[time-nuts] Choke Ring Design for L1

[WarrenS]

What I have found is if you have a decent view of the sky or even when 
indoors on an upper shelf,
by turning the pie pan lip up, it helps the antenna location placement 
sensitivity issue.
I'll leave it to the antenna Experts speculate on why that is.

ws

***************
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
>