[time-nuts] Important parameters for a GPS/GNSS antenna

Magnus Danielson magnus at rubidium.dyndns.org
Sat May 2 12:36:30 EDT 2015


Attila,

On 04/29/2015 10:43 PM, Attila Kinali wrote:
> Moin,
>
> I recently discovered openEMS[1], which is, very simply put, a fancy
> antenna simulator. I played a little with it and thought about
> trying to optimize an GPS patch antenna design for timing use.

Will take it for a test-drive to see how it align up to NEC2 and variants.

> But I had to discover that I actually do not know what to optimze for.
> There are many paramters I can think of (RHCP/LHCP, symmetry of
> gain, feedpoint impedance vs frequency, stability of phase centre,....)
> which all seem to be to some extend important, but which ones do actually
> matter for the timing reference performance?
>
> My google skills failed to locate any relevant documents on this topic.
>
> Could someone be so kind and give me some pointers, what to search
> for, documents or the like?

The thing that we care about is:

1) LHCP surpression
2) Directivity/ surpression of signals below say 5 degrees above horizon
3) Phase stability with regard to azimuth/elevation
4) Relatively flat gain above 5 degrees

Do read up on the Novatel pinwheels, as they illustrate the various 
concerns and how they do that in a new fashion.

Cheers,
Magnus


More information about the time-nuts mailing list