Topband: Dumb radial question

[Tom Rauch]

> 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