Hexagonal-shaped frequency selective surface based cross-polarization converter for ultra-wide and narrow band applications

• A slotted hexagonal-shapedresonator-based frequency selective surface on an FR4 substrate as a cross-polarisation converter is designed and investigated. • The designed structure exhibits dual-band characteristics with an efficiency greater than 99 %. The band with a width of 3 % and 34 % can be used for both narrow and wide band applications. • The metasurface has a good bandwidth for broadband applications. Moreover, the proposed surface is insensitive to the input incident angle till 15 GHz frequency. Hence, it can manipulate the polarisation of the input signal incident at any angle. • The theoretical analysis of the proposed structure is modelled using transmission line concepts. The Z parameters of the proposed structure are derived using this concept and converted into reflection coefficients. The manuscript portrays the design and analysis of the polarisation converter using frequency-selective surfaces in the 5 GHz to 11 GHz band. The designed structure exhibits narrow and wide bands with the co-polarised reflection levels below -10 dB for the wide range of the incident angle of the input. Additionally, the cross-polarised response of the structure is stable over a wide range of incidence angles in the case of x- and y-polarised input signals. Moreover, the structure exhibits three resonance modes at 5.5 GHz, 8.4 GHz and 10.5 GHz, with the passband varying from 5 GHz to 11 GHz. It is observed that the conversion efficiency of the proposed frequency-selective surface-based polarisation converter is greater than 99 % in the passband. Furthermore, theoretical analysis of the dual-band metasurface is proposed and is validated using the finite element method.