[TowerTalk] Gap Vertical, Verticals

[Steve Weisbrod]

Cushcraft recommends for their R7000 8ft min but reports that going above   
17ft is of no real value.

73 Steve W8GAZ

 ----------
From:  'force12@interserv.com'
Sent:  Monday, August 04, 1997 8:55 AM
To:  steve; Jon E Hamlet; 'towertalk@contesting.com'
Cc:  'towertalk@contesting.com'; 'n3hrt@eagle1.eaglenet.com'
Subject:  Re: [TowerTalk] Gap Vertical, Verticals

Original Subject:
Re: [TowerTalk] Gap Vertical, Verticals in general

Good morning.

I have always been fascinated by various verticals appearing to "work"
better when they are elevated. If it is really an HF vertical-vertical,   
then
the highest one would want the feedpoint is about 1/4 wavelength high,   
such
as a vertical dipole. As it moves higher, there is a high angle lobe that   

appears and overtakes the energy on the lower lobe. The lower lobe is
eventually recovered, but not until the antenna is substantially higher.

Does anyone else model these things?? All of our software indicates this   
to
be the case. Our ZR verticals are vertical dipoles and really do not want   
to
be mounted very high. Since they are for 20-15-10, elevating it too much
will create the high angle lobe on 10 mtrs, although 20 might be all   
right.
As a 1/4 wave vertical is elevated to where the feedpoint matches the
vertical dipole, the pattern looks like the vertical dipole! This means   
the
main lobe is compressed from the typical 1/4 wave vertical pattern at a
lower height.

If a vertical indeed works better at a high height, there might well be
something else going on.

What does anyone else's models/experience show?

Many are tower mounted, so it might be interesting.



Have a good day and 73,
   Tom, N6BT
   Force 12 Antennas and Systems
   (Home Page   http://www.QTH.com/force12 )



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