A Survey of Phase Shifters for Microwave Phased Array Systems

Phased Array Systems (PASs) are extensively used in radar and telecommunication systems for diverse applications, including military surveillance and wireless broadband communication. Besides, they are becoming increasingly indispensable in modern applications such as multi-function phased array radars for weather monitoring and aircraft tracking or high-throughput satellite systems, which aim to provide fast broadband connectivity in remote areas. Despite the numerous advantages of phased array systems with RF phase shift, including high signal-to-noise and signal-to-interference ratios, as well as low complexity, they present a few limitations, including high cost and large chip areas. The cost and size of PASs are mainly dependent on the RF phase shifters, which are essential to their operation. This article describes the different types of phase shifters (mechanical, ferromagnetic/magnetic, electromechanical, and electronic). It compares their performance metrics, highlighting that electronic phase shifters are the most common type used in modern PASs. In this regard, a comparative study of different subcategories of electronic phase shifters, such as the switched-type, reflective-type, loaded-transmission line, and vector-sum phase shifters, are explored along with their advantages, drawbacks and state-of-art techniques used to address their limitations. Therefore, this article may serve as a reference for research milestones on RF phase shifters.