Extrema of Two-Port Network Transducer Power Gain and Voltage Gain Under Varying Port Terminations: Semi-Analytical Method and Application to Biotelemetry System

Analysis of the structure of the level sets of transducer power gain and voltage gain of a two-port network enables a semi-analytical method for finding the extrema these performance indicators as the port terminations vary in bounded rectangles in the complex plane. In particular, we show that the extrema are necessarily attained in small-dimensional subsets of the given rectangles. This provides efficient means to assess the impact of variability in the port terminations numerically. As an example, we study how variability in the port terminations affects the performance of a biotelemetry system composed of magnetically coupled small loops with highly sensitive impedance matching properties.