Single-Layered Frequency Selective Surface for Polarization Processing by Transmission Through Elementary Simple Structure Unit Cell Array

A single metal layer, multifunctional frequency selective surface with a very simple pattern of the unit cell, containing a U-shaped metal resonator on FR4 substrate, and working in the low GHz frequency range is proposed. The structure realizes dual linear polarization filtering at frequencies of 1.83 and 4.14 GHz with fractional bandwidths of 34.15% and 22.51% respectively, and linear-to-circular polarization conversion at 2.68 GHz, with 3.2 dB insertion loss (IL), 30-45° angular stability depending on the direction of arrival of the incident wave, and 22.01% axial ratio bandwidth. The dimension of the unit cell corresponds to 0.09, 0.13 and 0.21 fractions of wavelength at the three operational frequencies. The functionality of the proposed structure is assessed by simulation, circuital model, and experiment in anechoic chamber. Scalability is demonstrated by designs that work at different frequencies, tested by simulation.