Multifunction Metasurface Structure for Absorption and Polarization Conversion Application

A multi-functional metasurface structure is presented in this paper. This metasurface consists of two resonating structures printed on two FR-4 substrates, while the bottom side of the structure is completely laminated with copper. The proposed design offered absorption at 6.1 GHz frequency with 200 MHz bandwidth and polarization conversion in the X band from 7.8 to 11.9 GHz frequency band. The presented unit cell is compact with a length and width of $0.31\lambda\times 0.31\lambda$ while thickness is $0.081\lambda$, where $\lambda$ is the free-space wavelength at 6.1 GHz. The simulation results show that the proposed structure absorbs EM wave at 6.1 GHz in the C band with angular stability of up to 70° for both TE and TM polarization. Whereas the four-fold symmetry inside the resonator provides polarization insensitivity in nature. Along with this absorption phenomenon, this proposed structure also provides a polarization conversion phenomenon in the X band from 7.8 −11.9 GHz with angular stability of up to 50°. The absorbance mechanism in the proposed structure is further explicated with the help of surface current distribution, E-field distribution, and impedance plot, whereas the polarization conversion mechanism has been explained with the help of reflection due to cross-polarization.