[time-nuts] Difference in GPS antennas

[Robert Darlington]

Hrm, I'm looking for a sheet of Eccosorb to make an anechoic chamber (a very
small one) for testing 2.4GHz printed (PCB) antennas.  I'd be interested in
knowing the specs.   The idea with what I'm doing is that I can sweep the
antenna with the network analyzer and still be near the antenna to keep the
cables short, while at the same time not interfere with the measurements.  I
met a guy from Microchip last week that showed me what he was doing and what
works well for him.  He built a box about 8" high and about 5 inch square on
the bottom (inside dimensions).  Even though it's pretty parallel on the
inside, reflection is a minimum because of the material.

-Bob

On Fri, Aug 14, 2009 at 10:46 AM, Pete Lancashire
<pete at petelancashire.com>wrote:

> I have some (well a LOT) of microwave absorber. it looks
> like a mix of ferrite and rubber that has been bonded
> to a stainless steel cloth (think window screening) in the
> middle. About 1/8" thick.
>
> I can get the make, p/n and a picture this weekend if interested.
> I remember the company that made it got bought out, which then
> got bought out etc and I gave up.
>
> Price would be free+shipping, there are about 400 each
> sheets about 30x30 inches. Each sheet must weight 5 lbs.
>
>
> >
> >
> > On 8/14/09 9:13 AM, "Mark Sims" <holrum at hotmail.com> wrote:
> >
> >>
> >
> >>
> >> Some of the data collection runs that I want to do is with the patch
> >> mounted
> >> on a pizza pan and in a cake pan and see if that helps the performance
> >> by
> >> faking what a survey antenna does.
> >>
> >
> > If you can scrounge up some suitable RF absorbing material to put on the
> > pan, that might be an interesting experiment.  Maybe even something like
> > charcoal briquettes (I don't know if the resistivity is right..)
> >
> >
> >
> > I've tried the pizza pan thing, but that was because my antenna was a
> > magmount, and it was convenient. I didn't see if it gave better
> > performance.
> > A flat plate might actually be worse than putting the bare antenna up on
> a
> > pole, because it gives strong multipath from a very close reflection
> > point.
> >
> >
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