Topband: Covered /bare antennn wire

[Tom W8JI]

> It also doesn't seem to matter if the antennas in the stack have their
> elements insulated from the boom or bonded to it, the top antenna always 
> has
> +20 dB or more noise.
>
> 73 John N5CQ


That agrees with dozens of other reliable A-B reports by other people. 
Everyone who has side-by-side compared, or only changed if the elements are 
insulated or grounded and nothing else, reports the same.

It also agrees with common sense.

The noise is caused by the voltage gradient ***between*** the element (or 
wire) and the air and what is in the air around the element. It's quite 
obvious we would want the element to approach the potential of the 
surrounding air to reduce noise, but the impedance of the air around the 
element is so high and the voltage is so high insulation (which is generally 
wet anyway during bad weather) does not make any significant difference.

People tend to think backwards. They think the element charges and that 
charge makes noise. What really happens is the element or object is at earth 
potential, and the sky and air around the object is at another grossly 
different potential.

The only noise caused by an element charging is a "pop" or arc as the 
element moves closer to air potential, until the voltage is high enough to 
break down some insulation path to earth. This is a huge problem with T 
network antenna tuners that feed big antennas without a ground leak path. 
The antenna trickle charges the output capacitor (with microamperes of 
current) until the cap flashes over. This sudden rings the tank with high 
voltage, and that blows the diodes in the directional coupler detector.

We certainly do not want things to charge to the point something flashes 
over and is damaged, but a ground leak does not reduce p-static (corona) 
noise. A ground leak does not reduce the chance of a lightning strike, 
either. Neither do those tower whiskers (NASA has extensively tested that).

73 Tom