There are frequencies where there is a resonance with water molecules
which causes a quite high attenuation, even without rain or snow. I
can't find any data in a brief search, but recall that 54 GHz is one
of these. I did find some information which indicates that rain
attenuation is somewhat proportional to frequency squared.
73, Bob N7XY
On Oct 31, 2005, at 11:37 AM, Robert Chudek wrote:
> Hi Bill,
>
> The rain and snow attenuation seems to always raise this type of
> question. At the opposite end of the spectrum (440 MHz) where I ran
> ATV, snow and rain did not have a perceptible influence on the
> signals either. What did influence the path was foliage. In the
> winter we could shoot signals through the trees, but in the summer
> there was severe attenuation. I suspected the issue was the water
> or sap rising during the growing season.
>
> But that aside, is there a frequency where rain and snow have a
> significant attenuation due to its presence in the path?
>
> 73 de Bob - K0RC
>
>
> Message: 9
> Date: Mon, 31 Oct 2005 11:12:08 -0800 (GMT-08:00)
> From: Bill Jackson <k9rz@radiks.net>
> Subject: Re: [TowerTalk] Snow and rain attenuation
> To: Dan Hearn <dhearn@wwnw.net>, "Towertalk@Contesting.Com"
> <towertalk@contesting.com>
> Message-ID:
> <31955333.1130785928919.JavaMail.root@mswamui-
> backed.atl.sa.earthlink.net>
>
> Content-Type: text/plain; charset=us-ascii
>
> Dan,
>
> I work with 6 GHz point to point microwave systems at the
> railroad. We do not use heated antennas or radomes. However, I
> would recommend you install a dish antenna that includes a
> fiberglass radome. This will keep ice and snow from forming on the
> feedhorn and reflective surface of the dish and will actually lower
> the amount of wind loading from the antenna.
>
> At 6 GHz, the amount of additional path attenuation due to falling
> rain/snow in the air at 6 GHz is negligible and should not be a
> concern.
>
> 73 de Bill, K9RZ
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers",
> "Wireless Weather Stations", and lot's more. Call Toll Free,
> 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>
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>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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