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Old May 9th 07, 01:35 AM posted to rec.radio.amateur.antenna
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Posts: 342
Default Phase Shift through a 75m Texas Bugcatcher Coil

Richard Harrison wrote:
Gene, W4SZ wrote:
"The current lags voltage principle does not settle anything in this
case."

W8JI claims that current flows into a turn at a coil end/s and is
induced without delay into all turns of the coil, overcoming delay that
the coil might otherwise impose.

If that were true, Terman would have told us so. In fact, Terman tells
us the opposite is true in explaning the traveling wave tube begining on
page 678 of his 1955 opus:

"The signal to be amplified is applied to the end of the helix adjacent
to the electron gun. Under appropriate operating conditions an amplified
signal then appears at the other end of the helix.-------inapplicable
info deleted-----. The applied signal propagates around the turns of the
helix and produces an electric field that is directed along the helix
axis. Since the velocity with which the signal propagates along the
helix wire approximates the velocity of light if the frequency is not
too low (caveat is unimportant, see footnote in book), the axial field
due to the signal advances with a velocity that is very closely the
velocity of light multiplied by the ratio of helix pitch to helix
circumference."

In other words, the axial advance is much like that of a threaded bolt
as the pitch angle is always fractional. Kraus details this in his
section on helical antennas.

Best regards, Richard Harrison, KB5WZI


Richard,

I would never argue with Terman.

You completely changed the subject, so I have nothing further to say.
The line you quoted above is still correct. Feel free to continue on in
whatever new direction you want.

73,
Gene
W4SZ
 
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