RadioBanter - View Single Post

March 15th 06, 01:17 AM posted to rec.radio.amateur.antenna

wrote:
John Popelish wrote:

To get the power in the reverse direction, the input and output are
effectively exchanged so that the forward power indication cancels and
the reverse power indication is produced by the sum of its voltage and
current d-c sample outputs.

Thank you for this concise summary.

Except it is actually an incorrect concise summary.

The directional coupler adds RF voltage from a sampling across the line
directly to a sampling of RF current past that point.

It is only after the voltages, one proportional to current and one
proportional to voltage, are added that the resulting voltage is
rectified and used to drive a meter.

The directional effect can be analyzed using wave theory or simple
circuit theory. The results are the same.

I appreciate the correction. I am weak in the area of RF
instrumentation, but am learning fast. It is an area I have somehow
avoided for a long time, but am getting interested in it, lately.

I would very much like to see a more complete report on the
measurements you have made, in relation to this thread. I am sure I
would learn from seeing that. I tried to find an operating manual or
application note on the network analyzer you used, but found little
that was helpful to teach me how it works, and how one applies it. It
seems to have 4 signal connectors (if I am interpreting what I have
found, correctly) and I can interpret your web account to mean several
possible things, so I am still under a bit of a cloud, here. Your
tutelage is much appreciated.