Improvement in Cross Polarized Performances of Microwave Absorber Using Sequential Metamaterial Inspired Structures

In this paper, an approach for improvement in the cross polarized absorption performances of microwave absorber is presented using the sequential metamaterial inspired structures. Initially the proposed unit cell of the metamaterial structure shows minimum value of cross polarized absorption whereas its copolarized absorption shows minimum 10 dB absorption in the entire X band frequency region. The proposed unit cell of metamaterial inspired structure is based on the hexagonal and circular rings, the hexagonal ring is splitted into two arms. The hexagonal arms that acts as the asymmetric structure is primarily responsible for creating the double resonances, further the co polarized absorption is enhanced due to the presence of inner circular ring. However in this situation the cross polarized absorption is reduced significantly, thus the overall absorption performance of such structure reduces significantly. In order to improve the effective absorber performance of such structure, the same structure is rotated sequentially at an angle of 45° in regular steps and a unit cell of sequential material structure is generated. The proposed unit cell consists of 2 X 4 configuration of metamaterial structure. The proposed configuration of the sequential metamaterial structure shows the significant improvement in the copolarized and cross polarized absorber performances. Further the proposed configuration is validated against the measurement result, it has been observed that the simulated performances are in very close agreement with the measured performances.