[TowerTalk] Re: Why Rain static is worse on the top antenna. [was Quad vs SteppIR]

[david jordan]

Perhaps its something called gradient.  The closer to the clouds the 
more dense the charged particles (more noise)????

Guy Olinger, K2AV wrote:

>
> ----- Original Message ----- From: "david jordan" <wa3gin at erols.com>
>
>> Noise from point source such as a tower or building and percepitation 
>> static created when dropplets of rain or snow flakes that are charged 
>> come in contact with the elements of a bare wire or beam antenna.
>
>
> I would respectfully disagree.
>
> It is more likely that less charged raindrops come in contact with the 
> highly charged antenna or wire.
>
> A. It is well known that a substantial opposite charge on the ground 
> follows the charge in the clouds overhead.
>
> B. It is also well known that a capacitor consisting of two plates 
> will collect the highest density of charge on the surfaces of the two 
> plates facing one another.
>
> C. A yagi at the top of the tower will intercept a lot less than one 
> percent of the rain falling through it's turning radius.
>
> D. The yagi below it will get just as wet, since the yagi above is 
> about as effective a rain shield as an umbrella that's lost all its 
> fabric. Or stated another way, which one of you runs out to the tower 
> under the yagis to get out of the rain.
>
> Given C. and D., if the rain was charged and both yagis were neutral, 
> connected to ground, the lower yagi should be just as noisy as the 
> yagi above. But that can't be true, since the "shield effect" is well 
> documented.
>
> Try the charge on the ground, from A., and the rain quite less charged 
> (more neutral).
>
> Since the tower and the yagi's are connected to ground, the tower 
> complex assumes at least the ground charge. From B., the top yagi 
> functions like the surface of the capacitor plate, assuming nearly all 
> of the ground charge available to the tower, because it's closer to 
> the clouds.
>
> The neutral rain hits the high charge top yagi and the movement of the 
> charge making the drop equal to the yagi causes the noise.
>
> The neutral rain hitting the neutral lower yagi does nothing.
>
> Exaggerated, of course, but you get the point.
>
> The difficulty in seeing the ground/tower as highly charged, is that 
> the AREA or NEIGHBORHOOD is at an elevated charge underneath the 
> charged clouds overhead.
>
> In thinking about what might be noisy or quiet in a tower/antenna 
> complex, consider whether 1) there is some thing extensive and 
> grounded above it, or if to the side a bit, is there an upward moving 
> path from the TOP of something to something else substantial and 
> higher yet.
>
> 73, y'all
>
> Guy.
>
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