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.
Steve

"Bruce" wrote in message ...

I ended up building two wi-fi parabolic antenna. the first a 300 mm
screen-wire dipper (used for frying bananas) measured 300 mm in
diameter and about 90 mm deep. Later built a second dish using a 430
mm aluminum "wok" about 100 mm deep.

The first antenna gave a better signal then the adapter but the second
antenna gave, using the instruments available to me, approximately 3
times the signal that the bare wi-fi "adapter" had.

As I previously mentioned I do not have a signal strength meter and
used the standard Linux utility "iwconfig" to produce some sort of
data. It gave a reading of 6 for signal strength using the bare
adapter and as high as 23 with the wok I can only assume that whatever
the value of the increments that the ratio is accurate.

As luck would have it, I found an abandoned TV "cable" antenna - as
used here "cable" is received on a 3 foot dia. parabolic antenna and I
will probably try that at some later date.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)