Guest Editorial Special Issue on Radar and Microwave Sensor Systems

This Special Issue is devoted to technical papers on radar and sensor systems in microwave and millimeter-wave bands. Massive technological progress has been made in recent years at the microwave device and component level, enabling new research directions on sophisticated microwave and millimeter-wave systems. Among the most significant fields of application for such systems has been sensor technology, with a major emphasis on radar systems. Interest in automotive sensing, wireless human-computer interaction, biometric measurements, industrial monitoring, and target tracking—among many other applications—has driven this interest. Advances in device and component technology are supporting system design concepts that treat the microwave hardware as a co-design element of the system, along with signal processing and antenna design. Such co-design is of particular importance in radar and sensor systems, where a rapidly increasing number of wireless devices and an increasingly crowded spectrum necessitates the design and use of specialized signals (both temporal waveform designs and spatial beamforming) to maintain and improve sensor performance. Systems designed for general broad applicability are becoming more challenging to implement, while specialized systems that co-design the aperture, microwave hardware, and signal processing are becoming increasingly relevant. Technologies such as digital array radar, distributed and networked sensors, computational imagers, high-sensitivity Doppler radars, and integrated millimeter-wave radar, to name only a few, have supported system-level developments.