Miniaturized Circularly Polarized Doppler Radar for Human Vital Sign Detection

He, Yuchu; Gu, Changzhan; Ma, Haijiang; Zhu, Jiang; Eleftheriades, George V.

doi:10.1109/tap.2019.2927777

Cited by 45 publications

(21 citation statements)

References 15 publications

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“…As technology evolves, the feasibility of measuring physiological variables using such methods, mixed with the technological advancements in computing hardware, makes research in these area a hot topic. Some examples that can be found in the literature of these methods comprise: continuous wave doppler radar [5], [6], depth-based cameras [7], [8], [9] or even regular consumer-grade cameras [10], [11], [12], [13] to acquire respiration.…”

Section: Introductionmentioning

confidence: 99%

Camera-Based Method for Respiratory Rhythm Extraction From a Lateral Perspective

et al. 2020

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This work proposes a new method based on computer vision algorithms to measure the respiratory rhythm of a subject from a lateral perspective. The proposed algorithm consists on tracking the motion of the intercostal and abdominal muscles by the means of dense optical flow, being the novelty of the proposed method the extraction of the respiratory signal from the phase of the optical flow, while extracting at the same time a quality index from the modulus. 15 healthy subjects were measured while seating, and 4 tests were performed for each subject involving different scenarios. The algorithm has been validated using a commercial wearable thorax inductive plethysmograph system. The instantaneous frequency for the constant frequency respiratory tests, and the breath to breath analysis and instantaneous frequency of the free breathing test have been computed to assess the performance and error of the proposed method for the respiratory acquisition. Finally, a statistical analysis has been performed to assess the accuracy and performance of the quality index. The results of the study show a high agreement between methods in the 0.1 Hz and 0.3 Hz test. For the Free breathing test, both the cycle by cycle and Instantaneous frequency results show a low error between methods with high sensitivity in the cycle detection. The hypothesis that the modulus of the optical flow could be used as a quality index has been corroborated, with very good statistical results. Moreover, due to the simplicity of the proposed algorithm, the proposed method can perform in real-time while measuring respiratory rhythm and assessing the quality of the acquired signal. Further studies taking into account external vibrations have to be performed, to assert that the proposed method can be used in demanding conditions.

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Section: Introductionmentioning

confidence: 99%

Camera-Based Method for Respiratory Rhythm Extraction From a Lateral Perspective

et al. 2020

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“…Since human tissues, such as muscle and skin, are conductive and have high relative permittivity [20], a significant amount of RF energy is reflected and this reflected signal is flipped to the cross polarized handedness to that of the incident wave. This phenomenon has been used in the miniaturization of Doppler radar for monitoring human vital signs, i.e., respiration and heartbeat [4]. In the RFID based human activity detection application, the ''signal'' that correlates to the human activities is not suppressed by the cross polarization configuration as whenever the interaction with human body occurs, the handiness of the reflected CP wave is flipped to the co-polarization configuration to the receiving antenna, so there is no polarization mismatch loss for the ''signal''.…”

Section: Theorymentioning

confidence: 99%

“…Human activity detection is a crucial part in human activity monitoring. Traditionally, camera systems or on-body sensors, such infrared sensors or accelerometer/gyroscopes, and FMCW radar [1]- [4], have been utilized to detect human activity, however, these methods comes with drawbacks [5]- [8]. For video monitoring, extensive amount of computational power is required to process the video received, and cameras have security and privacy concerns…”

Section: Introductionmentioning

confidence: 99%

RFID Based Non-Contact Human Activity Detection Exploiting Cross Polarization

Zhu

et al. 2020

IEEE Access

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This paper explores antenna's polarization for Radio-Frequency Identification (RFID) based non-contact human activity detection. For the first time, a cross circular polarization configuration between reader antenna and tag antenna is proposed to increase the sensing range and spatial sensitivity. Compared to conventional RFID configurations-linearly polarized (LP) tag and circularly polarized (CP) reader, a cross CP configuration can improve the signal-to-noise ratio (SNR) which leads to 230% increase in the detection area over traditional approach in our experiment. As the result of the improvement of spatial sensitivity, the proposed approach can detect subtle and small body movements at almost 4.5m from the reader, such as head movements or even respiration, which enables a low-cost, easy-to-use, non-contact and non-intrusive monitoring of the elderly and disabled peoples in places like hospitals and assisted living homes.

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“…In the open literature, many designs have utilized a branch line coupler as an effective method to achieve dual circular polarization [17][18][19][20][21][22]. The coupler ensures having two output signals equal in magnitude with 90° phase shift needed for CP generation.…”

Section: Introductionmentioning

confidence: 99%

A Compact Dual Circularly Polarized Antenna With Wideband Operation and High Isolation

2020

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This paper presents a dual-sense circularly polarized (CP) antenna with compact size, high isolation, and wideband characteristics. The antenna consists of a microstrip patch, an array of parasitic metal plates positioned around the patch, and a 90° branch line coupler as feeding structure. Unlike the conventional design method, we demonstrate that the wide isolation bandwidth can be achieved with an imperfect coupler and imperfect matching at the radiating element. The final design with overall dimensions of 0.59λ c × 0.59λ c × 0.06λ c (λ c is the free-space wavelength at center operating frequency) was fabricated and tested. Measurements on the fabricated prototype show that the antenna has a bandwidth of 16.5% (5.0-5.9 GHz) with port isolation of better than 15 dB. In addition, a peak broadside gain of about 6.6 dBic is attained. In comparison with other related works in literature, this antenna has advantages of wide operating bandwidth with high isolation while possessing a compact footprint. INDEX TERMSCircular polarization, dual polarization, patch antenna, wideband, high isolation Huy Hung Tran received the B. S. degree in electronics and telecommunications from

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Miniaturized Circularly Polarized Doppler Radar for Human Vital Sign Detection

Cited by 45 publications

References 15 publications

Camera-Based Method for Respiratory Rhythm Extraction From a Lateral Perspective

Camera-Based Method for Respiratory Rhythm Extraction From a Lateral Perspective

RFID Based Non-Contact Human Activity Detection Exploiting Cross Polarization

A Compact Dual Circularly Polarized Antenna With Wideband Operation and High Isolation

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