Design of Angle-Selective Surface With Narrow-Angle Filtering for Variable Frequency

This letter proposes a design of angle-selective surface (ASS) with narrow-angle filtering for variable frequency. The proposed ASS structure is based on a dual-layer frequency-selective surface, where the unit cell comprises a single substrate and two metallic layers. This configuration enables resonant transmission at specific oblique angles while effectively blocking electromagnetic waves at other angles. Furthermore, an equivalent circuit model is employed to analyze the proposed structure, revealing the influence of oblique incidence on circuit parameters. The designed ASS demonstrates excellent transmission performance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${S_{21}} \geq -1 \text{ dB}$</tex-math></inline-formula>) within the angular ranges of 18<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> to 22<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> at 14.6 GHz and 28<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> to 31<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> at 14.05 GHz. To verify the effectiveness of the proposed design, a prototype was fabricated and measured, with the measured results exhibiting great consistency with the simulation results.