CIRCULARLY POLARIZED YAGI-UDA-LIKE TRANSMITARRAY

A novel Yagi-Uda-like transmitarray is proposed for circularly polarized (CP) operation. The element consists of multiple strips stacked in parallel for achieving broad transmission phase range. By employing the design concept for the Yagi-Uda director, the transmitarray elements are made to provide the functions of phase shifter and director simultaneously. By introducing rotational offset into the stacking strips, the element is found to be able to generate circular polarization. To demonstrate the working principle, an 8-layer unit element is simulated using the Floquet method to provide a transmission phase range of 412◦. The proposed 5× 5 full-fledged CP transmitarray is able to produce an antenna gain of 16.2 dBi, a −1-dB bandwidth of 4%, an axial-ratio bandwidth of 7%, and an aperture efficiency of 40.4%. A simple curve-fitted design equation is also given.