Simple Design of a Wideband and Wide-Angle Insensitive Metamaterial Absorber Using Lumped Resistors for X- and Ku-Bands

We report a wideband and polarization-/wide-angle insensitive metamaterial absorber based on a symmetry structure associated with surface mount resistors. The proposed structure consists of a periodic array of a top metal symmetry resonator loading with four lumped resistors and a continuous metal ground plane separated by a dielectric substrate of FR-4. A prototype of the proposed absorber is fabricated and measured, confirming a good agreement between the measurement and simulation results. The proposed absorber shows polarization-insensitive behavior and the absorption response in a frequency range from 8-18 GHz covering the entire X- and Ku- bands with an absorptivity above 80\% for a wide incident angle up to 40^{\circ } for both transverse electric and transverse magnetic polarizations. Compared with the reported broadband absorbers using lumped resistors, our proposed absorber exhibits excellent characteristics in terms of compact and simple structure, high relative absorption bandwidth, and polarization and wide-incident insensitivity. Therefore, this design shows promising potential for both X- and Ku-band applications.