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Old March 3rd 04, 10:09 AM
Gordon Couger
 
Posts: n/a
Default SWR Meter for very short ballaced linds

I am working on the design of a sensor that needs to measure the
forward and reflected power in unison at or very near the feed point
of the antenna drive by a very short 4 inches of less feed line over a
range of 10 to 100 Mhz at power level less the 100 ma. The feed lines
will be potted in a plastic to water proof it so the sensors will be
embedded with them.

The ideal solution from a manufacturing and calibration point of view
would have the antenna come right out of the network of the amplifier
with no feed line to act as a transformer over a wide range of
frequencies.

This is not a class project as most of the regulars know I well beyond
that by nearly 40 years.

I can see a number of ways how to do it with a coaxial feed but open
wire is less expensive and easier to manufacture and make repeatable.
I realize at least the reflected power will have to amplified to be
measures by equipment in my price range.

I seem to remember that a piece of open line placed parallel to the
driven line and properly terminated will read voltage nodes on the
line and possibly the forward and reflected power. It has been a very
long time since I read that and was not paying much attention at the
time. I think it was in a CQ when it was still in the small format
with Wane Green as editor.

Any help or ideas welcome.

Thaks
Gordon Couger W5RED