[TowerTalk] Quad elements no rain static.

[Grant Saviers]

I agree with K1TTT's analysis.  Another factor contributing to which 
antennas are noisy is how the stack is arranged.  If it is the classic 
"Christmas Tree" layout with smallest yagi on top then that provides 
limited "shielding" of the voltage gradient to the lower antennas.  My 
stack has 80m 100' long elements on top and all below it are quiet.

I think geometry differences and/or a difference in the site matter. 
Yagis have lots of discharge points, ie sharp edges.  Quads usually 
don't and the feedpoints aren't at the top and wire insulation may make 
a difference. Also, note one recent TT post reporting that a ground wire 
around the rotator bearings tamed the noise.  A ball bearing oil film 
has a breakdown voltage around a few dozen volts, in my experience.  So 
if there is arcing across the oil film the entire mast and assembly is 
bouncing around in voltage.

IMO it doesn't matter if the driven elements are grounded.  A current in 
any yagi element discharging voltage from its tip is going to introduce 
noise into the driven element.  The corona itself is a broadband white 
noise source so can be picked up by other antennas.  But the fact that 
lower ones can be quiet tends to reinforce the idea that the current in 
the discharging elements is the larger contributor.

Regarding charge accumulation from water and snow landing on the 
antenna, there is a lot to learn from the aviation world. However, 
aircraft are certainly contacting enormously more charged particles than 
precipitation landing on an yagi.  What is interesting are the devices 
added to aircraft to dissipate the charge and eliminate radio interference.

https://en.wikipedia.org/wiki/Static_discharger
https://www.aviationpros.com/article/10386443/precipitation-static-combating-noise-and-other-effects
https://apps.dtic.mil/dtic/tr/fulltext/u2/261029.pdf

Next time I have noise, I will check my top 4L SteppIR for its noise 
level.  It's on a tower separated from the stack.  If the logic re quads 
is correct then a SteppIR being fully insulated should be quiet.

Grant KZ1W


On 12/5/2018 2:48 AM, Máximo EA1DDO_HK1H wrote:
> It is an interesting thing, because many Yagi have the dipole at DC ground, at the center support, part of the gamma-match system.
> I wonder if these Yagi suffer same rain noise.
> By the way, not every Quad uses Gamma feed. Most are balun and coax feed.
> 
> 73, Maximo
> 
> 
> ________________________________
> De: TowerTalk <towertalk-bounces at contesting.com> en nombre de Alton McConnell <amcconnell3 at hotmail.com>
> Enviado: miércoles, 5 de diciembre de 2018 10:26
> Para: TowerTalk at contesting.com
> Asunto: [TowerTalk] Quad elements no rain static.
> 
> 
> I believe the reason why quads do not  exhibit rain or snow static is because the driven element is at DC ground.
> 
> I feed mine with a tri gamma match
> 
> Sent from Samsung tablet
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>