On Tue, 22 Feb 2011 09:54:53 -0800, Jim Lux
wrote:

Here we have three (3) antennas, and as we all know they are not in
isolation.

Somewhere, there's a nearby (or near enough) overlooked reflective
surface that disrupts that oh-so-absolutely-necessary symmetry.


All practical systems like this use some form of adaptive logic to fix
that. Usually, adaptive canceling is done in the receiver, because the
signal levels are lower, but in the 802.11 kind of world, with 100mW
linear transmitters, there's probably not much cost difference.

A different matter if you're running a kilowatt.

It only takes a couple of milliWatts (kiloWatts aside) to ruin your
day in competition for listening to microWatt signals. The desired
signal's transmitter antenna would have to be literally within the
near field of the active transmitter (and receiver's) antenna system.
At that point, we may as well use a land-line with hybrid bridges.

Software coming to the rescue for a hardware problem works only in
multi-million dollar projects (fly-by-wire avionics comes to mind).

73's
Richard Clark, KB7QHC