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[AMPS] Rain Static

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Subject: [AMPS] Rain Static
From: (Tom Rauch)
Date: Fri, 28 Sep 2001 10:27:30 -0400
> I'm listening on 20m at the moment and my antenna is a 3 element
> triband yagi at 50 ft. It has been raining for the greater part of the
> day and it's still raining now. The rain static has been driving me
> crazy.

Rain static, or what is called precipitation static, is almost always 
from corona discharge. This is the noise that sounds like a whining 
or musical hissing noise. It is generally NOT a charge "stored" in 
our antennas that we can "discharge" to earth because your 
antenna is at the potential of earth anyway. It is not noise from 
individual drops of charged water hitting the antenna.

There is another effect that is a slow popping noise that can be 
from the antenna charging, and then arcing. In that case, a leak 
resistor will help. Even hundreds of kilohms are enough. This is the 
only noise "grounded" elements or grounding reduces.

Most cases of corona noise are eliminated when the antenna is not 
the tallest structure around, or not "pointed at" a structure with 
corona. Structures without sharp points protruding into the air also 
reduce corona noise. That is what a quad antenna can do, and the 
corona reduction of the blunt sides is actually why the quad was 

>From that tiny bit of truth comes the exaggerated myth that quads 
or loops are always quieter than yagis or dipoles.


73, Tom W8JI 

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