Fw: Re: Topband: Lightning Protection

[Tom Rauch]

> carbonized thread types were known as "static wicks".  They were
> attached to the training edges of the wings and tail to discharge any
> corona buildup on the aircraft as it flew through rain or snow. 

The key difference between using them in the intended application 
and the new application on towers and building is the size and 
capacitance of what you are trying to discharge.

On aircraft, they only have to bleed off a well-insulated small object 
with very little charge storage...the airplane.

When you place them on the earth, or an object connected to the 
earth, they have to discharge the earth.

That is unlikely to happen in our lifetimes, because the earth is a 
huge reservoir of charges. 

> Presumably the static would discharge off of the static wicks rther
> than off of the radio antennas, thereby reducing the precipitation
> static noise in the radios.

That would work if the tower did not re-radiate the "noise" as the 
corona flew off the discharges, and if the antennas were lower than 
that corona stream or in it.

The whole problem centers around voltage gradient between our 
antennas and the charge up in the sky. We have to somehow 
reduce that gradient. One way is to lower the antenna, another is 
to make it "blunt", another is to put something grounded above our 
antenna and some distance away so it is the highest object and far 
enough away we don't hear noise.

We had a repeater on top of a tall building that was fine, until they 
installed "wicks" and one wound up near the antenna. Then we had 
corona noise during every storm. We had to move the antenna far 
away from the wicks and the nasty corona noise they made.

My Beverages pointed back towards my tall towers "hear" corona 
noise quite well during storms, so I suspect you'd need quite a bit 
of spacing on 160 meters.
73, Tom W8JI
W8JI@contesting.com