Bandwidth comparison of rectangular and offset cross‐slot frequency‐selective surface polarisation transformers

This letter compares the 3 dB axial ratio (AR) bandwidth (BW) of transmission mode single‐screen linear‐to‐circular polarisation convertors based on three different slot topologies. Using a conventional centre‐connected cross‐slot arrangement as a baseline, we show that a significant performance improvement can be achieved by creating a more elaborate design with unit cells composed of multiple unequal length offset rectangular‐shaped apertures. The additional flexibility to tailor the shape of the Transverse Electric (TE) and Transverse Magnetic (TM) spectral amplitude and phase responses is exploited to achieve an 84% increase in the BW relative to the baseline for a freestanding structure, which is designed to work at a centre frequency of 10.0 GHz. Experimental AR results are used to verify the new design methodology.