A Low-Profile Broadband Dual-Beam Folded Transmitarray Antenna

A novel folded transmitarray (FTA) integrating anomalous reflection and spin-decoupled methods is proposed to simultaneously realize arbitrary low profile and independent dual-circularly polarized (CP) beam control. The FTA consists of a transmissive metasurface (TMS), a polarization conversion metasurface (PCMS), and a feeding source. The spin-decoupled method is employed to control the phase of the TMS, enabling independent manipulation of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) beams. Additionally, anomalous reflection is implemented in the PCMS to alter the propagation path of electromagnetic (EM) wave, allowing the single-reflection FTA to achieve a similar low-profile characteristic comparable to that of multi-reflection designs. For demonstration, two FTA prototypes with dimensions of 180 mm W 180 mm are designed and experimentally characterized. Experimental results illustrate that both of them effectively reduce the profile of conventional transmitarray to 1/3 and 1/4. Moreover, the FTA in the former case exhibits a 3 dB gain bandwidth of 23.1% for the LCP beam and 23.1% for the RCP beam. In the latter case, a 3 dB gain bandwidth of 23.1% and 23% is achieved for dual beams. Our proposed strategy provides promising applications in circularly polarized communication systems requiring broadband operation, high integration, and low-profile characteristics.