Richard Clark wrote in
:

On Mon, 26 Mar 2007 02:35:51 GMT, "David Hooker"
wrote:

Hi David,

Presumably, you are speaking of
a pocket-sized, keyring-attached
receiving antenna too, such that it can resolve the point of
transmission to a fairly narrow region.

It would take an especially large pocket to accomplish (not even a
'roo's). Such a design demands complexity in the form of volume at
the scale of 2 meters. You are off by a scale of 100 or so. Perhaps
if your frequency was set to 15GHz....

Why not, due to the close range, think inverse square law instead of
directivity? Could still be a bit confusing in an underground carpark,
but basically, the source and the receiver are close enough that a few
steps ought to make a readable difference in strength. Just walk in a
circle and keep widening it on the side where the signal is strongest and
narrowing where it is weakest. The closer you get, the less sensitivity
you need, so have some method of turning that down. And 100mw is LOTS of
power for this!


--
Dave Oldridge+
ICQ 1800667