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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