The use of terahertz waves for detection and ranging offers a higher resolution and smaller aperture as compared to the microwave radar. However, despite the recently emerging terahertz sources and detectors applicable to radar front-ends, integration of a phased array radar system is still challenging due to the lack of phase shifters and circulators, the basic components for beam steering and input-output isolation. Here we demonstrate leaky-wave coherence tomography, a method to integrate a terahertz radar system using a pair of reversely connected leaky-wave antennas. With this architecture, we implement beam steering and homodyne detection in one package and thereby identify the direction and range toward targets without using phase shifters, circulators, half-mirrors, lenses, or mechanical scanners. Our work paves the way to a high resolution, penetrable, and compact radar system, which is suitable to be equipped even on mobile devices and drones for a wide range of applications. As an example, we demonstrate in-situ human heartbeat detection by measuring the small displacement of the chest of subjects through the clothes, which provides information as with a stethoscope but remotely.
- Hironori Matsumoto, Issei Watanabe, Akifumi Kasamatsu, and Yasuaki Monnai, “Integrated terahertz radar based on leaky-wave coherence tomography,” Nature Electronics (2020). DOIhttps://doi.org/10.1038/s41928-019-0357-4
- Koji Murata, Kosuke Murano, Issei Watanabe, Akifumi Kasamatsu, Toshiyuki Tanaka, Yasuaki Monnai, “See-through Detection and 3D Reconstruction Using Terahertz Leaky-Wave Radar Based on Sparse Signal Processing,” Journal of Infrared, Millimeter, and Terahertz Waves, vol.16, pp.210-221, 2018.
- Kosuke Murano, Issei Watanabe, Akifumi Kasamatsu, Safumi Suzuki, Masahiro Asada, Withawat Withayachumnankul, Toshiyuki Tanaka, and Yasuaki Monnai, “Low-Profile Terahertz Radar Based on Broadband Leaky-Wave Beam Steering ,” IEEE Transactions on Terahertz Science and Technology, vol.7, no.1, pp.60-69, 2017.