Cecil Moore wrote:
Jim Kelley wrote:

What difference would it make, Cecil? One that is short compared to
the delay.


What difference would it make if the frequency of the
pulse is far removed from the operating frequency?
What difference would it make if the frequency is far
above the self-resonant frequency? What difference
would it make if the inductance is completely
swamped by the capacitance? Shirley, you jest.

The advantage to using pulses is that they are 'broadband' - they
don't have "A" frequency. The inductance and capacitance of the
system are unaffected by the small signals one impresses upon it.

What's different about the 'situ' during steady state that causes
electromagnetic fields to propagate differently than at other times?


They don't propagate differently but how does one separate
the forward wave from the reflected wave on a standing-wave
antenna? If you can do that, you will have solved the
measurement problem.

The antenna behaves physically in exactly the same way whether or not
it happens to be 'occupied' by waves, standing, sitting, or whatever
during measurement. If you want to know how long it take an
electromagnetic wave to traverse a conductor in any shape or
configuration, you pulse it and measure how long it takes, either to
get from one end to the other, or to be reflected back from the other
end. There are of course dispersion effects, and by studying the
change in the waveshape it is possible to deconvolve the frequency
dependent components. This is a matter of routine for practicioners.

73, ac6xg