Experimental Studies on a Four-Way Microwave Power Combining System Based on Hybrid Injection-Locked 20-kW S-Band Magnetrons

Abstract

A microwave power combining system based on four 20-kW hybrid injection-locked magnetrons in the S-band was proposed and presented. A high-power-capacity power combiner was designed, and the behaviors of the hybrid injection-locking magnetrons were qualitatively explained. An excellent output amplitude stability of 0.01 dB (peak-to-peak), a phase stability of ±0.9° (peak-to-peak), and a spur suppression ratio of -65.0 dBc at 500 kHz were achieved when the injection ratio was 0.07. The proposed four-way 20-kW magnetron coherent power combining system exhibits a total output power of over 60.6 kW and a combining efficiency of 91.5%. Simultaneously, neither real-time automatic phase tuning processes nor high-isolation circulators are required in the system. The results show that a high-efficiency magnetron power combining system has the potential to be applied as a cost-effective high-power microwave source for industrial applications. To the best of the authors' knowledge, a microwave power combining system featuring four 20-kW S-band continuous wave magnetrons has been successfully testified for the first time. The power output of over 60.0 kW and combining efficiency of 91.5% set a new performance record for S-band magnetron power combining systems and represent the best phase noise performance reported for any injection-locked magnetron with an output power of over 15 kW.