[FOSS-GPS] Quadrifilar vs patch? Choke rings?

[Homan, Thomas]

Choke Ring antennas are best utilized in areas of high multipath (signal reflections.) The fins are precision tuned RF elements that, if damaged, can cause significant antenna performance degradations. 

For our applications (cm level land surveying) we utilize a choke ring only on fixed locations like CORS stations that are not likely to hit the ground or other objects. Field work relies on patch antennas that can take more abuse. Typically our base has a large ground plane and the rover has a smaller one.

As for your antenna WITH choke question, I don't have empirical evidence but would expect performance to be enhanced with both antennas but the relative difference to remain the same.

Tom

-----Original Message-----
From: foss-gps-bounces at lists.osgeo.org [mailto:foss-gps-bounces at lists.osgeo.org] On Behalf Of Danny Miller
Sent: Monday, June 20, 2011 10:59 PM
To: Open Source GPS-related discussion and support
Subject: [FOSS-GPS] Quadrifilar vs patch? Choke rings?

I have a pair of quad antennas, and a patch.

I don't have a choke ring for either one, although I'm considering 
building one, I don't have them now.  I have a CNC mill and it would be 
primarily an issue of getting aluminum billet stock.

Which is better for RTK?  I was just told that the quad without a choke 
ring may not be as good as a patch without the choke ring- in which case 
I can use a pair of patches.

WITH choke ring designs, are the patches or quad antennas better?

The rover may climb a 30 deg or so slope at times.  There will be some 
tilting of the antenna.

Thanks,
Danny
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