Multi-port Vector Network Analyzer Error Model And Calibration Technology Research

The multi-port measurement system has the widespread use in microwave measurement, The measurement of multi-port device with two-port vector network analyzer (VNA) is researched.This paper analyzes the commonly used error models and calibration methods of VNA, program a TRL calibration procedure for two-port VNA, and compare the tested data with the data from VNA. The comparison show that the programmed TRL calibration procedure is in the same accuracy as the VNA.A new design of multi-port test system and its error model is proposed, and the calibration method of measurement system is discussed. In this design, the calibration and the test is done by switching the test channel. In the TRL calibration, for solving the problem that one set calibration kit is not enough for three ports'connection, a new calibration step is added. Based on the principle of multi-port measurement, a three-port measurement system is made. Because in this system there are three switches used to transfer the test channel, a control circuit is made to control the switches automatically, and the control procedure is programmed. Three-port error model is analyzed and the procedure for control, calibration, test and display of this system is programmed.Three-port device with one port terminated with a 50Ohm termination is tested with two-port VNA. The comparison between the VNA test result with the test result of three-port test system show the test system is valid and the test result is accuracy.