[Top] [All Lists]

[antennaware] RE: SWR from R,X,Zo

To: <>
Subject: [antennaware] RE: SWR from R,X,Zo
From: (Dallas Carter)
Date: Wed, 4 Aug 1999 11:09:14 -0400
Dave, Thanks a million for the help.  That's exactly the formula that I have 
been searching for.
It is correct and plugs into basic very nicely.  Now I can continue with my 
xmission line
matching and find values that yield acceptable matches with the help of W4RNL's 
tutorial on the subject.  73  Dallas  W3PP

From:   Leeson[]
Sent:   Wednesday, August 04, 1999 9:02 AM
To:     Dallas Carter
Subject:        SWR from R,X,Zo

Here's the formula derivation for SWR from known R, X and Zo:

Reflection coefficient  refl = sqrt[((R-Zo)^2 +X^2)/((R+Zo)^2 +X^2)]

SWR = (1+refl)/(1-refl)

You can combine these two formulas into one for SWR

SWR = {1+sqrt[((R-Zo)^2 +X^2)/((R+Zo)^2 +X^2)]}/
                        {1-sqrt[((R-Zo)^2 +X^2)/((R+Zo)^2 +X^2)]}

Try this out with various values for which you know the SWR to be sure
I've gotten all the details right.  For example,

For R = Zo, X = 0, refl = 0 and SWR = 1

For R = 0, X = Zo, refl = 1 and SWR = infinity

For R = X = Zo, refl = 0.45 and SWR = 2.62

Give this a try...

73 de Dave Leeson, W6NL/HC8L

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>