Rotational symmetric metamaterial structure of emblemed number connected with continuous transmission line for EM wave shielding applications

Abstract

Electromagnetic (EM) wave shielding in modern wireless systems encounters critical challenges, including polarization insensitivity, broadband operation, and compact design requirements. This work introduces a rotationally symmetric metamaterial absorber featuring emblem-shaped continuous transmission line resonators, specifically engineered to achieve high-efficiency absorption across the C, X, and Ku bands. The proposed design demonstrates remarkable absorption rates of 96.77 %, 99.68 %, 99.68 %, 99.70 %, 98.03 %, 99.68 %, and 99.98 % at resonance frequencies of 5.834 GHz, 7.192 GHz, 7.766 GHz, 10.65 GHz, 14.038 GHz, 15.34 GHz, and 15.62 GHz, respectively. Benefiting from rotational symmetry, the absorber maintains complete insensitivity to both co- and cross-polarized incident waves, with stable performance under oblique angles up to 90°. A maximum shielding effectiveness of 78 dB is achieved at the targeted frequencies, ensuring robust protection against EM interference. The compact unit cell (0.233λ × 0.233λ) exhibits near-zero permittivity, permeability, and refractive index with single-negative properties, further supporting efficient absorption within a minimal footprint. To validate the physical behavior, an equivalent RLC circuit model was developed in ADS, showing excellent agreement with CST simulations. Experimental verification using fabricated prototypes and Vector Network Analyzer measurements confirms the strong consistency between simulated and measured results. The novelty of this work lies in the integration of an emblem-shaped resonator with a continuous transmission line in a rotationally symmetric layout, enabling broadband absorption, polarization, and angle insensitivity, as well as high shielding effectiveness within a compact geometry. These features make the proposed absorber highly suitable for Wi-Fi, 5G, aerospace, defense radar, and stealth EM shielding applications.