> On Wed, 25 Oct 2006 18:33:15 +0200, Vanderydt Theo wrote:
>
>>Now i read following figures from the analyzer.
>>SWR 1.5/1 X 0 and R 80 Ohms. Bandwith stayed the same at
>>about 60 KHz. SWR
>>went up a bit, but what i'm puzzled with is the increase
>>in impedance?
> would at the antenna, BUT the length of transmission line
> will tranform the R
> and X values by some complex ratio that depends on the
> length of the line. In
> other words, if you're measuring at the transmitter end of
> a length of coax,
> what you've measured is quite normal.
> Obviously, the best place to measure is right at the base
> of the antenna,
> because you don't have to go through those messy calcs. :)
Two additional points:
1.) The shunt wire itself is a transmission line. This is
what often messes people up when they try to phase shunt-fed
antennas.
2.) The resistance at the current loop in the antenna
element, even if you do know what it is, doesn't mean much
for estimating efficiency.
73 Tom
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