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# about the TRL calibration

Question asked by stone.wu on Mar 29, 2011
Latest reply on Mar 29, 2011 by Dr_joel
HI,

When doing TRL calibration, I encountered some problem. Could you give me some help?

(1)     About the length of the line

From the TRL theory,D.M. Pozar,‘Microwave Engineering’,pp 217,second edition,  There is no specification of the

Length of the line. But in agilent’s application note, they say the electrical length of the line should be

Between 20 degree and 160 degree without any reason? why?

(2)     For wideband TRL calibration

When doing wideband TRL calibration, we should use multy lines. Such as 1GHz – 50GHz, we use three lines :

Line1 1GHz-5GHz, line2 5GHz – 20GHz, line3 20GHz – 50GHz. And every line is under the specification of the

Electrical length. But after the calibration, there is usually a step at the intersection frequency, such as

5GHz and 20Ghz. Just like the picture below? Have you ever been in this situation? Do you know how to settle this

Problem?

The return loss of DUT after TRL calibration