Microwave transmission of free-standing metasurfaces consisting of square metal patch

The transmission characteristics of free-standing metasurfaces consisting of square metal patch, which rotated 45° (which is defined as the rotated metasurfaces) or 0° (which is defined as the regular metasurfaces) around their array arrangement direction, have been studied at microwave frequencies. The proposed metasurfaces in vacuum environment, considered as free-standing planar frequency selective surfaces, are analyzed for searching its transmission characteristics with variable dimension at different frequencies. For the rotated metasurfaces, a bizarre phenomenon, in which transmission will increase inversely as the size of the rotated square metal patch is increased, can be observed at the periodicity of these arrays between 2λ/3 and 4λ/5, where λ is the considered wavelength. But for the regular metasurfaces, this phenomenon cannot be observed. In addition, the rotated metasurfaces and the regular metasurfaces loading on infinite resistive sheet are also studied for discussing its transmission and reflection properties with similar conditions. It is found that the regular metasurfaces loading on infinite resistive sheet show almost linear variable electromagnetic characteristic with the variable size of the regular metasurfaces at a broad frequency range. However, because of the scattering mechanism of evanescent diffraction, the similar linear relationship of electromagnetic characteristic cannot be obtained from the rotated case. These results can be used as a guide for realizing tensor impedance surfaces with various gradient properties.