Chip,
N1IR wrote:
"They end up that way (as plane waves at a great distance from the
radiator). Reciprocity is a fundamental aspect of antenna theory."

Dr. Cohen is, of course, correct.

Dr. John D. Kraus says in his 3rd edition of "Antennas" on page 439:
"If an emf is applied to the terminals of antenna A and the current
measured at the terminals of another antenna B, then an equal current
(in both amplitude and phase) will be obtained at the terminals of
antenna A if the same emf is applied to the terminals of antenna B."

Best regards, Richard Harrison, KB5WZI