Using Return Loss Bridge to measure Impedance

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Sam Wetterlin
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Joined: Sat Apr 28, 2018 6:48 pm

Using Return Loss Bridge to measure Impedance

Post by Sam Wetterlin » Sun Nov 30, 2008 4:06 pm

Hi All,



I have posted a couple of files on my website describing a method to

use a return loss bridge (aka reflection bridge) to measure impedance,

even though return loss is a scalar quantity and impedance is a vector

(i.e. 2D) quantity. It doesn't have the automation or precision of a

VNA, but it provides a nice estimate of impedance using just a signal

generator and return loss bridge, with a spectrum analyzer or other

method of measuring the bridge output. The process involves taking a

few manual measurements at one frequency and entering the measurements

into a spreadsheet. The spreadsheet graphs 3 circles, whose

intersection shows the device impedance.



The method and some test results are described in





The Excel spreadsheet used for graphing is at





(I tried to convert the Excel spreadsheet to Open Office, but the

chart sheet would not properly convert.)



Sam W.

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