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Correction published on 31 July 2019, see Electronics 2019, 8(8), 855.

Open AccessArticle

915-MHz Continuous-Wave Doppler Radar Sensor for Detection of Vital Signs

1
Department of Electronic Engineering, Yeungnam University, Gyeongbuk 38541, Korea
2
Department of Robotics Engineering, Yeungnam University, Gyeongbuk 38541, Korea
*
Authors to whom correspondence should be addressed.
Electronics 2019, 8(5), 561; https://doi.org/10.3390/electronics8050561
Received: 26 April 2019 / Revised: 15 May 2019 / Accepted: 17 May 2019 / Published: 20 May 2019
(This article belongs to the Special Issue Radar Sensor for Motion Sensing and Automobile)
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Abstract

A miniaturized continuous-wave Doppler radar sensor operating at 915 MHz to remotely detect both respiration and heart rate (beats per minute) is presented. The proposed radar sensor comprises a front-end module including an implemented complementary metal-oxide semiconductor low-noise amplifier (LNA) and fractal-slot patch antennas, whose area was reduced by 15.2%. The two-stage inverter-based LNA was designed with an interstage capacitor and a feedback resistor to acquire ultrawide bandwidth. Two operating frequencies, 915 MHz and 2.45 GHz, were analyzed with regard to path loss for efficient operation because frequency affects detection sensitivity, reflected signal power from the human body, and measurement distance in a far-field condition. Path-loss calculation based on the simplified layer model indicates that the reflected power of the 915 MHz radar could be higher than that of the 2.45 GHz radar. The implemented radar front-end module excluding the LNA occupies 35 × 55 mm2. Vital signs were obtained via a fast Fourier transform and digital filtering using raw signals. In an experiment with six subjects, the respiration and heart rate obtained at 0.8 m using the proposed radar sensor exhibited mean accuracies of 99.4% and 97.6% with respect to commercialized reference sensors, respectively. View Full-Text
Keywords: heartbeat detection; respiration rate; Doppler radar sensor; path-loss analysis; wideband low-noise amplifier; fractal-slot patch antenna heartbeat detection; respiration rate; Doppler radar sensor; path-loss analysis; wideband low-noise amplifier; fractal-slot patch antenna
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Park, J.-H.; Jeong, Y.-J.; Lee, G.-E.; Oh, J.-T.; Yang, J.-R. 915-MHz Continuous-Wave Doppler Radar Sensor for Detection of Vital Signs. Electronics 2019, 8, 561.

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