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Return Loss of Network Analyzer Ports

Question asked by Leyo on Apr 10, 2008
Latest reply on Apr 14, 2008 by Dr_joel
This is a fundamental question on NW port Return Loss.

1. Consider a two port calibrated  NW. There is a cable on Port1 and another one or port and is taken care during calibration. Now measure S22 with both the cables connect together. Let us say S22 -30dB. This is the impedance looking back at port2 cable or Port2 with cable will present -30dB return loss to any circuit connected to it.

2. Now consider that port2 of this NW is not very good...say 45 ohms instead of 50 ohms and the cable connected to port 2 is 60 ohms cable. What type of S22  measurement I will  get after two port cal and shorthing Port1 and Port2 cable?. I want  to know what is the impedance this port2 plus cale will present to  the circuit when it is connected to the circuit?.