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Old December 3rd 07, 03:22 AM posted to rec.radio.amateur.antenna
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Default Tom's experiment

"AI4QJ" wrote in
:

I ran W8JI through the corum calculator. I got a super-well tuned
calculation of several coil parameters that I assume to be correct for
now, and surprise, phase angle is still close to 90 degrees (what else
could it be?). The beta axial propagation factor is 2.122 rad/m. I am
trying to figure out the significance of that; it looks like a
velocity factor correction relative to a traveling wave in a vacuum???


You have to view the helix as a transmission line.

The phase change along the transmission line representation of the helix
is 2.1 rad/m, so along 0.254m, there is a phase change of 0.53 rad or 30°
in waves travelling along the line.

To help get your mind into gear, solve this problem:

You have 4.124m of RG58C/U, the far end is s/c, what is the apparent
inductance at 4MHz looking into the line.

Did you get 1.1uH?

What is the electrical length of the line?

What is Beta?

Now apply the same thinking to the helix transmission line equivalent.

Owen
 
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