UWB Radar Research Articles

K-Band Single-Path Dual-Mode CMOS Transmitter for FMCW/UWB Radar

A K-band dual-mode radar transmitter is implemented with 0.13- $\mu \text {m}$ CMOS technology, which supports both FMCW and UWB radar operations. A dual-functional block is proposed to achieve efficient dual-mode operation without additional paths and switches. It is switched between a pulse former and a differential amplifier for UWB and FMCW modes, respectively. As a result, the transmit signal can become either a linearly frequency-modulated signal or a time-slotted pulse signal according to the selected mode. It showed performance comparable to that of previously reported transmitters despite the fact that it operates in dual modes.

PCA-based artifact removal algorithm for stroke detection using UWB radar imaging

Stroke patients should be dispatched at the highest level of care available in the shortest time. In this context, a transportable system in specialized ambulances, able to evaluate the presence of an acute brain lesion in a short time interval (i.e., few minutes), could shorten delay of treatment. UWB radar imaging is an emerging diagnostic branch that has great potential for the implementation of a transportable and low-cost device. Transportability, low cost and short response time pose challenges to the signal processing algorithms of the backscattered signals as they should guarantee good performance with a reasonably low number of antennas and low computational complexity, tightly related to the response time of the device. The paper shows that a PCA-based preprocessing algorithm can: (1) achieve good performance already with a computationally simple beamforming algorithm; (2) outperform state-of-the-art preprocessing algorithms; (3) enable a further improvement in the performance (and/or decrease in the number of antennas) by using a multistatic approach with just a modest increase in computational complexity. This is an important result toward the implementation of such a diagnostic device that could play an important role in emergency scenario.

An UWB Radar Signal Processing Platform for Real- Time Human breathing Feature Extraction

Background/Objectives: To evacuate trapped victims in complex environment with the help of UWB to detect the victim whether injured or not even before evacuation. Methods/Statistical Analysis: UWB system was used for sensing the breathing activity. In this process, the primary issue is the definition of design constraints about the signal processing waveform to transmit, correctly for the concerned algorithms for retrieving the breathing frequency and waveform precisely even in worst environment noise. Findings: The observation made from this study showed that more bitwise linear characteristic produced by the captured radar breathing signals than sinusoidal characteristics. Applications/ Improvements: The proposed system helps to find the status of the victim whether dead or alive; healthy or injured

Through Wall Stationary Human Target Detection and Localization Using OFDM-UWB Radar

Abstract This paper focuses on through wall stationary human target detection and localization using an OFDM based Ultra-Wide Band radar (OFDM-UWB). Our investigations relate to a monostatic UWB radar operating in the band [1.99–3] GHz at central frequency 2.5 GHz and emitting a power of –22 dBm, meeting FCC UWB spectrum density requirements. The detection of a human being is possible due to respiratory movements of the chest. Using the short-term Fourier transform, along with the optimal filtering and an averaging technique for background clutter suppression, interesting information could be extracted from the recorded waveforms about the presence and position of a human being behind a 20-cm-thick concrete wall. The results of the experimental simulations under Matlab/simulink are then presented. A maximum range of 4 m was found to be possible with a minimum system operating SNR of 5 dB.

Preliminary study on monitoring the progression of osteoporosis using UWB radar technique in distal femur model

In this Letter, the preliminary study on the progression of osteoporosis using ultra wide band radar technique suggesting two different cases, (1) For various bone thickness and (2) For different effective permittivity is presented. To monitor the progression of osteoporosis, resistively loaded dipole antenna was designed and used as a sensor. For use in targets representing intermediate stages of progression, methanol, ethanol, water, and wood were used for emulating effective dielectric constant of bone in real situation. Measurement results show consistent decrease in the enveloped difference voltage in the two cases which correlate to the loss of bone mineral density. In the future, these results will be useful for people with osteoporosis to predict fractures in advance.

Comparative study of three algorithms for estimation of echo parameters in UWB radar module for monitoring of human movements

The research reported in this paper is related to the ultra-wide-band radar technology that may be employed in care services for elderly and disabled persons. Three algorithms for preprocessing of measurement data from an impulse radar sensor, when applied for such people monitoring, are compared with respect to the uncertainty of estimation of echo parameters. These are: an algorithm based on the maximum-envelope of the measured radar data, an algorithm based on curve-fitting in the spectrum domain of those data, and a modified CLEAN algorithm. Results of the numerical experiments performed on both semi-synthetic data and real-world data, obtained by means of an impulse-radar sensor, are demonstrated.

Experimental Study on Embedded Object Imaging Method with Range Point Suppression of Creeping Wave for UWB Radars

Experimental Study on Embedded Object Imaging Method with Range Point Suppression of Creeping Wave for UWB Radars

Self-sustained UWB Sensing: A Link and Energy Adaptive Approach

Energy efficiency is a challenging issue in autonomous and distributed sensing systems, especially when these systems are powered by renewable energy sources. In this paper, we present a link and energy adaptive UWB-based sensing technique to improve the detection time coverage and detection range coverage for self-sustained embedded applications. The basic idea is derived from the fact that domain-specific information in such applications is often available. Thus, by jointly exploiting the link information between the transmitter and receiver of the UWB pulse radar, and the non-deterministic characteristics of the renewable energy, the proposed technique dynamically adjusts the pulse repetition frequency of the UWB radar to enhance the sustainable operation under the unreliable energy supply. The overhead of the proposed technique is negligible as compared with the overall energy consumption of the UWB pulse radar. It was demonstrated that the proposed technique can achieve much better detection time coverage and detection range coverage than the conventional UWB radar. The proposed technique is also insensitive to many practical issues such as the limited battery capacity.

Bandwidth-Enhanced Grid Array Antenna for UWB Automotive Radar Sensors

This communication presents the design of grid array antenna (GAA) for automotive UWB radar sensors. The proposed GAA is constructed using astroid unit cells, which concurrently achieve high gain and bandwidth. The GAA consists of 33 radiating elements and are excited using a common transmission line center fed by a ${50}\text{-}\Omega $ coaxial probe. Furthermore, amplitude-tapering techniques are employed to lower the sidelobe level (SLL). The prototype antenna is fabricated and experimental results are presented. The developed amplitude-tapered GAA provides 2.5 GHz effective operational bandwidth with ${\text{VSWR}} \leq {2}$ and gain variation less than 3 dB. The measured peak gain is 13.87 dB at 24 GHz.

Noncontact Multiple Heartbeats Detection and Subject Localization Using UWB Impulse Doppler Radar

In this letter, a phase-based algorithm based on a logarithmic method, applicable to UWB radars and suitable to real-time monitoring, is proposed to detect the phase variations of reflected pulses caused by the tiny cardiac motions. Compared with conventional FFT vital signs detection method, this algorithm demonstrates advantage in respiration harmonics suppression and avoidance of intermodulation between respiration and heartbeat signals. Furthermore, it is experimentally shown that UWB Doppler radar is capable of multiple heartbeats detection and subject identification/localization.

Artifact removal algorithms for stroke detection using a multistatic MIST beamforming algorithm.

Microwave imaging (MWI) has been recently proved as a promising imaging modality for low-complexity, low-cost and fast brain imaging tools, which could play a fundamental role to efficiently manage emergencies related to stroke and hemorrhages. This paper focuses on the UWB radar imaging approach and in particular on the processing algorithms of the backscattered signals. Assuming the use of the multistatic version of the MIST (Microwave Imaging Space-Time) beamforming algorithm, developed by Hagness et al. for the early detection of breast cancer, the paper proposes and compares two artifact removal algorithms. Artifacts removal is an essential step of any UWB radar imaging system and currently considered artifact removal algorithms have been shown not to be effective in the specific scenario of brain imaging. First of all, the paper proposes modifications of a known artifact removal algorithm. These modifications are shown to be effective to achieve good localization accuracy and lower false positives. However, the main contribution is the proposal of an artifact removal algorithm based on statistical methods, which allows to achieve even better performance but with much lower computational complexity.

시간-주파수 변환에 요동보상을 적용한 UWB 레이다 바이스테틱 ISAR 이미징

본 논문에서는 시간-주파수 변환에 요동보상을 적용한 UWB 레이다 Bistatic ISAR (Bistatic Inverse Synthetic Aperture Radar: B-ISAR) 이미징에 적용하여 레이다 이미징의 선명도와 품질을 개선하였다. UWB 레이다를 사용하여 제안하는 시간-주파수 알고리즘을 검증하였으며, 이를 위하여 B-ISAR 알고리즘 절차, 시간-주파수 변환과 요동보상 개선 등 필요한 이론적 근거를 제시하였다. B-ISAR 이미징 알고리즘으로 이미지를 생성하였으며, UWB 바이스테틱 ISAR 이미징 생성시 요동보상을 적용한 시간-주파수 변환 기법인 STFT(Short-Time Fourier Transform), GWT(Gabor Wavelet Transform), WVD(Wigner-Ville distribution) 방식을 차례대로 구현하였다. 그리고 STFT, GWT와 WVD 알고리즘을 이용하여 B-ISAR 이미징 알고리즘의 성능을 비교하였으며, 그 결과 WVD가 다른 방식들에 비하여 영상이 선명하고, 퍼짐 현상이 줄어듦을 알 수 있었다. In this paper, we improved the clarity and quality of the radar imaging by applying motion compensation for time-frequency transform in B-ISAR imaging. The proposed motion compensation algorithm using UWB radar is verified. B-ISAR algorithm procedure and time-frequency transform for improved motion compensation are provided for theoretical ground. The image was created by a UWB Radar B-ISAR imaging algorithm method. Also, creating a B-ISAR imaging algorithm for motion compensation of time-frequency transformation method was used. The B-ISAR Imaging algorithm is implemented using STFT(Short-Time Fourier Transform), GWT(Gabor Wavelet Transform), and WVD(Wigner-Ville Distribution) approaches. The performance of STFT is compared with the GWT and WVD algorithms. It is found that the WVD image shows more clarity and decreased spread phenomenon than other methods.

Calibrated Layer-Stripping Technique for Level and Permittivity Measurement With UWB Radar in Metallic Tanks

A method to measure liquid level and electrical properties based on ultra-wideband pulsed radar is developed in this paper. Current methods of material property measurement using free-space radar typically use computationally intensive frequency-domain analysis or finite time-domain methods. The method presented is modified from layer-stripping algorithms and includes several improvements over previous techniques, such as an antenna array that allows measurement in a metallic tank environment and a method of calibration that characterizes path-loss and near-field effects for accurate amplitude-distance prediction. The method presented here also estimates the material loss properties and uses accumulated power with noise compensation to predict reflected pulse power. The method extends the use of pulsed radar for liquid-level measurement in tanks to the evaluation of liquid permittivity and the estimation of liquid height in liquids consisting of multiple layers. The accuracy of the presented method is evaluated using a transmitting single antenna element, a four-element antenna array, and an eight-element antenna array for measurement in a metallic tank environment. Accuracy is improved with larger antenna arrays, but the calibration becomes more critical. The accuracy for varying layer heights and materials is investigated to demonstrate the method reliability.

Looking behind a corner using multipath-exploiting UWB radar

Localization of persons that are hidden behind a corner is important in various security situations when the first responders should not be exposed to any threat. This article demonstrates the feasibility of an ultrawideband multipath-exploitation radar for localization in such scenarios. The approach utilizes multibounce echoes of electromagnetic waves that are scattered by the closest person situated behind a corner. We assume that the person does not carry any tag and does not cooperate with the localization system. The multibounce echoes are reflected and diffracted by the surroundings and make the hidden person visible to an operator that is behind the corner. The location estimation relies only on single-channel time-of-arrival data. Measured data are first processed by a background subtraction algorithm, which reveals the multipath evoked by the person. The multipath echoes are detected by a parallel threshold-based detector. A simple global nearest-neighbor algorithm is used for tracking detected echoes and improving their range estimates. The obtained range estimates are assigned to different physical propagation paths of the electromagnetic waves. The location of the person is estimated by fusing the information of the antenna location with respect to its surroundings and the assigned range estimates. The proposed approach is experimentally verified in a scenario where data are measured in real time by an ultrawideband sensor. Experimental results demonstrate that, depending on the scenario geometry, a walking or calmly standing person can be localized up to several meters behind the corner.

단거리 차량용 초광대역 레이더 송신기의 스펙트럼 분석

In this paper, we propose structures and power spectral densities of UWB radar transmitters of Short Range Automobile. While the conventional transmitters did not consider interferences from self and other automobiles, the proposed method of this paper can minimize interferences. First, we compare a structure of the proposed method with pulse train and pulse compression method. Then, by using mathematical analysis and computer simulations, we show that the proposed method is superior to others. Also we can set proper parameters in UWB radar's transmitter through the numerical method of mathematical results.

UWB 레이더와 비접촉 수면다원검사

The number of people who are suffering from chronic sleep disorder has been growing dramatically in modern era. In order to diagonse the sleep disorder, sleep doctors perform polysomnography: Patients sleep with attaching several vital sign sensors on their body, and doctors monitor the patients in order to find the exact reason of the sleep disorder. Typical polysmonography makes patients sleep with several sensors on their bodies, which prevents the patients from making a comfortable sleep. Furthermore, it is impossible to have a long-term monitoring since the measurements should be done in sleep hosiptal within a few hours. In order to tackle these problems in the typical polysomnography, we envision the development of a non-contact long-term home polysomnography system using UWB radar and related technologies such as multi-modal signal processing.

Texture-Based Automatic Separation of Echoes from Distributed Moving Targets in UWB Radar Signals

A novel algorithm is proposed for separating multiple moving targets in radar images in the slow time-range domain. Target discrimination is based on an image texture angle that is related to the target's instantaneous velocity. The algorithm efficiency has been successfully verified for targets with variable velocities.

Editoral: Special Issue on Photonic and RF Communications Systems

Editoral: Special Issue on Photonic and RF Communications Systems

Overview of UWB Low-Profile Planar Antennas

Historical overview of evolution wideband antennas and some practical realizations of UWB antennas are presented. Practical realization of antennas are made by LTCC technology mostly, PCB technology or their combinations. Main features of antennas such as wide frequency bandwidth, high gain and the smallest dimensions as possible are described. The features should be helpful for future research of described antennas suitable for UWB radar applications.

An Analysis of 2D Positional Accuracy of Human Bodies Detection Using the Movement of Mono-UWB Radar

This paper considers the ability of counting and positioning multi-targets by using a mobile UWB radar device. After a background subtraction process, distinguishing between clutters and human body signals, the position of targets will be computed using weighted Gaussian mixture methods. While computer vision offers many advantages, it has limited performance in poor visibility conditions (e.g., at night, haze, fog or smoke). UWB radar can provide a complementary technology for detecting and tracking humans, particularly in poor visibility or through-wall conditions. As we know, for 2D measurement, one method is the use of at least two receiver antennas. Another method is the use of one mobile radar receiver. This paper tried to investigate the position detection of the stationary human body using the movement of one UWB radar module.