View Single Post
  #568   Report Post  
Old March 22nd 06, 01:40 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
Posts: n/a
Default Current through coils

Ian White GM3SEK wrote:
The only thing those people have in common is a desire to get the facts
right...


I have asked you guys to explain the technical facts behind
about a dozen technical questions of mine. The silence has
been deafening. Many readers of this newsgroup have noticed
the same thing.

Here are the technical facts about the two models. At one end
of the spectrum, we have lumped inductance. At the other end
we have physically huge coils. The crossover point where the
lumped circuit model becomes invalid is about 0.04 wavelength.
A mobile antenna is a lot longer than that. At lengths above,
0.04 wavelength, standing waves have to be taken into account.
The lumped inductance model cannot take standing waves into
account. It assumes instantaneous faster-than-light propagation
of current.

DC|-------------distributed network model valid----------------|

DC|---lumped circuit model valid---| 0.04WL cutoff

Here are the two main technical points:

1. Nothing valid is proven by using standing wave current phase
to measure anything. Gene F. and Tom D. seem to realize that.

2. The taper of the standing wave current through a coil
depends upon where the coil is placed in the standing wave
environment. You guys have looked only at mobile antennas.
Try looking at longer antennas like the one at:

http://www.qsl.net/w5dxp/current.htm

You will find that the current taper through a coil can be
zero, positive, negative, or even reverse phase. The phase
reversal can be considered to be current flowing into both
ends of the coil at the same time.

Please come out of the deep dark lumped circuit cave and
see what the rest of the world is like. You guys have been
seduced by your model. You have assumed the presuppositions
of the model are valid without technical proof.

Here's an analogy:
Ian W. says: I believe water is one of the basic elements and
as proof, I offer a quart of water.

Roy L. says: I believe earth is one of the basic elements and
as proof, I offer a bucket of earth.

Tom R. says: I believe fire is one of the basic elements and
as proof, I offer this burning torch.

Richard C. says: I believe air is one of the basic elements
and as proof, I offer this balloon full of it.

Cecil says: I believe there are over 100 elements and as
proof, I offer this periodic chart of those elements.

I will be on spring break until Monday so don't think I have
given up on getting the technical facts out there for all
to see.
--
73, Cecil http://www.qsl.net/w5dxp