There's a bit of a semantic problem here, but the radiational
characteristics of that short whip do not change. You may vary how much loss
you have due to the placement of tuning elements, but it is still a short
whip, and will have the bandwidth charactistics and radiation resistance
characteristics of a short whip. No tuning elements can increase the
radiation resistance or the bandwidth. Those are better referred to as
"electrical" charactistics. If you use that to describe feed impedance or
other characteristics dependent on your chosen tuning device, just what do
you call the radiation resistance and bandwidth charactistics which are not
dependent?
Strictly speaking, you did not change the resonance of the whip. You
inserted tuning devices at a point of choice which enabled you to feed power
to the antenna SYSTEM at a chosen impedance, no more or less a tuner than a
tuner "box" at the end of a feedline. The difference is that you have
DISTRIBUTED the elements of a tuner in the antenna system for better effect
and efficiency.
You can say that you increased (the appearance of) the electrical length by
inserting a coil, and most people will know what you mean, but it is a loose
and sometimes confusing misuse of the term unless you tag "apparent" on it.
73, Guy.
----- Original Message -----
From: <K3BU@aol.com>
To: <towertalk@contesting.com>
Sent: Tuesday, November 20, 2001 9:16 AM
Subject: Re: [TowerTalk] MFJ ARTIFICIAL GROUND
>
> In a message dated 11/17/01 8:05:30 AM Eastern Standard Time,
w8ji@akorn.net
> writes:
>
> >
> > My point is simple.
> >
> > One of the big common myths in antennas is that a simple
> > inductor in series with a line, or a combination of series
> > components, can change "length" or make an antenna (or in this
> > case ground lead) "longer", or a different "electrical length".
> >
> > That myth isn't true. Transforming impedance requires both shunt
> > and series reactive components, and there is no way to get a shunt
> > component when working with two terminal devices like this.
> >
>
> So when I insert loading coil 2/3 up in the mobile antenna and bring it
> (shorter physical length) to resonance on desired frequency what kind of
> "length" is it?
>
> Yuri, K3BU/m
>
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