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)