[TowerTalk] mismatch loss and SWR

[K4SB]

w8ji.tom wrote:
 
> Hi Steve,
> snip Antenna VSWR does reduce antenna gain.No question.

Tom, I hope you will look at that sentence again. This thread is 
getting to the point where we're misleading a lot of people.

There is no such thing as Antenna VSWR. There is something called
VSWR and it pertains ONLY to the impedance of the feedline, the 
impedance of the load, and the output impedance of the generator.

Antenna gain is not reduced 1 bit by VSWR. If we have an antenna with
6 dbd gain, with or without the feedline connected, it still has 6
dbd gain. VSWR on the other hand, depending on a variety of conditions,
can and does reduce the generator power delivered to that antenna.

BUT, if you lose 500 watts in the feedline, or 5 watts in the feedline
( assuming the generator output is proportional in both ), that antenna
still will be radiate the power delivered to it by a factor of 
Power X 6 dbd.

And if you hang your Alpha from the antenna, VSWR by definition, will
no longer exist. A mismatch between the 50 ohms of the Alpha and the
antenna may exist, but if we change the Alpha to one of the older rigs
with an adjustable coupling loop, the power loss will be practically
non existent. 

Digressing for a moment, I am surprised amps haven't been made for the
exact purpose of mounting on the tower.

73

Ed

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