[TowerTalk] Modeling antenna traps

[Timothy Holmes]

Hi Jim

I guess that goes to the crux of my question, how do I go about measuring
those parameters, and, once I have done so, how do I then model them. This
is turning into quite an interesting discussion.  I should mention that I
have an MFJ antenna analyzer with the grid dip coils if that will help, as
well as a multimeter

TIM
W8TAH

On Sun, Jun 5, 2016, 6:33 PM Jim Brown <jim at audiosystemsgroup.com> wrote:

> On Sun,6/5/2016 1:20 PM, Timothy Holmes wrote:
> > I would like to model them so that I can properly adjust them to see if
> it
> > is even worth my time, and what the performance will roughly look like
>
> To model the antenna, you will first need to measure the traps to find
> their complete equivalent circuit. A trap is fundamentally an inductor
> with series resistance in parallel with a capacitor with parallel
> resistance. Near resonance, they simplify to parallel R, L, and C, but
> above and below resonance, we need to know the R in series with L,
> because these values affect performance on bands below the resonance of
> the trap. And, of course, both Rs vary with frequency, thanks to skin
> effect.
>
> 73, Jim K9YC
>
>
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