[time-nuts] Poor man's choke ring

Robert Atkinson robert8rpi at yahoo.co.uk
Thu Mar 25 07:56:50 UTC 2010


You beat me to it Bruce!
They call it a Stealth(tm) Ground Plane. It's used in the Zephyr Geodetic 2 antenna.
See http://www.trimble.com/infrastructure/pdf/gnss-choke-ring-antenna_brochure.pdf
"proper" attenator materials (Eccosorb by Emerson & Cuming and I think Grace make some) are expensive, but I've had some luck with carbon loaded anti-static foam in the past. I've used it to kill enclosure resonaces for EMC and at around 4GHz to reduce skin leakage and ground reflections when testing aircraft radio altimeters on the ground.   
 
Robert G8RPI

--- On Thu, 25/3/10, Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:


From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
Subject: Re: [time-nuts] Poor man's choke ring
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Thursday, 25 March, 2010, 1:18


Neville Michie wrote:
> If I understand the choke ring antenna it is to remove signals propagating across the ground plane.
> Now if there was a very lossy layer on the ground plane any signals propagating across it would be attenuated.
> For instance, if you find a plastic that melts in your microwave, a sheet of that plastic over your ground plane should work.
> Or do plastics that attenuate enough not exist?
> 
> cheers, Neville Michie
> 
Trimble produce an antenna with a dissipative ground plane.

Bruce


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



      


More information about the time-nuts mailing list