Szczepan Bia³ek wrote:
So now I know what I want. Do you agree with Dr.?

The superposition of coherent waves is a linear function.
Therefore, there is no way for the superposition process
itself to produce harmonics.

For frequency doubling to exist, there must be a nonlinear
process. The question is: Does any nonlinear process exist
between the linear transmitting antenna and the linear
receiving antenna?

I once heard a pile of tin cans talking to me. Turns out
some rusted junction in the pile of cans was detecting
the FM from the local radio station. That was a non-linear
process. Lucille Ball is reported to have picked up Japanese
CW signals through the fillings in her teeth, again a non-
linear process.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com