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Old January 7th 04, 05:32 AM
Craig Buck
 
Posts: n/a
Default Matching at the antenna/line junction

I am confused by an issue and hope some of you gurus can help.

I understand matching at the transmitter end. Using the "right" length of
line or an antenna tuner - oops, I mean conjugate matching device, I can get
the rig to put all or as much power as it can into the line. If I choose
ladder line, it has very low loss in the line itself. So far -- so good.

But what happens where the line hits the antenna? If the line is 50 or 450
ohm and the antenna is exhibiting 2 ohms, isn't there a big mismatch and a
lot of lost power? How much? Would the 450:2 mismatch lose more power than
a 50:2 mismatch and thereby give up the advantage gained by the low loss in
the 450 ohm ladder line. I don't see this quantified in the antenna
modeling programs.

I realize in multiband use, the mismatch will vary so there is not a whole
lot you can do except put the tuner at the junction of the antenna and line.
So, why isn't that the "normal" way to handle the problem?
--
Radio K4ia
Craig "Buck"
Fredericksburg, VA USA
FISTS 6702 cc 788 Diamond 64