N0GW wrote:
. . .
So... Yes the antenna is a transducer. No, it does not transform 50
ohms into 377 ohms. 377 ohms refers to the eletrostatic and magnentic
fields as they exist in the near field of an antenna or conductor. It
does not refer to what is going on electrically in the antenna
conductors.
. . .

377 ohms does not describe the E and H fields in the near field. 377
ohms is the ratio of E to H in the *far field* when the medium is free
space or, for practical purposes, air. In the near field, the ratio of E
to H can be not only far from 377 ohms, but it's commonly also complex
(that is, E and H not in time phase). For an illustration, model a short
dipole or small loop with EZNEC or NEC-2, and use the near field
analysis to find E and H at some point close to the antenna (within a
fraction of a wavelength). When you divide E by H, you'll get a wide
variety of results(*) depending on the type of antenna and the
observation point. But as you get farther and farther from *any*
antenna, you'll find that the ratio always converges to 377 ohms, purely
real (that is, the E and H fields in time phase).

(*) The ratio of E to H is called the "wave impedance". In the far
field, and only in the far field, it equals the intrinsic impedance of
the medium. And, as Gary and others have said, this shouldn't be
confused with the ratio of voltage to current at an antenna feedpoint.
They are not at all the same thing, in spite of having the same units of
ohms.

Roy Lewallen, W7EL