Richard Harrison wrote:
Relative to the impedance of a reasonable antenna. the impedance of the
atmosphere or the impedance of free-space is non-conductive.
When the signal following the conductive surface of an antenna reaches
its end of the conductive path, current reverses its direction of travel
of necessity.

Maybe better understood using visible EM waves.
When the medium's index of refraction changes,
reflections are the result. One can learn a
lot about EM wave reflection by looking in a
mirror. With some of the strange concepts about
EM reflected energy that exist on this newsgroup,
it is a wonder how the promoters of such concepts
can look themselves in the mirror. :-)
--
73, Cecil http://www.w5dxp.com