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Integrated terahertz radar based on leaky-wave coherence tomography


Terahertz wave radar offers a higher resolution and smaller aperture compared with microwave radar. However, despite the emergence of terahertz sources and detectors suitable for radar front ends, the integration of a phased-array radar system remains challenging due to the lack of phase shifters and circulators, the basic components for beam steering and input–output isolation. Here we show that leaky-wave coherence tomography, which can integrate a terahertz radar system using a pair of reverse-connected leaky-wave antennas, can be used to implement beam steering and homodyne detection in one package. Our approach can detect direction and range without using phase shifters, circulators, half-mirrors, lenses or mechanical scanners, providing a compact, penetrating and high-resolution radar system suitable for mobile devices and drones. To illustrate the capabilities of the technique, we use it to create a remote heartbeat detector that can measure the chest displacement of a person through their clothes.

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Fig. 1: Input and output of LWA.
Fig. 2: Structure of the terahertz radar based on leaky-wave coherence tomography.
Fig. 3: Characterization of the device.
Fig. 4: Radar measurement.
Fig. 5: Phase-sensitive measurement.
Fig. 6: Demonstration of human heartbeat detection by phase-sensitive measurement.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author on reasonable request.


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This work was supported by the Strategic Information and Communications R&D Promotion Programme (SCOPE) no. 165103002 from the Ministry of Internal Affairs and Communications. Parts of the work are supported by Japan Science and Technology Agency, PRESTO Grant Number JPMJPR18J9, Japan, and Nanotechnology Platform Japan of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), in Takeda Cleanroom with the help of the Nanofabrication Platform Center of the VLSI Design and Education Center (VDEC), University of Tokyo, Japan.

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H.M. designed the device, performed the experiments and wrote the manuscript. I.W. and A.K. supported the experiments and discussions. Y.M. conceived and coordinated the study, supported the device design and experiments and wrote the manuscript.

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Correspondence to Yasuaki Monnai.

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Supplementary sections, Figs. 1–4 and equations 1–5.

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Matsumoto, H., Watanabe, I., Kasamatsu, A. et al. Integrated terahertz radar based on leaky-wave coherence tomography. Nat Electron 3, 122–129 (2020).

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