Power Combining of Dual X-Band Coaxial Magnetrons Based on Peer-to-Peer Locking

Abstract

A system for the power combining of dual ${X}$ -band coaxial magnetrons-based on the peer-to-peer locking is presented in this article. The locking condition of peer-to-peer locking was derived and proposed, in which the frequency pushing effect was taken into account. The frequency pushing parameter of ${X}$ -band coaxial magnetron was measured by an injection locking experiment. Dual ${X}$ -band coaxial magnetrons with similar operation characteristics were employed and driven by single modulator to synchronize the pulse generation in the power combining system based on peer-to-peer locking. As the prediction of theoretical derivation, the locking phenomenon emerged with a locked frequency of 9304.41 MHz when the free running frequency of one magnetron was fixed as 9304 MHz. A combined power of 3.09 MW for 3.5 $\mu \text{s}$ pulsewidth with the total power efficiency of 83.5% was achieved in the experiment, which was approximately 1.5 times the maximum peak output power of commercial ${X}$ -band coaxial magnetron. Due to the measured phase jitter of ±8° caused by the anode current ripple and frequency fluctuation of the magnetrons, the combined power jitter was estimated as ±0.5%, which was acceptable for the system.