[TowerTalk] Quad vs SteppIR
Tom Rauch
w8ji at contesting.com
Mon Aug 30 11:57:13 EDT 2004
>
> When I had a quad and monobanders, the quad was always
quieter from snow
> static than the monobanders. Was wondering if the SteppIR
would be quieter
> than a regualr aluminum beam during a snow storm since the
snow would be in
> contact with fiberglass instead of aluminum? Or would the
static charge be
> the same regardless of material?
There is some dispute about what causes snow static and such
Tony.
The two schools of thought are the noise comes from charges
migrating from charged particles like snow flakes, dust, or
rain drops hitting the antenna, or corona discharge.
My own belief is it is corona discharge, based on
observations of different antennas here and at my other
locations over the years. My reasons for believing it is
corona related are:
1.) Lower antennas are hit by the same junk, but are much
quieter.
2.) I tried to charge droplets with an electrostatic paint
sprayer and could not make noise, unless I made corona.
3.) Beverages that are insulated wire pick up just as much
noise as bare wire antennas, and the ONLT Beverages that
hear the noise are the ones that point at my tall towers.
Same for small receiving verticals in directive arrays, they
clearly indicate the noise is from the direction of my tall
towers. Noise would NOT have a direction of arrival if from
within the antenna.
4.) Lower yagis show increased noise when pointed at tall
towers. Again they are all being hit by the same stuff, but
the noise is very clearly strongest when I point an antenna
at a much taller structure.
5.) When I had problems with two-way radio noise on tall
buildings, it was cured only by adding a taller pole on the
building some distance away from the antenna.
I'm sure others will disagree with this, but I've seen the
things outline in 1-5 repeat many many times, and I've never
observed anything to the contrary. My opinion is while I
can't say every case is corona, everything I've seen (and
I've looked carefully) is a clear indication it is.
With that in mind, any antenna with sharp points out in the
air would be more susceptible than a quad that has long
fiberglass supports and blunt wire sides exposed to the
high field gradient.
I'd suspect the fiberglass housing over the SteppIR's
element would help reduce corona noise, assuming the tower
had no other sharp pointed objects sticking out. Whether it
would be better than a quad for P-static, I have no idea.
73 Tom
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