"Richard Harrison" wrote
The assumption was that on average, the propaqgation was nearly the same
for the signals received from both transmitting antennas. Good or bad
propagation, the difference between the signals depended on gain in the
direction of the receiver as the transmitted power was the same to both
antennas no matter where it landed.

"Propagation" has to include ALL means by which EM energy radiated from a
wire antenna finally arrives at a receiving location. That necessarily
includes the radiation effects of reflecting/obstructing objects and
surfaces, each of which may be illuminated by varying ERP from the wire
antenna -- depending on the radiation envelope of the wire antenna itself,
its installation detail, and site topology.

The ERP directed toward a particular receiving site depends on more than the
free space gain of the tx antenna along a single launch angle (which I
believe is Art's point).

RF