On Wed, 19 May 2010 09:32:26 -0700, John Navas
wrote:

On Mon, 19 Apr 2010 22:28:25 +0200, "Steve Lusardi"
wrote in :

As I stated Bruce, the TV antenna is a good plan. It will be a true parabola and the gain over what you have will be significant.
Don't forget about the 30 degree included angle that is built in. You will have to move the detector up to the center for your
application.

The shape of the antenna is not critical -- in practice a typical curved
bowl will work pretty much the same as a carefully constructed parabola.

Since I wrote the original I have done more research and it appears
that the current favorite is the offset feed dishes. One article has a
method of calculating the reflection angle and then cutting a string
for the far side of the dish and a second for the near side and mount
the feed at the point that the two strings meet.

Also I found several articles abut the construction of double quad
antennas and one of the articles showed the graphs of test with 12 db
gain.

I may change to the quad if I can get that much gain from a smaller
antenna as none of the tests I saw indicated that the dish produced
really astonishing gain.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)