Triple band microwave metamaterial absorber based on double E-shaped symmetric split ring resonators for EMI shielding and stealth applications

In this paper, a double E-shaped symmetric split ring resonators metamaterial inspired triple band microwave metamaterial absorber (MA) for EMI shielding and stealth applications in C and X band is presented. The proposed absorber comprises double E shaped with two modified split ring resonators-based copper resonators separated by a FR-4 dielectric layer with a thickness of 1.6 mm and back annealed copper with 0.035 mm thickness and an electrical dimension of 0.179λ × 0.179λ, λ is computed at the frequency of 5.376 GHz. The simulated results derived from CST Microwave Studio simulator show that there are three absorption peaks at 5.376, 10.32 and 12.25 GHz with an absorption of 99.9%, 99.9% and 99.7%, respectively. An equivalent circuit model of the absorber is used to study the reflection coefficient characteristics and E-field, H-field and surface current distributions are investigated at absorption peaks in order to understand the electromagnetic wave absorption mechanism. Parametric analyses were also performed to select the appropriate absorption frequencies. In addition, the metamaterial absorber unit cell structure shows nearly perfect absorptions over a wide angle of incidences up to 60° for both TE and TM mode. The proposed MA has a triple band shielding behavior and provides the shielding effectiveness, greater than 40 dB for the entire band for both simulated and measured condition, which is a reasonable reduction in the RF signal to reduce the impact on devices susceptible to electromagnetic interference. The simulated, equivalent circuit model and experimental results for validation purposes showed that the complete results are mutually supportive. The proposed microwave metamaterial absorber is expected to be useful for EMI shielding and stealth applications.