Hi Paul,

I don't mean to pick on you, but... you really should become more
familiar with VNA measurements in general. You should be able to find
documentation on the web; try the Agilent site for example, and look
for VNA ap notes. I downloaded some recently, so I'm pretty sure they
are there. A VNA is a wonderful piece of test equipment, but it won't
give you answers you can trust if you don't understand it. I would
trust what they tell you (or similar from R&S or other reputable
manufacturer) more than I would trust replies here to be not only
accurate but complete.

For example, you should understand that your dummy load could be
considered a two-port device where S21 and S12 will be very
low--hopefully vanishingly close to zero. If you connect it to port 1,
you should get a valid indication of S11. You should expect S22 to be
unity or very close to it, if that port is left open or shorted. (But
why would you even bother to ask for S22, or S21, or S12?)

But there's another problem here. HOW do you calibrate your VNA?? You
ideally should have a precision short, a precision open, and a
precision load--best if you have calibration data for the loads. If
you measure your load, how will you know whether an imperfect S11 is
due to the load, or to the VNA? Of course, it will be to some extent
both, but it would be nice to know that the VNA is accurate to within
some tolerance.

Cheers,
Tom