The absorption bandwidth of a metasurface absorber can be adjusted by varying the thickness of the substrate, shape of the conductive pattern attached on top of the substrate, or conductivity of the pattern. In this study, the bandwidth of a pixelated metallic metasurface absorber was analyzed with respect to its unit cell size. The genetic algorithm (GA) was used to determine the best combination of the metallic pixels among 16 × 16 square pixels for each unit cell size. The size of the unit cell was adjusted around the 1/2 wavelength, which guarantees the suppression of the grating lobe for the normal-incidence condition. Based on full-wave simulation results, the -10 dB reflectance bandwidth was expanded as the size of the unit cell was increased from 3/8 to 3/4 wavelength with an interval of 1/8 wavelength at the center frequency of 5.8 GHz. The results demonstrate that the absorption bandwidth of the metasurface absorber is expanded by increasing the size of the unit cell around the 1/2 wavelength.

In this letter, a design and an experimental verification of a face-to-faceantennas system combined with a metasurface absorber are presented, from which interference and cross talk are eliminated. First, the metasurface absorber unit cell composed of square copper pixels is optimally designed with the far-field-incidence condition utilizing the genetic algorithm to satisfy the −10 dB reflectance from 5.75 to 5.83 GHz with the minimum reflectance −13.90 dB at 5.8 GHz. Then, the metasurface absorber is integrated into a pair of 2 × 1 array antennas, of which the resonance frequency is 5.8 GHz. The two array antennas are set to face each other to enable short-distance wireless-data transmission between two antennas aligned in a line of sight. By absorbing undesired reflected waves using the metasurface absorber, interference induced on the transmitted spectrum along the vertical direction and cross talk along the horizontal and diagonal directions can be eliminated at the same time. They are confirmed by the simulation results calculated for various distances between the pair of array antennas. The measurements are well matched to the simulations, verifying the accuracy of the proposed design.