[time-nuts] Choke Ring Design for L1

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Mar 14 11:39:48 UTC 2010


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
>
>    
But the incident wave is diffracted at the edge of a finite ground plane 
creating a surface wave that the patch antenna element does respond to.
Unless one has a microwave anechoic chamber one has to calculate the 
antenna response with an EM simulation program.
Its not possible to infer an antenna's response to multipath by merely 
measuring its apparent response pattern to a GPS SV except perhaps when 
one has a detailed and accurate EM model of the antenna environment.

Bruce




More information about the time-nuts mailing list