Novel Multifunctional Reconfigurable Wideband Frequency-Selective Filter/Shielding With Independently Controlled Operating Modes

In this article, a novel multifunctional reconfigurable wideband frequency-selective surface is proposed. Compared with the conventional structures that can only realize two switchable states of transmission and reflection, this design could independently manipulate the TE and TM waves through four modes. Second-order equivalent circuits based on two polarizations are studied to solve the impedance mismatch caused by the asymmetric structure and biasing system, by using compensation capacitors. With different biasing voltages, the passband and stopband can be achieved by second-order filter and multireflection responses, respectively. Each mode does not affect the others, while their transmission or reflection performances in the corresponding modes are almost the same. From 0° to 45° incidences, in the transmission state, high-transmittance windows (the minimum insertion loss is 0.1 dB) with a −3 dB fractional bandwidth of 43.2% are realized. When this design operates in the shielding state, it can prevent the incident energy from penetrating the structure with extremely stable oblique incident performances from lower frequencies to 11 GHz. Finally, a prototype is fabricated for measurements, and the proposed design is validated by the calculated, simulated, and measured results.