Dan Evans wrote:
> With antennas that low, I think the biggest influence is the vehicle and
> not the take off angle. It may be completely wrong, but I always
> pictured it as the vehicle in the near field coupling with the antenna,
> and creating considerable loss.
>
> At some "minimum" point above the vehicle, this loss is reduced to
> negligible level. From Jon's, W0ZQ /R, data, it would seem that height
> for 6 meters would be around 21 feet. Actual numbers would depend on
> the band involved, and the antenna.
>
> All of this is my opinion based on my experience and anecdotal
> evidence. I'm a Rover, not a scientist:-) Your points per mile may vary!
>
> 73
> Dan
I've had a somewhat similar problem with the vehicle being in the field
of the 6M ant. When I first started roving, I mounted the 6M beam at
the bottom of my "stack". This put it at only 10 ft above ground and
about four feet above the vehicle.
I experienced a weird bunch of Rf feedback/SWR problems. Finally traced
it to the short distance between the 6M beam and the vehicle. With the
beam pointed over the Jeep, the SWR would go above 2:1 and I experienced
RF feedback.
Now I mount the 6M ant on top of the stack. It still only at 15 ft and
I can see some interaction when I turn over the vehicle but it's minimal.
73,
Tom K6EU/r
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