Bidirectional Same-Sense Circularly Polarized Slot Antenna Using Polarization Converting Surface

An asymmetric frequency selective surface (FSS) based on Jerusalem cross-slot (JC-SL) unit cell is used as a polarization converting surface (PCS) to change the sense of the circularly polarized (CP) wave as it passes through it. This is achieved by introducing 0 ^° and 180 ^° phase shifts for the two perpendicular linear polarized components of the CP wave. Without adding any extra phase shift, the transmitted CP wave will encounter a change in its sense of polarization. The PCS is then combined with a bidirectional CP slot antenna to achieve right-hand CP (RHCP) signal on both sides of the antenna. The overall size of the structure is about 0.75λ×0.75λ×0.15λ, where λ is the free-space wavelength. The structure is designed to operate at the GPS L1 band ( f = 1.575 GHz).