Dual-Polarized Bilayer Angle-Selective Structure

A new concept of 3-D angle-selective structure is proposed in this letter. The 3-D structure has one more longitudinal component than traditional 2-D surfaces, which introduces a new degree of freedom to manipulate the structure's electromagnetic response under different angles of incidence. By stacking two identical layers of this frequency-selective surface with an air gap between them, broadband dual-polarized angular selectivity is achieved. This bi-layer structure shows high transmission under the normal incidence and low transmission under the oblique incidence of large angles. Full-wave simulations show that a passband (|S 21 | > −1 dB) for incident an angle less than 15° and a stopband (|S 21 | < −15 dB) for an incident angle larger than 50° are observed at 10.25 GHz for TE-polarized waves. For TM-polarized waves, a passband (|S 21 | > −1 dB) for an incident angle less than 10° and a stopband (|S 21 | < −15 dB) for an incident angle larger than 40° are obtained. A fabricated ASS sample with 26×26 unit cells is tested and measured results agree well with simulated results.