Linear to Circular FSS Transformer for Dual-Polarized Applications

This paper presents a Frequency Selective Surface (FSS) placed in front of an array of circular apertures. The FSS is aimed at reducing the grating lobes of the apertures' radiation pattern, and transforming the linearly-polarized pattern of the apertures into a circularly-polarized pattern. To do so, the FSS incorporates 45° stubs capable of exciting two orthogonal modes with a 90° phase shift. Results show an axial ratio below 1 dB at the central frequency, and a reduction of 16.46 dB in the grating lobes level. The symmetric configuration of the FSS allows a dual-polarized (LHCP/RHCP) operation in a single structure by just feeding the aperture with an appropriate linear mode (V/H).