A 30 dB return loss is nothing to sneeze at.
-John
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Correction! We are seeing this with a good load attached, no calibration.
Same load gives different curve for each port.
I would expect the reflected power to be much lower than -30 dBm.
Of course with the open or short the reflected is close to 100%.
Too much egg nog.
--- In hp_agilent_equipment@..., "Peter Bunge" <bunge@...>
wrote:
Merry Christmas all!
My friends and I have been comparing what we see from the S Parameter
Test Set on the two ports. These tests are with the VNA uncalibrated and
with proper opens or shorts (even from APC7 cal kits).
Typically we get completely different shaped curves ranging from -35 to
-55 dB.
I get very similar results using the same S Parameter Test Set on an
HP8753B and an HP8753C so the curve shape is caused by the test set not
the VNA.
Typically we see one port 10 dB better and flatter than the other.
Any comments?
p.s. the cal kit discussion was very informative and timely. I still
don't understand the comment (that was later corrected) about the open
usually missing a part. My friend's Type N cal kit does not have extra
parts for the open. Also I have seen an open/short combo advertised and
wonder if this comes apart to use the open??? I have not used one and
find the concept of one end a short (OK) and the other an open (how?)
confusing.
