[TowerTalk] Low SWR

[Blair S Balden]

Hi Andy,
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.
Best regards,
Blair NP2F

----- Original Message -----
From: Andrew <wa9_kpz at att.net>
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?
> 
> 73,
> 
> Andy
> 
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