A New Technique for Microwave Circuit Parameter Measurement

At present two basic techniques are used for automatic microwave circuit parameter measurements. Automatic network analyzers (ANA) based on vector voltmeter are well-known. Their great advantage is exqremely high accuracy of measurements. But from the other hand they are rather expensive because of the several reasons. Before coming to complex ratio meter the ANA´S signals proportional to incident and reflected wave magnitudes are passed through the analog signal processing unit containing the complex and expensive circuits of automatic gain control, phase lock loop, phase detectors, etc. Besides, the large kit of precise calibration standards is required at every measurement frequency to make up the imperfect responses of directional couplers extracting incident and reflected waves. The use of couplers with high direction (> 40 dB) can diminish considerably this source of errors but leads to rise in cost of the whole ANA. Therefore, it will be a good idea to eliminate the unit of analog processing including the complex ratio meter entrusting its functions to computer which can take account of imperfect performance of directional couplers.