A receiving antenna exposed to the far field,
receives plane waves (essentially flat wavefront).
If you 'play the film backwards', does a
transmitting antenna emit plane waves?

"Fractenna"
They end up that way.

Soooooo... ...the wavefront in the nearfield is now flat smirk so that it
matches the flat wavefront in the receive case ?

Reciprocity is a fundamental aspect of antenna theory.

Only if someone can explain the above discrepancy.

It seems apparent that one might arrange an array to exploit the difference
between the flat (far field) incoming wavefront in the receiver mode and the
obviously-curved wavefront (near field) being emitted in the transmit case
to produce significantly different macro performance characteristics.

In other words, playing the film backwards doesn't work.



Bob,

When I was a lil squirt, we had something called a 'ripple tank'. It showed how
the film works backwards.

73,
Chip N1IR