Four-Layer Dual-Band Metasurface Polarizer Device for Linear-to-Circular Polarization Conversion at Ka-Band SatCom Applications

A method to design a unique dual-band linear to circular transmission polarizer converter is presented in this paper. The polarizer is developed for use in the SatCom Ka-band. It needs to provide two transmission/reception bands with orthogonal polarizations (RHCP/LHCP). It is composed of four identical metasurface sheet separated by quarter-wave thick substrates for easy impedance matching. The susceptances of the metasurface exhibit series resonance for the horizontal linear polarization and parallel resonance for the vertical polarization. The method is based on the dispersion diagrams (phase versus susceptances) and choose the solutions that ensure orthogonally conversion for the two bands. The designed polarizer shows a good frequency behavior with a large bandwidth (up to ~2 GHz for each band), low insertion loss (<0.5 dB), angular stability (up to ± 45°) and axial ratio below 1.5 dB. By twisting the structure by 90°, circular left hand/right hand conversions can be interchanged in the two bands.