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Re: [TowerTalk] Matching a Delta Loop

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Matching a Delta Loop
From: K4SAV <RadioIR@charter.net>
Date: Thu, 19 Oct 2006 12:49:52 -0500
List-post: <mailto:towertalk@contesting.com>
The K8UR four square would give significant amount of additional gain 
below 35 degrees elevation. However it is significantly more complex 
than an inverted vee or a loop. It gives about the same gain as a four 
square on the ground but it doesn't require radials. The switching and 
phasing system is about the same complexity. Since it is a vertical 
phased array built around your tower, the resonant frequency of the 
tower becomes a player. Depending on the tower resonant frequency, you 
can get some performance improvement or you can completely destroy the 
pattern. If you start using the tower as one of the radiating elements, 
you will need radials on the tower. This might be a worthwhile project, 
but it will require a significant amount of effort.

..."For an equilateral, 1 lambda delta loop, you can find
a 50 ohm, vertically polarized, solution by feeding the
loop 1/3 up from one of the bottom corners."...

I can't get anything close to this.  For a delta loop with apex up and 
feedpoint at 33% from the bottom I get something close to 125 ohms.  For 
a delta loop with apex down, feeding it 33% from the bottom, I get close 
to 115 ohms. I can't find any place to feed an equilateral delta loop 
and get close to 50 ohms.

An inverted vee at the same height beats it.

Jerry, K4SAV

Jim Jarvis wrote:

>For an equilateral, 1 lambda delta loop, you can find
>a 50 ohm, vertically polarized, solution by feeding the
>loop 1/3 up from one of the bottom corners. 
>
>They work reasonably well.  I doubt they'll outperform
>the inverted vee @ 95' apex, however.  
>
>-0-
>I am still  trying to find something to out perform my 
>inverted v with the apex at 95 feet. Thank yall, 73, Joe N4JBK 
>-0-
>
>My recommendation, Joe, would be to try a K8UR array of 4 sloping
>dipoles from that 95' point, with the bottom halves coming back
>into the tower.  It'll give you some gain and directivity.  
>
>n2ea
>
>
>
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