A 3-D Wide Passband Frequency Selective Surface With Sharp Roll-Off Sidebands and Angular Stability

In this letter, a three-dimensional (3-D) wide passband frequency selective surface (FSS) is proposed. Compared with planar wide passband FSSs, 3-D structures usually present superior roll-off characteristics, especially under a lower frequency. However, 3-D wideband FSSs typically have greater insertion loss in the passband, and the transmission characteristic is sensitive to the angle of incident electromagnetic wave. The proposed FSS, by concurrently applying the design methods of planar FSSs and 3-D FSSs, provides sharp double roll-off sidebands while maintaining excellent angular stability and low insertion loss in a wide passband. The simulation results show that the designed FSS can achieve a passband range from 5.86 to 13.4 GHz with an insertion loss of less than 1 dB, and it can retain a stable transmission characteristic with the incident angle ranging from 0° to 45°. The proposed FSS is fabricated and measured in an anechoic chamber, and the measured results show that the fabricated FSS achieves a −3 dB passband from 5.33 to 14.5 GHz. Under different incident angles ranging from 0° to 45°, the FSS also features the lower and upper roll-off transition bandwidths of 6.4% and 4.7%, respectively.