On 9/7/2011 10:01 PM, Jeff Liebermann wrote:
On Wed, 07 Sep 2011 10:48:55 -0700, Jim
wrote:

Actually, humidity doesn't affect the charging all that much. What
humidity affects is the leakage current across dirty insulators.
P-static is a nice example of static charging in rain at 100% humidity,
for instance.

It's true that dry dust or blowing snow are more notorious for charging,
but just the clear sky current could provide some charging.

Well, what I've noticed is that when the humidity is low, I throw
lightning bolts when I walk across the carpet or slide across the car
seat. When the humidity is higher, then I don't have those problems.
I don't know how this correlates to charge buildup on an antenna, but
my guess(tm) is that there would be some connection.


It has to do with the leakage currents discharging you when it's more
humid. Interestingly, humid air has a higher breakdown field than dry air.



In a past life, I helped design a marine HF xceiver, which had a +7dBm
mixer (SBL-1) in the front end. Between the antenna and the mixer,
was a low pass filter with no capacitors to ground. There were a few
failures, most of which were due to nearby lightning hits. However
some of these failures were blamed on static buildup.

And, you can take ESD hits that degrade, but don't destroy, the part.
I've got some LNAs in my desk drawer that appear to work just fine,
except the NF is a bit higher than it used to be.