Microwave-Sensing Technology Using Orbital Angular Momentum: Overview of Its Advantages

Industry and academia have agreed that the vortex electromagnetic (EM) wave carrying orbital angular momentum (OAM) provides a dynamic freedom that can enhance radar techniques. For sensing applications in particular, OAM has the potential to improve the performance of conventional object-detection and imaging systems, i.e., OAM-based sensing. To help readers understand this crucial technology, this article offers a comprehensive overview of state-of-the-art OAM-based sensing, including characteristics of the OAM-carrying field, principles of EM vortex imaging and rotational Doppler detection, advantages over conventional systems, and the OAM-generation approach. Several open questions that offer promising ideas to inspire more research in this emerging area are also included. This article presents insights to guide the design and practice of OAMbased sensing systems.