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Re: [TowerTalk] book Tribander comparison test

Subject: Re: [TowerTalk] book Tribander comparison test
From: jimlux <>
Date: Tue, 01 Mar 2011 22:26:07 -0800
List-post: <">>
On 3/1/11 5:24 PM, Jim Brown wrote:
> On 3/1/2011 5:04 PM, Barry Kirkwood wrote:
>> Are you telling us that yagi element spacing has no effect on front to back
>> ratio?
> I don't think anyone has implied that.

However, it's pretty close.. given total freedom to pick lengths, and a 
single frequency, there's an amazingly wide range of spacings for the 
elements that works pretty well. (for 3 element systems with the middle 
element driven)

The trap for the unwary (esp with a SteppIR) is that in some 
configurations, the "tuning" is very sensitive, and small changes in the 
lengths or relative orientation will change the F/B pretty noticeably. 
Won't change the gain much or the match, but to turn a 20dB null into a 
10dB null is awfully easy..

If the antenna is in the wind, and the elements are moving around, 
that's where that narrow sensitivity bites you.


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