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Old January 7th 04, 05:43 AM
Cecil Moore
 
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Craig Buck wrote:
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?


"A lot" needs to be defined but the short answer is yes. That's why 2 ohm
antennas are not popular. A lot of antennas are designed with close to 50
ohm feedpoint impedances at resonance.

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?


That is fairly normal now that remote autotuners are readily available.

Another way to handle the problem is to use very low-loss transmission
line, e.g. open-wire feedline which will tolerate a high SWR with relatively
low losses. The antenna *system* is then matched at the transmitter.

I personally use the open-wire feedline to transform the antenna impedance
to an impedance acceptable to my transmitter with no tuner required.
--
73, Cecil http://www.qsl.net/w5dxp



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