Single-Layer Dual-Band Polarization-Selective Metafilm With Independently Controlled and Closely Spaced Shielding Bands

Abstract

This article presents a highly compact metafilm structure with two closely spaced and independently controlled shielding bands. The constituent unit cell is a composite of two different single-band metafilm unit cells realized by the application of a meandered-loop resonator and a mu-negative and near-zero (MNNZ) metamaterial liner, respectively, to a metallic disc resonator. Both liners introduce frequency-reduced resonances resulting in highly subwavelength unit cells. The composite dual-band unit cell undergoes resonances at sizes of λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /10 and λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /8 in two operating bands, where it exhibits a fano-shaped reflection profile. The unit cells are closely packed and constructed on a single metallic layer, resulting in a compact and low-profile metafilm design. Furthermore, due to the use of two separate and noninteracting resonance mechanisms, the operating bands are highly selective, can be spaced very close to each other, and may be controlled independently through the design of the individual meandering and MNNZ elements. We present simulation data, extraction of susceptibility tensors using generalized sheet-transition conditions (GSTCs) as well as experiments confirming a dual-band, polarization-selective shielding response using a compact metafilm structure measuring 1.3λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 1.7λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at the lower band and 1.7λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 2.3λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at the upper frequency band. The proposed design remains nearly transparent at other frequencies and/or for the orthogonal polarization.