Coherent power combining of four-way injection-locked 5.8-GHz magnetrons based on a five-port hybrid waveguide combiner

TL;DR

This paper demonstrates a highly efficient method for coherently combining four 5.8-GHz magnetrons using a five-port hybrid waveguide, achieving over 95% power combining efficiency with minimal phase fluctuation.

Contribution

It introduces a novel power combining system using injection-locking and a five-port hybrid waveguide, achieving high efficiency without phase-locked loops.

Findings

Over 95% power combining efficiency achieved

Phase fluctuation reduced to 0.5 degrees with phase-locked loop

Minor impact of magnetron phase-pushing and ripple effects on efficiency

Abstract

A high-efficiency power-combining method for four-way 5.8-GHz magnetrons based on the external injection-locking technique is presented in this article. The method uses a nonisolated, lossless five-port hybrid waveguide combiner for power combining. Meanwhile, the injection-locking technology has been applied to magnetrons for achieving coherent power combining. The phase fluctuation of the injection-locked magnetron, without the presence of a phase-locked loop, measured nearly 2.5 degree. In contrast, when a phase-locked loop was introduced, the phase fluctuation reduced significantly to approximately 0.5 degree. This phase accuracy can fully meet the requirements of combining experiments. Four magnetrons worked in injection-locked states without phase-locked loop. The proposed power-combining system is designed, measured, and analyzed. Measurement results show that a high-power-combining efficiency of over 95% is achieved by injection-locked magnetron without PLL, with the best efficiency reaching up to 97.7% with phase control of the injected signals. Experimental results reveal that the magnetron phase-pushing effects and the ripple in high-power dc voltage and current have a minor impact of approximately 4% on the combining efficiency.