Design and Optimization of Aperiodic Bragg Reflector-Inspired Filters with Compact Size for High-Power Applications

The design and optimization of a high-power filter based on the Bragg reflector is presented in this paper. Theoretical analysis of the aperiodic Bragg reflector reveals that, by replacing the periodic cylindrically symmetric corrugations (CSCs) into random ones, required filtering performance may be realized in a designated frequency band. An improved optimization strategy based on covariance matrix adaptation evolution strategy (CMA-ES) is introduced to optimize CSCs for the filter design. Besides, in order to maximize the power capacity and maintain the designed accuracy, the chamfering technique is presented and integrated into the optimization. An optimized geometry, which respectively exhibit the band-pass response with central frequencies of 9.3GHz and ±100MHz bandwidth, is fabricated and measured. Measured results validate the design and optimization with the required operation band, out-of-band suppression ratio and input power handling capability. The experiment results show that HPM beams are successfully operated at 2GW with pulse width of 105 ns.