Dual-Band Wideband Reflect-Transmit-Array With Different Polarizations Using Three-Layer Elements

A reflect-transmit-array antenna (RTA) with dual-operating modes is proposed in this letter. The proposed RTA, which has a three-layer structure without air layers, can achieve a reflectarray-mode (RAM) at 11-14 GHz and a transmitarray-mode (TAM) at 15-19 GHz. When the incident electromagnetic (EM) wave is y-polarization, the RTA operates at RAM, and the reflected EM wave is y-polarization. In comparison, the RTA operates at TAM and the transmitted EM wave is circular polarization (CP) when the incident EM wave is x-polarization. The dual-mode wideband RTA has been fabricated and measured to validate the design. The measured results indicate that 1 dB bandwidth of 15.7% (11.7-13.7 GHz) can be achieved in RAM and that the maximum aperture efficiency is 63% at 12.4 GHz. Furthermore, 1 dB bandwidth of 17.6% (15.5-18.5 GHz) can be achieved in TAM, and the axial ratio (AR) is less than 2.3 dB within the operating band. Our findings prove a RTA, which can produce different polarizations linear polarization and CP radiation at different modes with a simple architecture without an air layer.