Different Antenna Designs for Non-Contact Vital Signs Measurement: A Review

Abstract

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.

Bluetooth Signal Attenuation Analysis in Human Body Tissue Analogues

“…However, available examples show that such antennas for 2.4 GHz are more omnidirectional [42]. Different types of patterns have been suggested for 2.4 GHz include axial mode helical, patch, angular ring patch, Yagi patch, dipole array, microstrip patch antennas [43], which should be fully investigated for ingestible or implantable applications regarding their radiation patterns.…”

Non-Contact Driver Respiration Rate Detection Technology Based on Suppression of Multipath Interference with Directional Antenna

“…In order to reduce the multipath effect on the system, the reasonable electromagnetic wave path must be designed, and the electromagnetic wave path should be considered from the antenna installation and radiation pattern. Gouveia discussed different antenna designs for non-contact vital signal measurements, and the directivity and gain of antennas were proved to be very important in the system [26]. It was proved by many applications; for example, Comite used a directional wideband antenna to gather ground-penetrating radar data [27].…”

Dynamic Digital Signal Processing Algorithm for Vital Signs Extraction in Continuous-Wave Radars

“…Firstly proposed in the 1970s decade by Lin et al [1][2][3][4], the bio-radar system has been seen as a new research topic within the scientific community, where several solutions have been proposed for its implementation. For instance, the is literature that indicates that it can be operated using different carrier frequencies [5,6] and with different radar front-ends, from Continuous-Wave (CW) or Frequency-Modulated Continuous-Wave (FMCW), to pulsed radars as the ones operating in the Ultrawide Band (UWB) [7].…”

“…The usage of CW radars also allows the use of reduced bandwidth, increasing the flexibility for the antenna selection and design [6]. Furthermore, the usage of CW radars allows the vital signs esstimation through phase measurements, which provides high precision results according to [9].…”