Active Angle Selective Surface for Tunable Angle Transmission Range

In this paper, an angle selective surface (ASS) with a tunable angle transmission range is proposed. The ASS primarily consists of a single metallic layer and an intermediate dielectric substrate, with the metallic layer designed based on the unit structures of annular ring slots and cruciform slots. Four varactor diodes are placed in the curved sections of the annular ring slots. The proposed ASS features characteristics of a bandpass filter with a tunable angle range, where its angular transmission range can be adjusted by changing the parameters of the varactor diodes. The full wave simulation of the ASS demonstrates an angle transmission tunable range from 0° to 80°, tuned at 20° increments. Additionally, when the angle transmission range is $0^{\circ}-80^{\circ}$, the passband ($\mathbf{S 2 1}\gt \mathbf{- 1} \mathrm{dB}$) spans from 0° to 80°. When the angle transmission range is 0°, the passband ($\mathrm{S} 21\gt \mathbf{- 1} \mathrm{dB}$) is at $\mathbf{0}^{\circ}$, and the stopband ($\mathrm{S} 21\lt \mathbf{- 1 0}$ dB) spans from 15° to 80°.