On 7/2/2015 6:53 PM, Ian Jackson wrote:
In message , rickman writes
On 7/2/2015 3:52 PM, Wayne wrote:

The attenuation at a given high SWR depends upon the the matched
feedline loss, as reflections encounter that loss with every forward or
backward trip.
Thus feedline length/attenuation should be considered.

As a young man I was given a problem of solving poor antenna performance
on an aircraft band fixed station antenna. The SWR at the transmitter
was close to 1:1, but the antenna didn't work well.
I climbed up on the tower and found that the coax had never been
connected to the antenna. That was with about 400 feet of coax at
120 MHz.

So how was the SWR 1:1?

It's probably the go-and-return loss of (say) 20dB's worth of coax (at
120MHz), with the far end open (or short) circuit. That would give you
an RLR of 40dB (an SWR of 1.02), which probably far exceeds the
capability of an SWR meter to read.
http://bit.ly/1T8TwcF
http://cgi.www.telestrian.co.uk/cgi-bin/www.telestrian.co.uk/vswr.pl

I like the comment that the antenna "didn't work well". Lol. I wonder
how much better it worked when connected. The feed line would still
have a lot of loss one way. I wonder why the power amp wasn't closer to
the antenna.

Reminds me of a time I was working a job installing TV antennas and one
was up the side of the ridge near here. In the "old days" we would
unplug the TV to prevent shocks from a "hot" chassis set. This
installation also had a wall jack for the antenna connection. The guy
on the roof told me to plug the TV in and check the signal while the
turned the antenna. The image was a little snowy, but not bad. No
matter how they turned the antenna the image didn't get much better. I
looked behind the set and saw the three foot twin lead from the set
laying on the floor. I plugged it in and the picture was *perfect*! I
was amazed a short piece of lead in could receive as good a signal.

--

Rick