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Re: [TowerTalk] DRIVEN VERSUS PARASITIC 160 antenna

To:, K4PI <>
Subject: Re: [TowerTalk] DRIVEN VERSUS PARASITIC 160 antenna
From: Jim Lux <>
Date: Tue, 03 Jan 2006 11:50:09 -0800
List-post: <>
At 11:22 AM 1/3/2006, Tim Duffy K3LR wrote:
>Hi Mike!
>I think both systems would give you outstanding results!
>My current 160 antenna has lots of radials (120 per element (5) that are 1/4
>wavelength (137 feet) long = 75,000 feet of wire (radial wires intersect with
>buss wires and strap to conserve wire)). GROUND mounted radials under all
>elements are very important for this antenna to work. As mentioned in the 
>book, it has great F/B (32 dB at its peak) and has as much gain as a 
>full size 4 square array. It is easy to match and assemble, however the 
>F/B is limited to about 50 KHz (a good 4 square would have more F/B 
>The parasitic system requires less real estate than a 4 square.

An interesting tradeoff appears here.  Bandwidth vs directivity.  If you 
allow adjustable matching & phasing elements (or adjustable elements) you 
can get both really good F/B AND operating bandwidth.  It's the same as the 
"steppIR vs fixed beam" discussion.

There's a lot to be said for a system where it's install and forget.  You 
do all the hard work during install, and then, just sit back and 
operate.  Of course, a computer controlled system could do the same.

Jim, W6RMK 


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