In this article, we propose a strategy for the design of a wireless power transfer system consisting of a class-E inverter, a half-bridge class-DE rectifier, and two coupled coils. The system is optimized for maximum power transfer efficiency. The design is validated via a case study, for which a wireless power transfer link to a neuroprosthesis was designed. After circuit simulations, a prototype was realized and measured. There is a good agreement between the calculated, simulated and measured voltages and currents. The prototype delivers ${\text {80}}$ mW, ${\text {7}}$ V to a biomedical implant at ${\text {6.78}}$ MHz, the transfer efficiency is ${\text {52}}$ to 68%, depending on the alignment. The end-to-end efficiency, with the controller and gate driver also taken into account, is ${\text {39}}$ to 57%. Electromagnetic and thermal simulations were performed to verify compliance with relevant safety regulations on specific absorption rate (SAR) levels, magnetic field strength, and heat generation in the implant, for separation distances between the coils of ${\text {8}}$ to ${\text {15}}$ mm, and transverse misalignment from ${\text {0}}$ to $\text {15}$ mm.

This paper reports the analysis, design, prototyping and first measurement results of a linear array antenna consisting of Yagi-Uda elements, rotated and phased for focusing RF power in the near-field of the antenna. By employing Near Field Focusing more power may be transmitted before the EIRP limit is reached due to the inherent far-field difusing. A design based on four Yagi-Uda array elements is able to produce an average power density of 21.04dBm/m2 at 2.45GHz in a box of 10×10×10cm3 located 1m from the linear array face. The design has been verified through comparison with full-wave electromagnetic simulations. First measurements on a realized prototype confirm the functioning of the array.

In this work, we propose a signal processing technique for beam-steering radar architectures allowing concurrent two-dimensional (2-D) localization and vital signs monitoring of human subjects. We demonstrated it by using a single-input single-output (SISO) frequency-modulated continuous wave (FMCW) radar which integrates two frequency-scanning antennas (FSAs). This method is capable of isolating the Doppler signal generated by each single subject from the contributions of all the reflections in the monitored environment. This allows determining the number of individuals in the room and accurately measuring their vital signs parameters (respiration and heart rates) and 2-D positions (range and azimuth information). The spectral analysis, the data matrix generation and the signal processing technique are detailed and discussed. Experimental results demonstrated the feasibility of the proposed approach, showing the ability in determining the number of subjects present in the room, in accurately measuring and tracking over time their vital signs parameters, and in 2-D localization with errors within the limits of the radar range and angular resolutions. Practical applications arise for healthcare, Hospital 4.0, Internet of Medical Things (IoMT), ambient assisted living, smart buildings and through-wall sensing.