High aperture efficiency slotted waveguide antenna array for magnetron phase locking system

Abstract We propose a slotted waveguide antenna element for radiating microwaves generated by megawatt-class magnetrons. The conventional end-fed antenna is redesigned into a waveguide-fed structure with the radiating surface parallel to the feed. The feeding port is specifically designed to maximize the compactness of the high-power microwave (HPM) system, achieved by periodically expanding the subarray formed by a magnetron connected to an antenna element through a directional coupler. Grooves are introduced to suppress mutual coupling (MC) between elements and to improve gain as well. The experimental results of the end-fed antenna agree well with the simulations. Moreover, the simulation shows that the change of the feed network has hardly impact on the radiation pattern and gain of the antenna element. An antenna array, consisting of four proposed antenna elements and three grooves, is designed to demonstrate its performance-ultimately achieving MC below −23.3 dB and a gain of 25.8 dBi, corresponding to an aperture efficiency (AE) of 88.6% in simulation. The grooves also enhance gain by 2.91 dB, presenting strong potential for developing high-AE antenna arrays for magnetron-based HPM radiation systems.