Richard,

Maybe someone can help us here. Linearity is well-defined in
electronics by the law of superposition, and is characterized by
well-known measurements such as harmonic generation, compression point,
and third-order intercept point. I'm assuming antennas must follow the
same law of superposition while transmitting and receiving to be
linear.

It is not clear to me that a nonlinear or even unpredictable current
distribution along a wire antenna produces signals that violate the law
of superposition. Under a strange current distribution the antenna
radiation pattern will certainly distort, but how does that violate the
law of superposition? That is, how can a strong received signal
influence a weak one on an antenna with nonlinear current distribution?

Maybe, like so many other threads in this group, we are discussing
orthogonal concepts.

73,
Glenn AC7ZN