Different antenna designs for non-contact vital signs measurement: a review

Cardiopulmonary activity measured through contactless means is a hot topic within the research community. The Doppler radar is an approach often used to acquire vital signs in real time and to further estimate their rates, in a remote way and without requiring direct contact with subjects. Many solutions have been proposed in the literature, using different transceivers and operation modes. Nonetheless, all different strategies have a common goal: enhance the system efficiency, reduce the manufacturing cost, and minimize the overall size of the system. Antennas are a key component for these systems since they can influence the radar robustness directly. Therefore, antennas must be designed with care, facing several trade-offs to meet all the system requirements. In this sense, it is necessary to define the proper guidelines that need to be followed in the antenna design. In this manuscript, an extensive review on different antenna designs for non-contact vital signals measurements is presented. It is intended to point out and quantify which parameters are crucial for the optimal radar operation, for non-contact vital signs' acquisition.info:eu-repo/semantics/publishedVersio

Microwave Doppler Radar for Heartbeat Detection Vs Electrocardiogram

International audienceThis paper presents a contact-less system to detect the heartbeat activity from a distance of one meter. The proposed system is based on using a vector network analyzer. Measurements are performed at 16 GHz for different power levels between 0 and -25 dBm. Results for two S-parameters are obtained and compared to an ECG simultaneous signal in terms of heartbeat rate and heart rate variability

Detection and analysis of human respiration using microwave Doppler radar

 Non-contact detection characteristic of Doppler radar provides an unobtrusive means of respiration detection and monitoring. This avoids additional preparations such as physical sensor attachment or special clothing. Furthermore, robustness of Doppler radar against environmental factors reduce environmental constraints and strengthens the possibility of employing Doppler radar as a practical biomedical devices in the future particularly in long term monitoring applications such as in sleep studies

Detection and analysis of human respiration using microwave Doppler radar

 Non-contact detection characteristic of Doppler radar provides an unobtrusive means of respiration detection and monitoring. This avoids additional preparations such as physical sensor attachment or special clothing. Furthermore, robustness of Doppler radar against environmental factors reduce environmental constraints and strengthens the possibility of employing Doppler radar as a practical biomedical devices in the future particularly in long term monitoring applications such as in sleep studies

Bio-Radar

Mestrado em Engenharia Eletrónica e TelecomunicaçõesNesta dissertação é desenvolvido um protótipo de um bio-radar, cujo foco é a aquisição e processamento do sinal respiratório em tempo real. O sistema do bio-radar permite medir sinais vitais com precisão, baseando-se no princípio do efeito Doppler, que relaciona as propriedades do sinal recebido com a variação da distância percorrida desses sinais. Essa distância está compreendida entre as antenas do radar e a caixa torácica do paciente. No contexto deste projeto, é apresentado o modelo matemático do bio-radar e é também desenvolvido um algoritmo que visa extrair o sinal respiratório tendo em consideração a sensibilidade dos sinais envolvidos tal como o modo de operação do sistema. O protótipo em tempo real desenvolvido nesta dissertação usa um front-end baseado em Software Defined Radio (SDR) e os sinais por ele adquiridos são processados no software LabVIEW da National Instruments.In this dissertation, a prototype of a bio-radar was developed with focus in the real-time acquisition and processing of the respiratory signal. The bio-radar system can measure vital signals accurately by using the Doppler e ect principle that relates the received signal properties with the distance change between the radar antennas and the person's chest-wall. In this framework, a mathematical model of the bio-radar is presented. Also, an algorithm for respiratory rate extraction is proposed having in mind the acquired signal's sensitivity and the system's operation. The real-time acquisition system is developed using a front-end based in SDR and the acquired signals are processed using the LabVIEW software from National Instruments

Radar Range Deception with Time-Modulated Scatterers

Modern radar systems are designed to have high Doppler tolerance to detect fast-moving targets. This means range and Doppler estimations are inevitably coupled, opening pathways to concealing objects by imprinting artificial Doppler signatures on the reflected echoes. Proper temporal control of the backscattered phase can cause the investigating radar to estimate wrong range and velocity, thus cloaking the real position and trajectory of the scatterer. This deception method is exploited here theoretically for arbitrary Doppler tolerant waveforms and then tested experimentally on an example of the linear frequency modulated radar, which is the most common waveform of that class used in practice. The method allows retaining radio silence with a semi passive (battery assisted) approach that can work well with time-dependent metasurfaces. Furthermore, as an insight into new capabilities, we demonstrate that temporally concealed objects could even be made to appear closer than they truly are without violating the laws of relativity