I can tell you that for my station here in Seattle, I notice significantly
improved radiation when we get heavy snow, mainly because it is such a pain
to drive so I just end up staying home and operating more.... for that
reason, I love the snow...
[mailto:firstname.lastname@example.org] On Behalf Of Martin AA6E
Sent: Sunday, January 14, 2007 6:13 AM
Subject: Re: [TowerTalk] Effective of ground snow on Antenna
There is snow and there is snow. (Ask a cross country skier.) Dry powder
has lots of air in it, which gets partly compacted out after a while.
Wet snow has liquid water mixed in, etc.
There are two effects to worry about. The biggest problem would be RF
absorption (loss), which would be worse for higher liquid water content
IMO. The other issue is dielectric constant. Ice and water have high
"epsilon" - which means that your antenna will be detuned. (Apparently
not an issue if your SWR is OK.) It also means that you would get some
change in antenna patterns because you have a layer of (somewhat) lossy
dielectric (snow) over your normal ground. Ground is still ground, but
the snow will dissipate some of your power, and your antenna pattern
will change somewhat. It could be modeled, if you know the properties
of your snow.
73 Martin AA6E
Ken Kinyon wrote:
> Is anyone aware of any studies done on the effect of ground snow on the RF
> reflectivity of the soil underneath the snow?
> It is not usual for the front range of Colorado to have significant snow
> ground for any significant length of time.
> However since two feet of snow fell shortly before Christmas, We have had
> least another foot and most of it is still here although compacted
> significantly. It is my subjective observation that I an not receiving or
> transmitting as well since the snow fell. Everything looks normal with
> equipment. Antenna SWR and directivity seem unchanged. Is it possible
> snow is absorbing RF that would ordinarily reflect off the ground and
> with direct radiation, thereby changing the vertical radiation pattern?
> idea is that the snow is reflecting RF, raising the effective height of
> ground (which I assume is some feet under the actual ground normally),
> making my antenna perform as though it were closer to ground.
> Yes, cabin fever makes one ponder strange things. ;<)
> Thanks and 73,
> Ken W7TS
> Kenneth E. Kinyon
> 34 Princeton Circle
> Longmont, CO 80503-2106
> E-mail: W7TS@comcast.net
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