[TowerTalk] TowerTalk Digest, Vol 100, Issue 63

[Richard (Rick) Karlquist]

A half wave vertical or a vertical dipole doesn't work well when
elevated above ground because of reflection losses due to the
Brewster angle.  This problem is independent of any problems
with feeding it.  NEC may or may not model it correctly.

Rick N6RK

On 4/24/2011 7:52 PM, Jim Brown wrote:
> On 4/24/2011 4:21 PM, Rick Karlquist wrote:
>> It is difficult to feed a vertical dipole in the traditional
>> way in the center without the feedline affecting the pattern.
>
> Rudy Severns, N6LF, figured out a way to end feed it, and I expanded on
> it.  I built my version and hung it from a pulley high in a redwood,
> with the top about 110 ft above ground. It works, but when I compared it
> to my horizontal dipoles, the dipoles were ALWAYS a couple of S-units
> stronger. Before I built it and hung it in the tree I also modeled it in
> NEC.
>
> See my power point on Coax Chokes for photos and details of my feeding
> method and printouts of the modeling results. On the air comparisons
> correlate quite well with the model predictions.
>
> 73, Jim K9YC
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