[Top] [All Lists]

Re: [TowerTalk] optimum vertical length

To: <>
Subject: Re: [TowerTalk] optimum vertical length
From: "Paul Christensen" <>
Date: Mon, 1 Jun 2009 09:26:17 -0400
List-post: <">>
> The 43' vertical is much too tall to be usable on 15 and particularly
> 10 meters.

Seems to me the 43-foot verticals are reasonably good for operation between 
40M-20M where the lobes are contained to low angles and where the antenna 
can achieve good radiation efficiency without top-loading.

Back to the original topic as to the optimal vertical length...For base-fed 
verticals, my vote is for a radiator of 190-195 degrees where the zero 
degree elevation field strength is maximum, while minimizing high angle 
lobes.  Ideally, something like a SteppIR vertical would be used on all 
bands with a suitable motorized base matching network.  Of course, the 
reality is that such an antenna would be difficult to make for operation on 
160M, and even 80M.

If one could only find a 260-foot support to hang a vertical wire, then a 
motor could be used with a pulley system to optimize the vertical length to 
achieve the 195 degree radiator on all bands -- much like the SteppIR, but 
on a near half-wave scale for all bands.  An adjustable, motorized base 
network would be required to match the Hi-Z operating impedance of the near 
half-wave radiator for coaxial lines.  OTOH, if I had access to a 260-ft 
support, I would probably be using it for other antenna types as well.

Paul, W9AC



TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>