Design of an Absorber for Large Incident Angles with Antenna Reciprocity

In this paper, a novel absorber for large angles of incidence is presented and analyzed using antenna reciprocity. The proposed absorber is a monopole array on a metal ground. According to reciprocity, an antenna array receives signal efficiently when the impinging electromagnetic waves are from the maximum radiation direction i.e., main beam. Since a monopole array with proper excitation shows the maximum radiation at large angles, an absorber for large incident angles could be designed by replacing the feeding port with a matched load. Simulation results show that the proposed absorber achieves an absorptivity of more than 90% from 7.39 to 14.78 GHz under TM polarization with a thickness of 0.0736λ₀ with respect to the wavelength of lower frequency.