Orbital Angular Momentum (OAM) Waves for Microwave Remote Sensing: Potentialities and Applications

Electromagnetic vortex waves carrying orbital angular momentum (OAM) have been receiving increasing attention in different domains, from optics to microwave, due to their “phase twists” (helical phase patterns), providing a new rotational degree of freedom, distinct from polarization and useful for wireless information transmission and radar imaging. Microwave remote sensing has produced in the last three decades all-weather, all-time 2-D and 3-D information used for many military and civil applications. OAM-based radar imaging and detection provide new ideas and solutions for improved azimuth resolution images with respect to traditional techniques like Synthetic Aperture Radar (SAR) imaging, based on the range-Doppler technique, for effective detection of a rotational Doppler shift and for deblurring and denoising images of high-speed maneuvering targets. This paper summarizes the main properties and characteristics of vortex waves, investigating the advantages of the new paradigm offered by the OAM observable when applied to radar imaging in the microwave region and illustrating some examples of OAM-based microwave imaging techniques.