A Wideband 2-Bit Transmitarray Antenna for Millimeter-Wave Vehicular Communication

A wideband transmitarray antenna based on the magnetoelectric (ME) dipole element and 2-bit phase compensation scheme is presented for vehicular communications in this paper. A wideband 90° phase shifter is proposed and combined with the rotating method to achieve four discrete phase states. Thanks to the polarization-twisting technique and the simple structure of the phase shifter, the proposed element can be easily designed. For the transmitarray design, a multi-frequency phase compensation strategy is applied to guarantee stable performance over the operating band. To validate the design, a 12 × 12 transmitarray antenna simultaneously covering vehicle-to-satellite band (20 GHz), and 5G millimeter-wave (mmWave) bands (24 GHz/28 GHz) is designed, fabricated and measured. The experimental results show that the prototype can achieve high aperture efficiencies (>40%) within a wide bandwidth (34%). The measured peak aperture efficiency is up to 53% at 23 GHz. These results demonstrate that the proposed 2-bit transmitarray antenna enjoys the advantages of wide operating bandwidth, high aperture efficiency and comparatively low design complexity. With these characteristics, the proposed transmitarray antenna can be a promising candidate for vehicular communications that require reliable satellite links and 5G millimeter-wave connections simultaneously.