Triple band metamaterial absorber based on right-angle split rings connected by H-shaped capacitive gaps for EMI shielding applications

With electromagnetic interference (EMI) posing a persistent risk to the reliability of compact high-frequency electronics, metamaterial structures offer a promising alternative to traditional shielding methods. This paper aims to develop a triple-band metamaterial absorber (MMA) with multiple resonances for EMI shielding in the C, X, and Ku bands by combining three right-angled split rings connected by H-shaped capacitive gaps. The proposed MMA exhibits six distinct resonance frequencies at 4.12, 5.55, 6.74, 10.496, 12.20, and 17.70 GHz, with corresponding absorption rates of 99.78%, 98.94%, 97.89%, 96.47%, 95.70%, and 98.84%, respectively, at normal incidence up to 180°. At such resonance frequencies, the absorber provides solid protection against EMI, achieving shielding effectiveness (SE) values of 52, 34, 31, 30, 28, and 36 dB, respectively. Additionally, it exhibits an excellent, effective medium ratio (EMR) of 7.3 and a subwavelength unit cell size of 0.138λ × 0.138λ, making it highly suitable for practical EMI shielding applications. An equivalent circuit model is proposed, using surface current distribution analysis, to validate the absorber's simulated results. After fabricating the absorber, data from a vector network analyzer (VNA) were measured to verify the simulated results. A strong correlation is observed between the simulated and experimental results, with both the S 11 response and SE exhibiting practically identical behavior. Because of its performance, it may protect human brain tissues and delicate electronic devices, especially in areas with high electromagnetic field (EMF) exposure.