Angle-Selective Surface with Narrow-Angle Filtering for Variable Frequency

The design of this ASS structure is based on a dual-layer frequency-selective surface (FSS), where the unit cell consists of a single substrate and two metal layers. This structure achieves resonant transmission at specific oblique angles while blocking electromagnetic (EM) waves at other angles. In addition, the equivalent circuit model (ECM) is utilized to analyze the proposed structure, revealing the influence of oblique incidenc on circuit parameters. The designed ASS exhibits a transmission performance (S21 ≥ −1 dB) within the range of 18° to 22° at 14.6 GHz and within the range of 28° to 31° at 14.05 GHz.