Band Doppler Radar Research Articles

Doppler Cardiogram Detected by a V-Band Doppler Radar Sensor

Capable of remote presentations of human heart activities, the Doppler cardiogram (DCG) can be detected by an agile Doppler radar sensor. However, as a recently developed technology, its performance needs sustained improvements for the future practical applications. In this work, a continuous-wave, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> -band Doppler radar sensor was implemented to improve the discrimination of the receiver, for detecting micrometer-level details of heartbeat motions conducted to the chest skin. Besides, new algorithms were derived to achieve high linearity, to demodulate the Doppler phases and retrieve the fine details of DCG waveforms. Experimental measurements to different subjects showed significantly enhanced robustness and accuracy. The obtained results imply a promising potential of DCGs in wide application scenarios such as medical wisdom and personal healthcare.

Numerical Study on the Feasibility of a 24 GHz ISM-Band Doppler Radar Antenna for Near-Field Sensing of Human Respiration in Electromagnetic Aspects

The feasibility study of a 24 GHz industrial, scientific, and medical (ISM) band Doppler radar antenna in electromagnetic aspects is numerically performed for near-field sensing of human respiration. The Doppler radar antenna consists of a transmitting (Tx) antenna and a receiving (Rx) antenna close to the human body for a wearable device. The designed slot-type Doppler radar antenna is embedded between an RO4350B superstrate and an FR-4 substrate. To obtain the higher radiation pattern of the antenna towards the human body, a ground plane reflector is placed underneath the substrate. The measured −10 dB reflection coefficient (S11) bandwidth is 23.74 to 25.56 GHz and the mutual coupling (S21) between Tx and Rx antennas is lower than −30 dB at target frequencies. The Doppler radar performance of the proposed Doppler radar antenna is performed numerically by investigating the signal returned from the human body. The Doppler effect due to human respiration is investigated through the I/Q and arctangent demodulation of the returned signal. According to the results, the phase variation of the returned signal is proportional to the displacement of the body surface, which is about 0.8 rad in accordance with 1 mm displacement. The numerical experiments indicate that the proposed Doppler radar antenna can be used for near-field sensing of human respiration in electromagnetic aspects.

ICA for Separation of Cardiac and Respiration Signals Measured from 10 and 24GHz Band Doppler Radar

ICA for Separation of Cardiac and Respiration Signals Measured from 10 and 24GHz Band Doppler Radar

A 24 GHz ISM-Band Doppler Radar Antenna With High Isolation Characteristic for Moving Target Sensing Applications

A 24 GHz Industrial, Scientific, and Medical (ISM)-band Doppler radar antenna with high isolation is proposed for moving target sensing applications. Both transmit (Tx) and receive (Rx) antennas consist of 2 × 2 microstrip patch antenna arrays. High isolation of the proposed antenna is achieved by inserting periodic Jerusalem cross slot array between Tx port and Rx port, and thus the surface wave from Tx port to Rx port is significantly suppressed. The −10 dB reflection coefficient bandwidth of the proposed antenna is 510 MHz, and the isolation between Tx port and Rx port is higher than 36.7 dB over the 24 GHz ISM band. The simulated half-power beamwidths are 58.53° for E -plane and 47.54° for H -plane. Experimental results show that high isolation can lead to improve Doppler radar performance. The proposed antenna can be a good candidate for contact-free monitoring of the heart rate and respiration rate in healthcare applications.

Frequency selective surface antenna for remote vital sign monitoring with ultra-wide band doppler radar

A high gain frequency selective surface (FSS) antenna is proposed for noncontact remote vital signs monitoring (RVSM) with low power (−10 dBm) Doppler radar at 9.9 GHz frequency. High antenna gain (18.25 dBi) and narrow beam-width enhanced the accuracy of human breathing rate (BR) and heart beat rate (HR) detection from remote distance in the range of 5 cm to 1 m. Two antennas have been fabricated and tested for which the measured and simulation results showed good agreement. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:818–823, 2017

Estimation of physiological sub-millimeter displacement with CW Doppler radar.

Doppler radar physiological sensing has been studied for non-contact detection of vital signs including respiratory and heartbeat rates. This paper presents the first micrometer resolution Wi-Fi band Doppler radar for sub-millimeter physiological displacement measurement. A continuous-wave Doppler radar working at 2.4GHz is used for the measurement. It is intended for estimating small displacements on the body surface resulting from physiological activity. A mechanical mover was used as target, and programmed to conduct sinusoidal motions to simulate pulse motions. Measured displacements were compared with a reference system, which indicates a superior performance in accuracy for having absolute errors less than 10μm, and relative errors below 4%. It indicates the feasibility of highly accurate non-contact monitoring of physiological movements using Doppler radar.

Cloud and Aerosol Research Capabilities at FARS: The Facility for Atmospheric Remote Sensing

Abstract Since October 1987, the University of Utah Facility for Atmospheric Remote Sensing (FARS) has been applied to the probing of the atmosphere, concentrating on the study of high–level clouds. Regular FARS measurements, which currently total ~3000 h of ruby lidar polarization data, have been directed toward basic cloud research, remote sensing techniques development, and to improving satellite cloud property retrieval methods and GCM predictions by providing climatologically representative cloud datasets and parameterizations. Although the initial studies involved mainly the ruby lidar, the facility has steadily evolved to include a range of visible, infrared, and microwave passive remote sensors, and state–of–the–art, high–resolution dual–wavelength scanning lidar and W–band Doppler radar systems. All three active systems display polarization diversity. In this paper are reviewed the specifications of FARS instrumentation and the research programs to which they have been applied. Four multiple remo...

The 1997 Pan American Climate Studies Tropical Eastern Pacific Process Study. Part II: Stratocumulus Region*

Abstract An ad hoc experiment in the marine stratocumulus region to the west of Mexico was conducted from 29 August to 6 September 1997 as part of the Pan American Climate Studies Tropical Eastern Pacific Process Study cruise on the National Oceanic and Atmospheric Administration ship Ronald H. Brown after a medical emergency cut short the planned time in the eastern Pacific ITCZ. The joint variation of cloud structure, drizzle, and tropospheric stratification was documented by a combination of three hourly upper air soundings, scanning C—band radar, hourly cloud photography, and visual observation. The sensitive C—band Doppler radar mounted on the ship was able to obtain observations of drizzle cells with regions of greater than 10 dBZ of 2—3—km scale in the horizontal and peak reflectivities of greater than 25 dBZ.

NO signatures from lightning flashes

In situ measurements of cloud properties, NO, and other trace gases were made in active thunderstorms by two research aircraft. Concurrent measurements from a three‐dimensional (3‐D) VHF interferometer and the 2‐D National Lightning Detection Network were used to determine lightning frequency and location. The CHILL Doppler radar and the NOAA‐WP‐3D Orion X band Doppler radar were also used to measure storm characteristics. Two case studies from the (STERAO) Stratosphere‐Troposphere Experiments: Radiation, Aerosols, and Ozone project in northeastern Colorado during the summer of 1996 are presented. Narrow spikes (0.11–0.96 km across), containing up to 19 ppbv of NO, were observed in the storms. Most were located in or downwind of electrically active regions where the NO produced by lightning would be expected. However, it was difficult to correlate individual flashes with NO spikes. A simple model of the plume of NO from lightning is used to estimate NO production from the mean mixing ratio measured in these spikes. The estimates range from 2.0×1020 to 1.0×1022 molecules of NO per meter of flash length.

S band Doppler radar measurements of bathymetry, wave energy fluxes, and dissipation across an offshore bar

The use of a shore‐based microwave Doppler radar for the remote sensing of ocean wave propagation over an offshore sand bar was investigated. The radar yielded high spatial resolution measurements of several quantities of importance in the study of bar dynamics. The spatial variation in wave phase with distance along the radar beam direction was used to calculate bathymetry with sufficient accuracy and resolution to clearly reveal the presence of the bar and the tidal cycle variation of water depth. This real‐time bathymetry enabled the calculation of ocean wave energy fluxes from the radar velocity data. These energy fluxes showed good agreement with predictions from a numerical wave propagation model, except in regions of significant wave breaking, where the discrepancy between measured and modeled fluxes was found to be closely related to the modeled wave dissipation rate.

Measurement of Stratus Cloud and Drizzle Parameters in ASTEX with a Kα-Band Doppler Radar and a Microwave Radiometer

Abstract Data are used from a Kα-band radar and microwave radiometer along with a droplet model to determine the droplet parameters of drizzle and clouds. Drizzle droplet parameters are determined from the zeroth, first, and second moments of the Doppler spectrum. Cloud droplet parameters are determined from the zeroth moment of the Doppler spectrum and the measured integrated liquid water. Measurements of stratus clouds were made during the Atlantic Stratocumulus Transition Experiment (ASTEX) on the island of Porto Santo in the Madeira Islands, Portugal. Potential applications of this technique would be in the long-term monitoring of stratus clouds and in determining the vertical profiles of cloud liquid water, number of cloud droplets, and modal radius.