I am posting this on this reflector because I know a number of the readers
[and writers] have the AIM-4170 . We also have some very brilliant thinkers
and extremely competent experimentalists in the group.
Users of the AIM-4170 are aware of how to run a special calibration on a
length of coax line used to feed an antenna. Then they are able to make
measurements at the station end of that line and transform those
measurements to ones that apply to the impedance the other end of the line.
This is useful if you wish to know what the antenna feed point impedance is
without inserting the AIM-4170 into the feed point to do the measurements.
I would like to know if anyone can tell me how to use the AIM-4170
instrument to make a measurement at the feed point and then predict what the
impedance will be at the station end of the feed line. Further, what if the
feed line goes through a filter and/or passes by a 1/4 wave stub on the way
from the feed point to the transmitter? Can we still predict the station fed
point impedance from a measurement of the antenna feed point impedance.
Previous measurements might need to be made on the line and filters etc.
that are between the feed point and the station.
If one could do this it would be possible to make adjustments to a network
at the feed point of a vertical and then know what the impedance would be at
the station when using CATV line as the feed line and the length of the line
was not a multiple of 1/2 wave at the frequency of interest. There are
likely to be other applications as well.
All ideas welcomed --- math equations are OK. The boundary conditions are:
1. All measurements are to be made with the AIM-4170.
2. Transformations of the measurements to final results should be done with
existing programs [preferably not MATHCAD].
Tod, K0TO
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160 meters is a serious band, it should be treated with respect. - TF4M
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