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Re: [TowerTalk] Top loading HF-6V for 160

To: Michael Tope <>
Subject: Re: [TowerTalk] Top loading HF-6V for 160
From: Jim Lux <>
Date: Sun, 21 Oct 2007 07:26:53 -0700
List-post: <>
Michael Tope wrote:
> ----- Original Message ----- From: "Jim Lux" <>
>>> radiator height, ground loss resistance) and then let the optimizer spit
>>> out an optimum position for the center loading inductor and a optimum
>>> length for the top hat wires.
>> 4nec2 can probably do the optimization.  If you can write algebraic
>> equations for the parameters in a NEC description in terms of a few
>> symbols, it can optimize..
>> For instance, I've done a bunch of models where I was looking at things
>> like inverted Vs, where I constrained the height of the center, the
>> height of the two end supports, but allowed the spacing of the end
>> supports to vary (effectively putting more or less non-conductive string
>> inbetween the end of the V and the support).
> Yeah, that sound like what is needed. Start the optimizer, go have
> lunch, and then come back to see where to saw the aluminum tubing :-)

Something along those lines...

I thought about this a bit yesterday.  4nec2 can alter physical 
parameters (including the value of the loading inductor), but I'm not 
sure how to set it up to get what you want in one step.

You've got a center loading inductor (or, more properly a middle loading 
inductor), but do you want the feedpoint impedance to be 50+j0, or, are 
you willing to let the input Z vary, and all you want to do is optimize 
the radiation efficiency?

SO your optimization parameters would be the length of the top hat 
wires, and the angle you take them off at, the position of the center 
loading inductor, and its inductance.  You'd optimize for field strength 
(for a constant excitation power) at some low elevation angle, I assume?

You could run several optimizations with different tophat topologies 
(3,4,5 wires, whether or not they're spiderwebbed, etc.)

This is an interesting optimization problem.. clarify what you're 
looking for and I'll grind on it a bit more.

> 73, Mike W4EF................


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