Re: [amsat-bb] AO-27 (Yagi v. whip)

[Steve Bragg <steveb@xxxxxxxxxxxxxxxxxxxxx>]

JDWalkerJr@aol.com wrote:

> Has anyone compared the Arrow handheld yagi with a quarter wave whip.  I'm
> wondering if the performance difference is really significant.  I saw a
> demonstration of AO27 in Orlando last year and didn't observe the yagi did any
> better than my whip.  I've held off buying the antenna worried over whether it
> was worth the difference.

I think this can be explained in terms of the satellite's transponder. 
AO27 is an FM bird, which means its amplitude response is highly
nonlinear.  So, beyond a certain signal strength threshold, the noise
level isn't lowered significantly, even with much more power (or
equivalently, antenna gain).  So, in passes where these conditions are
met (specifically, a short range), it may seem that a Yagi is no better
than a whip.

On SSB or CW, the translators are linear, so you would really notice the
difference.

That's my shot at an explanation, anyway :-)

73,

Steve Bragg KA9MVA


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Steve Bragg KA9MVA
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