<p>In these days, electric vehicles are enthusiastically researched as a countermeasure to air pollution, although these do not have practicality compared to gasoline-powered vehicles. The aim of this study is to transport energy wirelessly and efficiently to an electric vehicle. To accomplish this, we focused on frequency of an alternating current (AC) power supply, and suggested a method which determined the value of it constantly. In particular, a wireless power transfer circuit and a lithium-ion battery in an electric vehicle were expressed with an equivalent circuit, and efficiency of energy transfer was calculated. Furthermore, the optimal frequency which maximizes efficiency was found, and the behavior of voltage was demonstrated on a secondary circuit. Finally, we could obtain the larger electromotive force at the secondary inductor than an input voltage.</p>
A circularly polarized implantable antenna integrated with a voltage-doubled rectifier (abbr., rectenna) is investigated for microwave wireless power transfer in the industrial, scientific, and medical (ISM) band of 2.4–2.48 GHz. The proposed antenna is miniaturized with the dimensions of 7.5 mm × 7.5 mm × 1.27 mm by etching four C-shaped open slots on the patch. A rectangular slot truncated diagonally is cut to improve the circular polarization performance of the antenna. The simulated impedance bandwidth in a three-layer phantom is 30.4% (1.9–2.58 GHz) with |S11| below −10 dB, and the 3-dB axial-ratio bandwidth is 16.9% (2.17–2.57 GHz). Furthermore, a voltage-doubled rectifier circuit that converts RF power to DC power is designed on the back of the antenna. The simulated RF-to-DC conversion efficiency can be up to 45% at the input power of 0 dBm. The proposed rectenna was fabricated and measured in fresh pork to verify the simulated results and evaluate the performance of wireless power transfer.
In this work, we investigate the propagation of magneto-inductive waves (MIWs) in ordering magnetic metamaterial (MM) structures. The proposed non-homogeneous MM slab consists of 9 × 9 MM unit cells constructed from a five-turn spiral embedded on an FR-4 substrate. External capacitors with the value of 40 pF or 50 pF were added to control the resonant frequency of each unit cell in accordance with the waveguide configurations. The characteristics of metamaterial structures, such as negative permeability, current ratio, transmission response, and field distribution in the waveguide, have been thoroughly analyzed by simulation and experiment. Because of the strong magnetic field confinement in the waveguide, the transmittance after nine elements of the non-homogeneous MM slab is 5.2 times greater than that of the homogeneous MM slab. This structure can be applied to the planar near-field wireless power transfer, position sensor, and low-frequency communication.
In the last two decades, metamaterials and metasurfaces have introduced many new electromagnetic (EM) theory concepts and inspired contemporary design methodologies for EM devices and systems. This review focuses on the recent advances in metamaterials (MMs) for simultaneous wireless information and power transmission (SWIPT) technology. In the increasingly complex EM world, digital coding and programmable metamaterials and metasurfaces have enabled commercial opportunities with a broad impact on wireless communications and wireless power transfer. In this review, we first introduce the potential technologies for SWIPT. Then, it is followed by a comprehensive survey of various research efforts on metamaterial-based wireless information transmission (WIT), wireless power transmission (WPT), wireless energy harvesting (WEH) and SWIPT technologies. Finally, it is concluded with perspectives on the rapidly growing SWIPT requirement for 6G. This review is expected to provide researchers with insights into the trend and applications of metamaterial-based SWIPT technologies to stimulate future research in this emerging domain.
Enclosed areas pose a greater risk of transmitting infectious and bacterial diseases. The proposed system helps prevent disease by tracking students’ daily body temperature before entering the school premises. Each student will be provided with a unique QR code containing the student information, such as their name and class. The QR code needs to be scanned first by the camera-equipped smartphone before reading the body temperature. The thermometer will record the student’s body temperature and send the information to the smartphone via Bluetooth. The student’s profile will be updated with the recorded daily temperature. An Android application will be developed to scan the QR code and display the students’ profiles and information. In order to design a battery-less system, the system will be integrated with a wireless power transfer circuit. Based on the simulation results, the wireless power transfer circuit can be used as a wireless charger for the smartphone used in the system or for charging the thermometer’ of the thermometer.
AbstractThe wireless power transfer (WPT) system has been widely used in various fields such as household appliances, electric vehicle charging and sensor applications. A frequency reconfigurable magnetic resonant coupling wireless power transfer (MRCWPT) system with dynamically enhanced efficiency by using the frequency reconfigurable metamaterial is proposed in this paper. The reconfigurability is achieved by adjusting the capacitance value of the adjustable capacitor connected in the coil of the system. Finite element simulation results have shown that the frequency reconfigurable electromagnetic metamaterial can manipulate the direction of the electromagnetic field of the system due to its abnormal effective permeability. The ultra-thin frequency reconfigurable metamaterial is designed at different working frequencies of 14.1 MHz, 15 MHz, 16.2 MHz, 17.5 MHz, 19.3 MHz, 21.7 MHz and 25 MHz to enhance the magnetic field and power transfer efficiency (PTE) of the system. Frequency reconfigurable mechanism of the system with the frequency reconfigurable metamaterial is derived by the equivalent circuit theory. Finally, further measurement which verifies the simulation by reasonable agreement is carried out. PTE of the system by adding the metamaterial are 59%, 73%, 67%, 66%, 65%, 60% and 58% at different working frequencies. PTE of the system with and without the metamaterial is 72% and 49% at the distance of 120 mm and the frequency of 15 MHz, respectively.