On Feb 17, 7:01*pm, Richard Clark wrote:
On Thu, 17 Feb 2011 19:39:19 -0600, tom wrote:
On the other hand the null for this antenna array would need to be maybe
90dB or better to be really useful.

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.

73's
Richard Clark, KB7QHC

About 25 years ago, I attended a conference on design methodologies
for blanking continuous (or high duty factor) signals in a military
environment. The benefit is to eliminate interference by your own
transmit signals to receivers, especially wideband EW/ECM receivers.
No discussion of twinned transmit antennas, though, but sample-and-
cancel techniques were prominent. Big problem: maintaining phase
linearity.