[Antennas] Charge build-up on antennas

Wed, 21 May 2003 21:59:24 -0700

My 90 foot vertical is able to drive a voltmeter
to 30V and the voltmeter's input impedance is
10 Meg, so the current is 3 uA.  Without the 
voltmeter loading the vertical, I could draw
1/2 inch sparks to ground.

Rick N6RK

> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Bob - AG5Q
> Sent: Wednesday, May 21, 2003 6:19 PM
> To: [email protected]
> Subject: [Antennas] Charge build-up on antennas
> 
> 
> During a rainstorm, how fast does charge build up on an antenna?
>  I suppose the area of the wires and tubing would affect this, as
> well as the amount of rain and wind. I'm wondering if a large 
> resistor across the antenna connector (say, 10K to 100K) would be able
> to discharge an antenna that is not connected to a rig or is a 
> much smaller resistance required (like a short circuit) to limit the
> voltage to no more than a few volts.
> 
> I'm assuming just an ordinary rain storm and neglecting the 
> effect of lightning in the area.
> Several years ago I noticed enough charge building up on a 20 
> meter dipole to jump across a small air gap of a ground switch that
> wasn't closed completely.  This occured during a light rain 
> storm.  However, I didn't take any quantitative data at the time.
> 
> There is a potential hazard to a rig if you connected an antenna 
> without shorting the connector terminals first, but would it  be
> enough to just put a resistor across the connector?
> 
> 73/ Bob - AG5Q
> 
> 
> 
> 
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