Harry wrote:

What does it mean by "when the pulse is *differentiated* by the
transmitting antenna" ?

Mathematically it means to take the derivitive, or evaluate the slope of
a time varying quantity. Electronically it means the antenna acts as a
high pass filter - effectively blocking DC and attenuating low frequency
signals.

jk

Cecil Moore wrote:

It means that steady-state DC is incapable of generating photons.

You forgot about the flashlight again, didn't ya Cecil. Photons are
generated when the steady state DC source is applied to the light bulb
inside. They are allowed to escape through the clear part in the front
of the flashlight. :-)

By the way, my nephew just graduated from UCSD with a bachelors in
Photonics Engineering. He told me that the photonics engineering
discipline is virtually all applied wave mechanics.

ac6xg