A polarization insensitive metamaterial inspired absorber with a transparent window using complementary structure for EMI/EMC applications

This paper presents a metamaterial inspired absorber using complementary design with an absorption band and a pass window at the 9.7 GHz and 4.09 GHz respectively. The substrate chosen for the proposed design is a low cost FR-4 dielectric material with dielectric constant of 4.4 and loss tangent 0.02 and the substrate height is 2 mm. The unit cell of the proposed absorber comprises of modified cross dipole metallic patch and a complementary cross dipole slot in the back plane. Two substrate layers with copper clad at one side and each having thickness of 1 mm is used. The low profile polarization insensitive behavior makes it valuable for EMI reduction at 9.7 GHz, while remains transparent at the 4.07 GHz frequency band and for rest of the band it remains reflective. The surface current distribution and power loss density at the upper and lower planes are also analyzed to elaborate the absorption and transmission mechanism of the structure.