An ultra-thin polarization independent quad-band microwave absorber-based on compact metamaterial structures for EMI/EMC applications

In this paper, a compact metamaterial inspired ultra-thin polarization independent quad-band microwave absorber for electromagnetic interference (EMI)/ electromagnetic compatibility (EMC) applications have been discussed. The proposed absorber structure offers four different absorption peaks having absorptivity of 97.02, 94.07, 91.72, and 98.20% at 3.40, 8.23, 9.89, and 11.80 GHz, respectively. Due to the four-fold symmetry of the designed unit cell, the proposed absorber structure shows polarization independent behavior. In addition to above, the absorption curve for the designed structure has been also analyzed under different angles of incidence for both transverse electric and transverse magnetic polarization states. In order to confirm the metamaterial behavior of the proposed absorber unit cell, dispersion plot has been studied. Further, input impedance plot, electric field, and surface current distribution plot have been discussed to explain the absorption mechanism of the proposed absorber structure. The designed absorber unit cell shows compactness of 0.136 lambda(0) x 0.136 lambda(0) with the ultra-thin thickness of 0.0113 lambda(0), where lambda(0) (free space wavelength) corresponds to the lowest absorption peak of 3.40 GHz. In order to calculate the measured value of absorptivity, the designed absorber structure has been fabricated. Further, it has been observed that simulated and measured results perfectly match with each other. The ultra-thin and compact nature of the proposed absorber structure suggests its potential use in the field of various EMI/EMC applications.