> On Aug 22, 2007, at 11:22 AM, Dennis McAlpine wrote:
>
>> In this QTH, I currently have just a Butternut vertical mounted
>> five feet above ground. As soon as the snakes go to sleep for the
>> winter, I will raise it to 10' and do a better job with the
>> placement of the tuned radials.
>
de AA4LR ...
> Why do you want to raise the vertical? on 80m / 160m, the five feet
> likely won't make much difference. The key to verticals seems to be
> the radial field. If you can put down a bunch of ground-mounted
> radials, they should work better than a few elevated radials.
>
--------
For a multiband vertical you can do radials on the ground, which makes an
untuned counterpoise -- or you can use tuned radials, which have improved
performance when elevated.
For on-ground or buried radials, Bill is correct that a small increase in
elevation is immaterial, but only if the radial system is big enough.
Dennis' specific case of tuned radials would certainly benefit from higher
mounting. The benefit is greatest on the high bands where the distance in
wavelength above ground is greater. For the low bands, 10 ft. may not make
much difference. Raising the antenna also gets it above the objects that
clutter the area near ground -- these can add loss or alter the radiation
pattern of a low antenna.
I have not had experience with multiband verticals, but in the past I have
used elevated ground planes for 15, 20, 30 and 40 meters -- all of which
performed much better than their ground-mounted equivalents.
73, Gary
K9AY
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