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

Abstract

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.

Compact Wearable Antenna with Metasurface for Millimeter-Wave Radar Applications

“…It also stands out [ 24 ] for the G and BW that it provides considering its small size, although its performance is outmatched by the proposed antennas. The antenna designs corresponding to ε r values, which are slightly higher than 3 and lower than 3.6, [ 40 , 47 , 48 , 49 , 50 ], provide results of G lower than 14 dBi and with BW similar to that shown by the basic antenna of the present work [ 47 , 48 , 50 ], and in all cases lower than that provided by the antennas with metasurfaces proposed in this work. It can be highlighted [ 48 ] with G = 13 dBi, which could be compared with the basic array proposed here, although [ 48 ] with lower BW and G, and taking up more area despite using a higher ε r .…”

Novel Compact UWB Planar Monopole Antenna Using a Ribbon-Shaped Slot

“…12 provides the simulated and measured radiation efficiencies and some discrepancies are caused by the fabrication and measurement errors. Also, the time-domain behaviors of the proposed antenna are investigated by CST EM simulations [17], [19]- [20], [23], [29]- [30]. The antenna fidelity factor can be obtained by calculating with the cross-correlation between the input pulse and the radiated E-fields.…”

Antenna Design for Microwave and Millimeter Wave Applications: Latest Advances and Prospects

“…In this paper [4], the feasibility study of a 24 GHz industrial, scientific, and medical (ISM) band Doppler radar antenna in electromagnetic aspects was 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.…”