Design of 2-Bit Circularly Polarized Reflectarray for Broadband Vehicle Communications

Abstract

As an indispensable supplement to the terrestrial Internet of Vehicles (IoV), satellites provide a promising alternative for broad IoV coverage. To improve the broadband connection in satellite IoV service, this paper presents a novel broadband 2-bit circularly polarized (CP) reflectarray (RA). By analyzing the phasing characteristic of dual-loop unit cell, a -180° phase difference is achieved through a novel method of arranging resonances of the single loop and dual-loop. Owing to the wider phasing bandwidth of the dual-loop unit cell, -90° and -270° phase delays are obtained by changing the parameters of the dual-loop unit cell. The phase bandwidth of 70.5° ≤ | φ| ≤ 109.5° is first-time introduced to characterize the AR bandwidth for the developed 2-bit unit cells. Therefore, compared to the traditional method focusing solely on the scaled size for reflective phase response, broadband AR and gain performances are obtained. Finally, as a performance demonstration, a planar RA composed of the developed 2-bit unit cells was fabricated and measured. Measured results confirm that broad 3dB gain bandwidth of 32% and 3dB AR bandwidth of 53% are achieved with high gain radiation, which show a good candidate for low-cost broadband and wide area coverage for satellite loV service.