High-Efficiency Isolator-Free Magnetron Power Combining Method Based on H-Plane Tee Coupling and Peer-to-Peer Locking

TL;DR

This paper introduces a novel, isolator-free magnetron power combining method using H-plane tee coupling and peer-to-peer locking, achieving high efficiency and power output with reduced system complexity and cost.

Contribution

The paper presents a new peer-to-peer injection locking technique for magnetrons that eliminates the need for isolators, reducing size and loss while maintaining high power combining efficiency.

Findings

Achieved up to 93.6% power combining efficiency.

Generated output powers exceeding 1.6 kW without isolators.

Experimental results closely match numerical simulations.

Abstract

Magnetrons are widely used as high-performance microwave sources in microwave heating, microwave chemistry, and microwave power transmission due to their high efficiency, low cost, and compact size advantages. However, the output power of a single magnetron is limited by its resonant cavities, posing a physical constraint. High-efficiency coherent power combining based on the injection-locking technique effectively overcomes this limitation and meets the demand for higher output power. Nevertheless, using isolators, such as circulators, introduces significant insertion loss, and the injection signal sources and phase shifters increase the system size, cost, and complexity in a conventional magnetron power combining (MPC) system. A novel method is proposed to utilize the coupling between two ports of an H-plane tee to achieve peer-to-peer injection locking magnetrons. Meanwhile, an asymmetric phase compensation is realized using a section of waveguide to adjust the magnetron output characteristics. Theoretical and numerical analyses provided qualitative insight into the system output behavior. Subsequently, an experimental system was developed for verification. In the experiments, the system achieved maximum microwave power combining efficiencies 90.2%, 93.6%, and 93.6% at electrical waveguide lengths corresponding to 90, 135, and 225, with output powers of 1650, 1260, and 1610 W, respectively, without the use of any isolators or external injection sources. The experimental results show good agreement with numerical calculations. This method offers the advantages of low cost, compact size, and low loss, providing a new approach for developing high-performance MPC systems in the future.