Jim Kelley wrote:
On May 14, 7:44 pm, Cecil Moore wrote:
In order to get a valid measurement of the delay
through a coil, the coil needs to be loaded with
its characteristic impedance to minimize the
reflected current.
What if a 3' long stainless steel whip is loading the coil?
That makes the antenna a standing wave antenna. Here
are the characteristics of standing waves vs traveling
waves for 1/4WL of wire. The phase of standing wave
current is useless for phase measurements because it
it fixed very close to zero degrees over the entire
antenna.
http://www.w5dxp.com/travstnd.gif
Standing wave current has a negligible phase shift in
the coil or in the whip and therefore cannot be
used to measure the delay through a loading coil.
To the best of my knowledge, all attempted phase
measurements reported on this newsgroup, on current
through a loading coil have been made using standing
wave current with its fixed phase. No useful coil
delay information can come from such measurements.
--
73, Cecil
http://www.w5dxp.com