Antiparallel operation of multiple high-efficiency avalanche diodes

This paper describes a new method for combining RF power from multiple high efficiency avalanche diodes. The basic circuit, called an antiparallel pair, has two avalanche diodes placed in opposite polarity to each other at the ends of an essentially one-half wavelength transmission line. A high-efficiency avalanche diode receives an incident half-sine wave and reflects an amplified half sine wave of opposite polarity. The half-sine wave travels back and forth along the transmission line with its polarity being reversed at each of the two diode positions. The antiparallel configuration has been extended to a circuit that combines RF power from four diodes. The four diodes are placed at the ends of a K-shaped microstrip line with two of the diodes being placed in opposite polarity with respect to the other two. The distance between any two diodes is approximately one-half wavelength. The K-shaped circuit has generated 620 W at 1.02 GHz.