3D-printed frequency-selective surface with frequency-switchable and angle-sensitive rejection

Frequency selective surfaces (FSSs) are periodic structures comprising identical two-dimensional (2D) arrays of elements on a dielectric substrate, designed to pass or block electromagnetic waves within specific frequency ranges. Modern high-tech applications demand multifunctional FSSs with advanced capabilities such as multi-band responses or tunable frequency selectivity. Whereas conventional FSSs often prioritize angular stability, angle-sensitive rejection has recently emerged as a valuable feature for selective performance based on the incidence angle. In this study, we propose a novel 3D-printed, kirigami-driven, mechanically deformable FSS with both frequency-switchable and angle-sensitive rejection without the use of any electronic components. By integrating a kirigami-inspired design, the proposed structure achieves mechanical deformability, enabling precise control over its frequency response. The use of strategic cutting and folding techniques facilitates tunable performance across a wide range of frequencies and angles. To implement the 2D-to-2D rotational substrate, we utilized 3D printing technology, offering both material and structural flexibility while maintaining costeffectiveness. Operating in the X-band (8.2-12.4 GHz), the proposed FSS demonstrates distinct functionalities in two configurations: unfolded and folded. In the unfolded state, it exhibits resonant frequencies at 9.15 and 11.73 GHz. Upon folding, a new resonant frequency emerges at 10.81 GHz, which shifts to 10.07 GHz as the incidence angle increases to 40 degrees, following the linear trendy =- 0.0172x + 10.758. These results highlight the FSS's ability to selectively reject frequencies based on both mechanical deformation and incident angle, making it a promising solution for advanced electromagnetic wave management in dynamic environments.