Roy Lewallen wrote:
I love the simplicity of Itot = I+ + I-. I also like the simplicity of 1
+ 1 = 2, V = I/R, and e^(j*pi) = -1. But none of these is adequate to
determine the current at the top and bottom of a loading coil.

We don't have to determine the current at the top and bottom of a
loading coil. All we have to determine is that the current at the
top and bottom of a loading coil cannot be equal in magnitude. It's
a simple true/false logic question, not a question of degree of
accuracy.

EZNEC says the currents are not equal when the helix feature is
used to simulate a real-world coil.

Your and Tom's measurements proved that the currents are not equal
except for Tom's one special toroidal case where he probably located
the current maximum point within the inductor.

Yes, and for the life of me I can't see how to use it to find the
current at the top and bottom of a coil in a simple monopole.

You don't have any equations either but that doesn't stop you from
making assertions about those currents. Why are you attempting to
hold me to a higher standard than you hold yourself or Tom? I'm
not asserting anything new. I learned the qualitative basics of this
subject at Texas A&M almost half a century ago. I'm amazed that those
basics don't seem to be taught any more.

But I'm kind of dense. Can one of the many other readers of this group
kindly explain how Cecil's equations and explanations are used to
actually figure out what the current will be at the top and bottom of a
loading coil? Yuri, you seem to understand it -- can you explain it to
me? Richard? Surely the necessary equations are in one of your books?

It is not necessary to figure out what the current will be. That is
just diverting the issue. All that is necessary for the present
argument is to show that, in the 90 electrical degrees of a mobile
antenna, that the two component phasor currents at each end of the
coil don't add up to the same value. I have done that.

Since the bugcatcher coil shifts the phase of both the forward current
and reflected current by the same amount in opposite directions, it
is impossible for the current to have the same magnitude at both
ends of the coil when the loading coil is installed at the 45
degree (center-loaded) point in an electrical 1/4WL antenna.
--
73, Cecil http://www.qsl.net/w5dxp


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