Hi, Gentlemen -

I have an HP 8405A Vector Voltmeter. I have the App Note "Measuring Complex
Impedance" by HP (thanks to Wes Stewart). I have made a few measurements
following (maybe) the HP paper. I have probably been sloppy with the setup
and procedure because I came up with a negative resistance a couple of
times.

The HP paper discusses negative resistance but does not mention where one
would encounter it. I assume it would normally be associated with active
device measurements. Is this true? If I measure a (passive) load and find
that the resistance is negative, shouldn't I doubt my setup and/or
procedure? Is there any condition where a passive, real-world, network could
show a negative resistance?

By the way, I have not gotten a negative resistance reading while using a
dual directional coupler. I have gotten the negative resistance reading only
when using the power splitter method. So far.

Thanks for any insight on this.

John KD5YI