Matching Techniques for Microstrip Antennas in Classes Teaching Electromagnetics

This paper describes a procedure for determining the optimal position for a probe-fed microstrip patch antenna to achieve 50 Ohm matching. The procedure requires an initial simulation of the driving point impedance of an arbitrary probe position. Next, the impedance locus as seen on the Smith chart is rotated so that the magnitude of the reflection coefficient lies on the horizontal axis of the Smith chart. After that, one algebraic calculation is used to determine the new probe position needed for a 50 Ohm match. Such techniques give important insight for students learning matching in a classroom environment.