Thread: SWR - wtf?
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Old June 28th 05, 07:36 PM
Scott in Baltimore
 
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For a NGP antenna, the shield is the counterpoise, and if you change the
length of that, you'll detune the antenna. If you can alter things by
moving the coax around, you've got a problem. Think of coax as a
"signal hose". The RF should stay inside of the coax, not run along
the outside and affect things. If things change, start by fixing your
ground. That's one reason I took my antenna off the magnet. The other
was so that it won't get knocked over by a low branch on the trail.



And one last thing,

The speed of the signal INSIDE the coax (the velocity factor) is slower
then the speed of the signal OUTSIDE (on the shield). While 17.21 feet
is a quarter wave on the outside of the shield, the inside 1/4 wave is
shorter. If you want to see the actual SWR at the feedpoint, then use
a 1/2 wave electrical length of coax. This will shift the phase of the
mismatch back into it's original position at the other end of the feedline.

(I learned all this stuff while I was still a single bander, and still
laugh at all the ham's that still believe the coax length BS.)

I don't dislike CB. It's another band to use. I dislike all the noise on it now!
If I can't find someone to talk to on one band, I've got others to use now.

BTW, repeaters suck! I've only got to abide by Part 97, not what some control op
thinks his interpretation of the rules are. I'm simplex only these days.

(Sorry, no letters or warnings have been recieved by me! I just said **** it.)
And I didn't say that on the air!!!!!!!!!!!!!