re: [SI-LIST] : Diff measurements with VNA

fabrizio zanella (fabrizio=zanella%eng%emchop1@fishbowl02.lss.emc.com)
Wed, 25 Feb 98 11:36:15 -0500

Katie,
how many ports are you trying to measure, two or four? What is your
frequency range?
If you need more than 2 ports, multiport measurements with a VNA is not an
easy task. I had looked into it a few years ago, and at the time you could
only take 2 port measurements with a VNA. None of the manufacturers (HP,
Wiltron) could support multiport measurements with a VNA, so you could only
measure return loss, insertion loss, and coupling between 2 lines.
I do know that a couple of engineers have written software and created
hardware to create a multiport network analyzer, but I believe these were
internal efforts, so you'd have a hard time purchasing an off the shelf
solution.
If you only need two ports, to measure differential reflection of the pair,
you will still need to find some software which can take one of the VNA
signals and invert it in phase, to create a differential pair. Any
thoughts on this?
I remember there used to be a newsletter on VNA measurement techniques
called 'MAMA's Notes', I don't recall who published it. I would try your
HP sales rep, ask for application notes and companies they may be working
with that have done this before.

Hope this helps
Fabrizio Zanella
Hardware Engineering
email: fzanella@emc.com
(508) 435-1000 Ext. 4645
Fax: (508) 435-8949
EMC Corporation
171 South Street
Hopkinton, MA 01748-9103

-------------
Original Text
From: "Katie Rothstein" <Katie_Rothstein@notes.teradyne.com>, on 2/25/98
11:10 AM:
To: smtp@Eng@EMCHOP1[<si-list@silab.Eng.Sun.COM>]

If anyone could point me in some direction regarding differential
measurements
with a Network Analyzer I would greatly appreciate it. I'm starting from
the
ground floor here, so thoughts, information, or possible sources would be
helpful! Thank you!
-Katie Rothstein
Teradyne, Inc.
(603) 791-3488