A Novel Closely Spaced Multiband Complementary Frequency-Selective Surface for Shielding Wireless Communication

Abstract

In this letter, the investigation of a multiorder ultraminiaturized complementary frequency-selective surface (CFSS) suitable for wireless communication is presented. The closely spaced multiorder transmission nulls are formed by integrating the conducting element with its self-complementary aperture elements. The 0.029λ _○ ultraminiaturized frequency-selective surface is developed on the conformal 50-μm-thin polyimide substrate. It operates at 800 MHz, 1.2 GHz, and 1.9 GHz with a wide 10-dB bandwidth of 600, 760, and 620 MHz, respectively. The four narrow transmission zeroes with minimum insertion loss ( S ₁₁ > –2 dB) at 600 MHz, 1 GHz, 1.7 GHz, and 2.7 GHz are achieved at the skirts of three transmission nulls having stronger shielding ( S ₂₁ < –40 dB). The interlayer coupling between the layers exhibits a stable angular response of 75° in transverse electric and transverse magnetic modes. The proposed CFSS maintains its minimal profile size of 0.00032λ _○ with the peak ratio of the closely spaced transmission nulls being 1.5 and 1.58. The equivalent circuit model is studied using the current distribution to analyze its working mechanism. The CFSS is fabricated, and measured results give a correct validation with simulated results. The proposed CFSS is a promising candidate for shielding GPS and global system for mobile communication (GSM) bands.