Wideband High‐Angle Stability Active Frequency Selective Surface Applied to the C‐Band

ABSTRACT

Spectrum congestion and a more complex electromagnetic environment have made electromagnetic interference (EMI) increasingly severe, bringing unprecedented challenges to electromagnetic compatibility (EMC). This study proposes a tunable frequency selective surface operating around 5 GHz, featuring a 4.6 GHz passband and high‐angle stability. By integrating PIN diodes, the structure can switch among four modes and enable polarization‐independent control for TE and TM waves. It provides a new design route for achieving wide bandwidth with a single‐layer configuration. The −0.5 dB passband bandwidth exceeds 26%, and the minimum insertion loss is only 0.11 dB. The proposed surface exhibits a bandpass response from 3.4 GHz to 8 GHz, offering a 92% −3 dB fractional bandwidth and covering the entire C band. Its angular stability remains up to 60°. A prototype array was fabricated and tested in a microwave anechoic chamber.