GPS Problems near CHD..

As a followup to my previous post on 396 GPS reception problems, has
anyone noticed GPS reception issues around the Chandler, AZ airport?
As soon as I leave the ground, I seem to always lose satellite lock on
my Garmin 396. I lose satellite lock like crazy in the pattern. Leave
the area, and everything is fine. Throughout 2 cross countries, not one
problem with the satellite. Get near CHD (and once on the ground at
FFZ) and problems are guaranteed.

It's not the on-board radios, since this has happend in 2 different
aircraft, and in one of them, the only radio in use was a GNS 430.
(430 did not lose sat lock).

Maybe there is some kind of interferance, although this pattern of
behaviour is very strange!

--Dan