[time-nuts] Choke Ring Design for L1

[Robert Berg]

Does someone know which commercial antennas are 3D designs? Sounds like 
the $200 AeroAntenna version mentioned previously might be a 3d design, 
although it's a little tough to guess by simply looking at the enclosure 
and a single drawing. An evaluation of some 3D antennas: 
http://www.novatel.com/Documents/Papers/3D_choke_ring.pdf

Bob

Bob Camp wrote:
> Hi
>
> That's one of the many things that makes this all a bit tough to work out. 
>
> Even without a choke ring, a pie plate, or a ground sheet involved you can move a cheap GPS timing antenna 5 feet and see a very real change in plots. Up / down / left / right often the move does not make much sense. I suspect that if the antenna was 500 feet above all local obstructions that would not be true. In more typical "home user" settings it certainly can be. 
>
> Plotting software has been around for a *long* time......
>
> Bob
>
>
> On Mar 14, 2010, at 5:59 AM, Peter Vince wrote:
>
>   
>> As I understand it, the GPS signals are circularly polarised, and so
>> surely reflections will reverse the sense of that polarisation such
>> that the antenna will be insensitive to them?  Maybe Warren's simple
>> pie dish is working by shielding the antenna from the true MULTI-path
>> reflections, and any direct SINGLE reflections it produces are ignored
>> due to the polarisation reversal?
>>
>>     Peter
>>
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>
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