Phase control of crossed-field devices for HPM power combining

Summary form only given. There are a number of ways to efficiently injection phase-lock crossed-field devices without the use of ferrites, all of which have been at least partially demonstrated. These include: (1) simple communication of the individual sources via the proper length of interconnecting waveguide, which is simple but which can involve less stability and control as well as lower system efficiency; (2) methods involving four-port reciprocal devices, which appear to have few drawbacks for this application; (3) the various types of cross-field amplifiers; (4) injection circuits on the cathode. which are more complicated but which may allow the best phase control with the least injection power; and (5) prepulse injection locking, where high-Q devices can be injected prior to the output power pulse, potentially allowing isolation of the driver by using a simple switch