[time-nuts] GPS antenna in snowy environment (was: LEA-6T Software.)

[Joseph Gwinn]

On Thu, 28 Aug 2014 09:15:18 -0400, time-nuts-request at febo.com wrote:
> 
> Message: 5
> Date: Thu, 28 Aug 2014 15:04:36 +0200
> From: Attila Kinali <attila at kinali.ch>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: [time-nuts] GPS antenna in snowy environment (was: LEA-6T
> 	Software.)
> Message-ID: <20140828150436.2cbdd2a08a5d7099849123a7 at kinali.ch>
> Content-Type: text/plain; charset=UTF-8
> 
> On Mon, 25 Aug 2014 10:48:51 -0400
> Dan Kemppainen <dan at irtelemetrics.com> wrote:
> 
>> Also, I have a low cost antenna coming. It's one of the Synergy systems
>> puck type amplified antennas. I remember some time back a bit of chatter
>> about improving GPS antennas for timing, by providing some sort of guard
>> ring or choke to prevent low angle reception. Are there any good links
>> anyone could provide on what may be worth building or playing with. Keep
>> in mind, I live in snow country (~300 inches/year) so a something that
>> gathers a lot of snow could be undesirable! :)
> 
> How much snow you get is mostly irrelevant. It's more important 
> how much accumulates ;-)
> 
> A cone hat over your antenna should solve quite a bit of the issue.
> The problem is, that you need quite a steep cone or you need to heat
> it constantly above 0°C, as snow tends to stick to everything, even
> smooth walls.
> Maybe also worth a try would be to grease the cone. But i've only heard
> of that and never seen it in action. So i cannot tell whether that helps
> in any way.

I had to study this issue once.  The question was if we needed to 
provide antenna heaters in the far North.  Like Minnesota and Alaska.

Turns out that snow and ice are almost transparent to 1.5 GHz, while a 
fat seagull perching on the antenna was a problem, so we did the tall 
cone and let it go at that.

The only exception to the transparency is salty sea ice, which can 
accumulate on shipboard equipment.

Joe Gwinn