Design and Manufacturing of an All-Metal Triple-Bandpass Frequency-Selective Surface Filter Using Laser Cutting Technology

This article presents the design and analysis of an all-metal frequency-selective surface (FSS), aimed at achieving triple-bandpass filtering applications. The proposed structure is manufactured using a laser cutting method on a 1.2-mm-thick stainless-steel sheet. The proposed design is a slot-type element, making it ideal for all-metallic FSS designs. In each unit cell, slots are created by etching complementary split-ring resonator (CSRR) structures. These unit cells are arranged such that adjacent cells are rotated by 90°. The overall <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> configuration of these rotated unit cells forms the final unit cell of the proposed FSS design. The proposed design is polarization-insensitive for both transverse electric (TE) and transverse magnetic (TM) modes. This configuration demonstrated measured resonances at 5.67, 9.04, and 10.47 GHz, with an insertion loss (IL) of less than 1.4 dB across all frequency bands. The overall size of the filter is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.75\lambda _{0} \times 0.75\lambda _{0}$ </tex-math></inline-formula>. The all-metal design offers high robustness and durability, making it an attractive solution for harsh environmental conditions and advanced communication systems.