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Old November 5th 03, 07:22 AM
Mark Keith
 
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Roy Lewallen wrote in message ...
No, I will make one more comment. After a bit of reflection, I think
this might be at the core of some people's problem in envisioning a
lumped inductor.

When a current flows into an inductor, it doesn't go round and round and
round the turns, taking its time to get to the other end. An inductor
wound with 100 feet of wire behaves nothing like a 100 foot wire. Why?
It's because when the current begins flowing, it creates a magnetic
field. This field couples to, or links with, the other turns.


This is the way I view it, and why I couldn't automatically endorse
the fairly large difference they saw. Unless the coil is very long,
say as in a helical whip, I see it acting pretty much as a lumped
inductor. Sure, the current may vary some through the coil when it's a
foot or so long bugcatcher coil, but I don't see it being a major
issue. I wouldn't normally expect to see a sharp current taper across
the coil. I see that type of coil acting much as a "one piece" lumped
inductor, not as a many turned rf roller coaster ride. Not a perfect
lumped inductor, but close enuff for average gov work. MK