Application of thin dual-band electromagnetic absorbers to reduce the radar cross section of a microstrip patch antenna

In this paper, a thin microwave electromagnetic absorber based on a high-impedance surface is proposed in order to serve as a ground plane for a square patch ISM microstrip antenna. While the bottom layer is fully grounded, preventing any transmission of waves, the top layer is made of periodic, metallic double square rings that reflect waves within the two antenna working bands. Simulations yield scattering parameters, which are then used to obtain the absorptivity, permittivity and permeability of the absorbing structure. In the best scenario tested, the absorber is capable of reducing the radar cross section of the antenna by more than 10 dB in both its bands, namely 12.3 dB at 2.45 GHz and 16.2 dB at 5.65 GHz.