Electronics World Cover,TOC,and list of posted Popular Electronics articles QST Radio & TV News Radio-Craft Radio-Electronics Short Wave Craft Wireless World About RF Cafe RF Cafe Homepage RF Cafe in Morse Code Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Manufacturers & Services Consultants Engineer Jobs Twitter LinkedIn Advertise on RF Cafe! Engineering Books Crosswords Engineering Humor Kirt's Cogitations Engineering Event Calendar Day in History RF Engineering Quizzes AN/MPN-14 Radar 5CCG Notable Quotes App Notes Bookstore Calculators Education Engineering Organizations Magazines Software,T-Shirts,Coffee Mugs Articles - submitted by RF Cafe visitors Simulators Technical Writings Advertisers Websites RF Cafe Archives Test Notes Slide Rules RF Cascade Workbook RF Stencils for Visio Shapes for Word Thank you for visiting RF Cafe!

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger
BSEE
KB3UON
EIEIO

Carpe Diem!
(Seize the Day!)

5th MOB:
My USAF radar shop

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse riding website

HP87512/VNA - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Below are all of the old forum threads, including all the responses to the original posts.

-- Amateur Radio
-- Antennas
-- Circuits & Components
-- Systems
-- Test & Measurement

DIDIER40
Post subject: HP87512/VNA
Unread postPosted: Thu Nov 11, 2004 4:32 pm

I have a question for those who have 'worked' closely with the equations involved in the VNA, and particularly for the calibration procedure.
At work we have a HP8751A VNA (5Hz-50MHz) working with a
reflexion/Transmission Test Set HP87512. As I'm always loking for 'the way it work', I opened it, thinking it was a directional bridge made with 50ohms resistors (Wheastone bridge) with the design adapted to work from 5Hz to 500MHz.
But it was a great surprise for me to see that the 'bridge' from HP,made of resistors, have nothing to do with a Wheastone bridge (from what I could understand !!). With the schematic from HP, I can't manage to find a 'directivity' behavior of the 'bridge' made of resistor. As the HP8751A work with a S parameter HP87511A or B, I know that the 'bridge' is not a Voltage/Current method of measuring the reflexion parameter. And if I look on the 'mathematics' for the calibration of a VNA (TRL or SOL methods,...), there is always a correction factor for the unperfect directivity of the directional coupler.
So is it possible to obtain the correcting factor even
with a nondirective bridge, or a SOL method is able to accept a nondirectional bridge ???? It seems that the signal from the Output connector is 'split' with diferent levels to the Reference Port and the A port...
I'm in a real confusion ...!!!

If you have any idea about the way the HP87512 work with the HP8751A, I would be pleased to read you on the subject (or if you know a link with the description of the way it work,...)

Didier



Posted  11/12/2012

Try Using SEARCH to Find What You Need.  >10,000 Pages Indexed on RF Cafe !

Copyright 1996 - 2016
Webmaster:  Kirt Blattenberger, BSEE - KB3UON
Family Websites:  Airplanes and Rockets | Equine Kingdom

All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.