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TRM calibrations in free space

Question asked by Amiet on Jun 23, 2008
Latest reply on Jun 24, 2008 by RayH
Hi all, I've been making free space permittivity and permeability measurements for about 15 years using simple response and response/isolation cals on my 8510C. Two microwave horns point at each other, and a finite sized sample is placed between them. Time gating is used to clean up the signal, and the transmission around a metal plate the same size as the sample is used to remove (well, at least most of) the diffraction. The technique works, but I'm still interested in getting better accuracy if possible, especially for S11 measurements. I am looking into using TRM, but haven't come up with a clear definition for the Match standard. I would be using;

S11 and S22 Reflect standards - Ground metal plate, perfect reflector
Thru standard - zero length line
Match standard - convoluted anechoic chamber absorber

8510-8A discusses the parameter to be entered for TRL cal, but glosses over the details of the match standard. What parameters do I enter into the 8510C TRL calkit to identify the absorber?

Thanks,

Andrew  

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