These values are important because SWR is a measure of how well the input
impedance of your antenna system matches the output impedance of your
xmtr/feedline. Maximum transfer of power will occur when the output impedance
of one stage matches the input impedance of the next stage. Most of our radio
equipment is designed with an output impedance of 50 ohms. If this 50 ohm
output impedance is connected to an antenna system with an input impedance of
exactly 50 ohms, you get maximum power transfer and lowest SWR (1 to 1).
Impedance is made up of resistance and reactance (it's the vector sum of
these). Reactance comes in two forms, inductive and capacitive. The total
amount of reactance you have depends on your operating frequency and how much
inductance and capacitance there is. Inductive reactance acts opposite to
capacitive reactance. The two forms can be made to cancel each other out, thus
reducing the total net reactance. Changing the net reactance of the antenna
system changes its impedance, which in turn will change the SWR.
Anyway, this is the way I understand it. I'm sure others on here can shed more
light on the subject.
----- Original Message -----
From: Andrew <email@example.com>
Date: Sunday, January 31, 2010 11:29 am
Subject: [TowerTalk] Low SWR
> I have read that Reactance(X), Capacitance(C), and Inductance(L)
> readings at
> Low SWR is useful info, how so?
> TowerTalk mailing list
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