Microwave impedance measuring scheme using a three-probe microstrip circuit

Abstract

A simple, low-cost three-probe microstrip impedance measuring scheme was developed. The scheme enables easy and prompt determination of the impedance of a device from power measurements at the three probes. A sound theoretical background was derived which fixes some of the drawbacks of previously available methods. Electromagnetic simulations were used to design the hardware and a prototype system was constructed. Disappointingly, experimental results obtained had little correlation with those expected theoretically. However, detailed analysis of hardware imperfections were performed and improvements suggested.