View Single Post
  #3   Report Post  
Old May 3rd 06, 09:19 PM posted to rec.radio.amateur.antenna
Roy Lewallen
 
Posts: n/a
Default A little more on missing degrees

Dave wrote:

Where is the other 74 degrees?? This is the question that started this
2 month discussion.

Is there a fallacy in Corum's paper?

Does Corum's paper apply to a combination of a loading coil and
radiating elements?

My reasoning is as follows: if I draw a phasor diagram, I have +10
degrees phase shift from the feed point to the base of the coil. I can
then assume a +90 degree phase shift in the coil, classical inductive
response; then, the 'stinger', from the top of the coil to the tip of
the antenna produces a net -10 degree phase shift from both inductive[+]
and capacitive[-] effects resulting in a net 90 degree phase shift for
the full eight foot antenna.

Am I being too simplistic?

I conclude that I have a 16 degree long antenna with a feedpoint
resistance of ~13 ohms [ Rr = ~1.0 ohm and Rloss = ~12 ohms] with zero
ohms reactance [resonant]. [And that the phase shifts stated above are
fundamentally correct.]


You don't need to go to anywhere near that much trouble. If you replace
the stinger with a lumped series RC to ground with the same impedance as
the stinger, you'll get nearly the same currents, both magnitude and
phase, at the top and bottom of the coil as you did with the stinger. No
"missing degrees" -- no "degrees" at all, in fact. No forward and
reverse traveling waves, no standing waves. No smoke and mirrors, no
bafflegab. Just plain old circuit analysis.

Roy Lewallen, W7EL