Hi,

I'm hoping that we've got a few RF engineers floating around that can help
me out with this.  I'm a digital systems type person, myself, but I'm
working in a place that needs me to do work on RF circuitry, so I'm a bit
stuck.

I have a relatively good hybrid coupler that was built as a power splitter.
It has -41dB isolation and -3.08dB ouput ports.

I want to use it to measure scattering parameters of a preamplifier but I
don't know how to connect it.  I know that the HP transmission/reflection
test set, which I am trying to emulate with this device, is a 4-port unit,
and that 2 of the ports go to a network analyser input, 1 port that get RF
in, and 1 port that goes to the DUT.  I do not, however know what the 2
ports that go to the inputs are.

My directional coupler has the following ports: In, 50ohms, 0 degrees and 90
degrees.  What ports do I connect to the network analyser?

I assume that the IN port gets the RF out from the network analyser, and
that the 50-ohm port goes to one of the inputs (but don't know which one),
but I don't know whether the 90-deg or the 0-deg port goes to the DUT.

Anyone done this before?

--Brendan

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