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

Danny Miller dannym at austin.rr.com
Tue Jun 21 14:01:39 EDT 2011


I understand the purpose of the choke ring in snubbing multipath.

Protection of a choke ring and/or quad antenna in a rover is not a major 
problem.  I can contain and protect it.  The rover has room for a choke 
ring.

My primary question is, if a choke ring is not used, is the quad or 
patch antenna better for RTK?  If a choke ring IS used, it is better to 
use with a quad or patch antenna with RTK?

I'm still not sure what that relative difference is, and which one comes 
out ahead for RTK.

Danny

On 6/21/2011 9:49 AM, Homan, Thomas wrote:
> 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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