which explains the difference in your wet/dry performance.
73, DX de Pat, AA6EG/N6IJ...The contest station from the Government
On Tue, 27 May 1997, Roderick M. Fitz-Randolph wrote:
> There has been a recent thread regards putting a ground screen at the
> base of the tower and extending (purportedly) for a modest distance
> from the tower throughout a housing lot. There has been several statements
> regarding the effect on the take-off angle that the wire screen might or
> might not have. I would only like to add my personal experience in this
> regard without comment on the effect of the below-the-antenna ground system
> vs. the effect of distant reflection ground some thousands of feet or miles
> While living in Tucson in 1966 and 1967, I constructed a 3 el 20, 4 el 15 &
> 10 meter quad at 60 feet (Feb 1967 issue of QST). The most pronounced
> propagation phenomena I encountered was that when the soil was dry, I was
> able to hear and to work Europeans with some success...... but when it rained,
> I couldn't hear jack squat for 2-3 days afterward on any long haul DX. I
> attributed this (albeit it may be in error - if it is, please explain how)
> to the "virtual" rf ground being considerably below the literal ground when
> the soil was dry and therefore the take-off angle was considerably lower on
> transmit. The received rf angle appeared to have tracked with that as well.
> When it rained, the conductive nature of the soil was enhanced and made the
> antenna considerably closer to the ground and hence the take-off angle was
> sufficiently higher enough to rule out long haul dx.
> Don't know if it was far field reflection or the field close at hand that
> might have caused that effect. There can be no doubt, tho, as to whether
> it existed or not. I observed it many times. Any comments?
> Rod, W5HVV
> Remember! Unconstructive flames give me gas!
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