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[DPRG] GPS and ground planes
Subject: [DPRG] GPS and ground planes
From: Jeff Sampson
jsampson at pobox.com
Date: Sun May 4 15:32:50 CDT 2008
Kipton Moravec wrote:
> On Sun, 2008-05-04 at 00:11 -0500, Jeff Sampson wrote:
>
>>Hi,
>>
>>I played with my GPS. It is a Rikaline USB GPS module for a laptop
>>computer and has the Sirf II receiver. I noticed the resulting path that
>>I recorded didn't look like I expected. It was close, but looked sloppy.
>>So I stuck it to a piece of steel sheet, about 8"x9" and ran it again.
>>(This is one of those that has a magnet to stick to the top of your
>>car.) It worked much better the second time.
>>
>>Does a GPS receiver prefer a ground plane? Or did I just have a better
>>fix the second time? If a ground plane is preferred, does anybody know
>>the recommended size of the plane?
>
>
> Yes. Here is a data sheet on patch antennas.
>
> http://www.specemc.com/docs/antenna_catalog.pdf
>
> It gives curves for ground plane under a patch antenna.
>
> I am using 40 mm x 40 mm under a 12.5 mm x 12.5 mm antenna.
Thanks Kip, this has lots of good information. It looks like it still
not an exact science nad has trade offs. But it looks like it is worth a
few experiments.
Did you realize you sent this back to SRS instead of DPRG? ;-)
--
Jeff Sampson
http://tcrobots.org/members/jsamp.htm
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