Development of coding based metasurface absorber for radar cross section reduction and electromagnetic interference shielding

Abstract

Radar cross section (RCS) reduction and electromagnetic interference (EMI) shielding are crucial for enhancing the stealth and electromagnetic compatibility of various systems, including military platforms, by minimizing radar detection and mitigating electromagnetic interference. Coding-based metasurface absorbers (CMA) show promise in RCS reduction and EMI shielding applications, countering the limitations faced by conventional metasurface absorbers in achieving significant reductions due to inherent design constraints. This research aims to develop a coding technique to enhance the capabilities of metasurface absorbers in achieving high RCS reduction and shielding effectiveness. The simulation process extensively employed Computer Simulation Technology (CST) Microwave Studio, a high-frequency electromagnetic simulator based on the Finite Integration Technique. The coding element comprises of a triple circular ring resonator designed on Flame Retardant 4 substrate which generates 1-bit coding scheme (‘0’ and ‘1’ element) with a reflection phase difference of 1800 , and 2-bit coding utilizes four elements (‘00’, ‘01’, ‘10’, and ‘11’) with a phase difference of 900

, respectively. Binary Particle Swarm Optimization (BPSO) algorithm with array theory is applied to choose the best location for unit cells in the subarray in order to achieve high shielding effectiveness and RCS reduction. For this reason, the better results were obtained from this research. Firstly, three novel conventional metasurface absorbers, including one with a double E shape, another with double elliptical-based resonators and a third with triple circular rings, were designed and analysed for the dual purposes of reducing RCS and offering EMI shielding. Secondly, a 1-bit CMA were effectively designed and analysed for RCS reduction and EMI shielding applications. The CMA demonstrates excellent capabilities, including an absorption levels exceeding 80% at different resonance frequency within the frequency range of 9.04 GHz to 14.7 GHz, strong shielding effectiveness, and a significant reduction of -10 dBsm in RCS between 7.5 GHz and 15.5 GHz. Finally, 2-bit CMA pattern using same unit cell design as 1-bit utilizing the variable dimension of outer circular ring reveal promising results. Simulation results show that the optimized 2-bit CMA pattern presents -10 dBsm RCS reduction across a wide frequency band of 7.5 to 17.5 GHz. The CMA pattern demonstrates high shielding effectiveness by maintaining near unity absorption performance regardless of polarization and incident angle insensitiveness. The findings indicate that 2-bit CMA pattern provides greater flexibility compared to the 1-bit pattern, for instance, the 2D and 3D scattering pattern of 2-bit CMA at 11.9 GHz demonstrate superior results compared to the 1- bit CMA. Additionally, the monostatic RCS and absorption results also indicate better performance with the 2-bit CMA compared to the 1-bit CMA. Finally, the effectiveness of the CMA pattern was verified through experimental investigation to evaluate its capability in absorption performance and shielding against EMI. Coding based metasurface absorbers have a significant potential for applications involving RCS reduction and the EMI shielding because they have the ability to manipulate electromagnetic waves to achieve various functionalities.