Defected ground structure for bandwidth improvement of artificial magnetic conductor-based microwave absorber

In this paper, the bandwidth improvement technique applied for microwave absorber is numerically investigated. The proposed technique is carried out by defecting or making some structure on the ground surface of microwave absorber, thus it is known as defected ground structure (DGS). The absorber that is constructed based on artificial magnetic conductor (AMC) concept has narrow bandwidth due to the characteristic of AMC structure. There are 3 kinds of DGS pattern utilized in the proposed technique. Each pattern will be investigated and analyzed through the unit cell of AMC structure. From the result, it shows that the bandwidth of microwave absorber with DGS pattern and PEC boundary condition is improved up to 6% compared to the bandwidth of microwave absorber without DGS. The utilization of DGS pattern is also lowering the resonance frequency of microwave absorber from 3.62 GHz to 2.98 GHz for PEC boundary condition. In addition, the incorporation of external resistors with particular resistance value put between adjacent patches in parallel to the incoming wave has shown the significant contribution to increase the absorption rate of microwave absorber.