Compact Frequency-Reconfigurable Waveguide Filter by Loading AMC Structures

This paper presents a novel frequency-reconfigurable filter employing two waveguide resonators integrated with mushroom-type artificial magnetic conductor (AMC) structures and metallic tuning elements. By exploiting the AMC's inherent property of functioning as a perfect magnetic conductor (PMC) at resonance, the required boundary conditions for half-mode waveguide resonator design are obtained, enabling significant miniaturization. The proposed filter realizes continuous frequency tuning through linear movement of the tuning element while maintaining constant absolute bandwidth over the tuning range. Simulated results demonstrate excellent performance, including a continuous tuning range from 29.68 to 30.46 GHz, consistent insertion loss below 1.5 dB, and high out-of-band rejection, validating the effectiveness of the proposed design for reconfigurable filtering applications.