A Wide Band Square Loop Circuit Analog Absorber with Low Periodicity

The absorber consisting of two FR4 dielectric substrates separated by air is presented. A square loop shaped frequency selective surface loaded with lumped resistors is used on the top substrate where as the bottom substrate uses a ground plane. The impedance analysis technique of equivalent circuit of the absorber is used to obtain design guidelines. The proposed absorber has a low profile of 0.776 wavelengths at the lowest operating frequency. The absorption bandwidth of 99.27 percent is achieved. Full wave simulation results show stable performance up to 50 degrees angle of incidence and polarization insensitivity.