Design a $\pi$ -Structure-Device Achieve Phase-Locked to $S$ -Band Magnetrons

To increase the power level and simplify the power-combining system, the critical issue is the phase-locked of magnetrons. To solve this problem, a novel structure based on peer-to-peer locking is proposed. The structure called
$\pi$
-structure-device (PSD) consists of a four-port waveguide and two symmetrical metal blocks. Changing the size and relative position of the two metal blocks, scattering parameters can be altered. In simulation, the structure can achieve 99% energy output. To verify this performance, a dual-way magnetron phase-locked system is conducted without extra external signal sources, circulators, and phase shifters. When signals from the magnetrons passed through the structure are injected into each other, the energy will be exchanged ultimately achieving a stable phase difference state, thereby achieving phase locked. Corresponding experimental results indicate that the proposed system can achieve the efficient phase-locked in two magnetrons and the output efficiency is approximately 97.2%. The system has the advantage of high efficiency phase-locked and low cost. An appropriate waveguide structure to form an array can be used to achieve phase-locked of multiple magnetrons. Our investigation is significant for efficient microwave power combining applications.