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In this paper, the harmonic signals coming from the UHF RFID chips are exploited in two different ways. In the first application, the 3rd harmonic signal is combined with an external signal from a Wi-Fi source (at 2.45 GHz) in order to improve the power conversion efficiency of the energy harvester associated to the tag. In the second method, the 3rd harmonic signal is used alone as an energy source...
This paper studies whether increased ranges of bistatic scatter radio communication are possible, especially when low-cost, embedded receivers, originally designed for conventional radio (and not for scatter radio) are employed. Wireless power transmission and bistatic scatter radio are closely related, and thus, this work aims to highlight a new exciting, potentially interesting, key-enabling research...
High-efficiency rectifier circuit is required for microwave power transfer. In this paper, we studied on the operation of a rectifier circuit with intermittent input signal. Intermittent signal has high peak-to-average power ratio. We can expect an improvement of RF-DC conversion efficiency by using intermittent input signal. However, the operation of a rectifier circuit after the input stopped is...
A silicon carbide (SiC) class E inverter for 6 MHz mid-range inductive power transfer (IPT) has been experimentally shown to offer improvements of 13% in efficiency compared to a previous state-of-the-art silicon (Si) equivalent, whilst delivering 100 W to the load. Using newly available ultra-low gate charge half-bridge GaN modules from Texas Instruments, a custom resonant gate drive has been designed...
This paper proposes inductive power transmission (IPT) system using multiple concatenated parallel-line-feeder (PLF) segments, which is suitable for dynamic charging of moving receivers. The system is HF-driven to exploit strong resonance and self-tuned PLF segments with short lengths are concatenated together to form an elongated primary coil while avoiding impact of standing wave.
In this paper, the design and implementation of a GaN HEMT class-E power amplifier and a Schottky diode class-E rectifier are described. Based on the widely known Linear Amplification with Nonlinear Components technique (LINC), and taking advantage of the spatial power combining capability of a dual-fed square patch, the highly efficient amplifier and rectifier may be incorporated at both sides of...
A novel planar resonant coil elements for the 3×3 array in multi-layer structure is proposed for the wireless power transmitter. Both simulation and measurement results reveal that in comparison with the conventional array of transmitter, the power transfer efficiency does not vary significantly when the receiver is moved along the plane parallel to the transmitter from 50mm to 80mm. The power transfer...
In this paper, we proposed a 915 MHz RF power emitter integrated with a 2×2 patch antenna array, four switchable reflection-type phase shifters with I/Q phase output, a harmonic antenna, and a microcontroller Arduino UNO. To achieve auto location identification, we proposed the rechargeable object which will contain a dual-band Yagi-Uda antenna with a diode to rectify the 915 MHz power and to reflect...
There is a great demand for wireless power transfer (WPT) technology to be embedded in mobile devices because WPT offers the possibility to charge electronic devices without having to plug them into a traditional power outlet. Electric power can be transferred wirelessly using magnetic resonance coupling between two closely spaced coils. Due to the limited space in mobiles units, this paper presents...
This paper proposes and discusses a multiband RF-to-DC converter approach that is simultaneous fed from electromagnetic energy that is available in the ambient, at different frequencies bands, and a dedicated wireless power transmission link. The work uses narrow band matching allowing easy high efficiency conversion on its main power source, which is the WPT link. Its performance is evaluated showing...
This paper presents the use of spread spectrum technique to reduce electromagnetic interference caused by fast switching transitions of a resonant inverter and rectifier used for wireless power transfer (WPT) systems. We investigate the magnetic field emission from a series-resonant WPT system having the resonance frequency of 20 kHz in a frequency band from 9 kHz to 150 kHz. The averaging spectral...
In this paper, we propose electromagnetic interference (EMI) reduction method in tightly-coupled resonant magnetic field automotive charger. The main technique for reducing EMI is input impedance design based on theoretical analysis of tightly coupled wireless power transfer (WPT) circuit. In order to design input impedance of the tightly coupled WPT circuit, the characteristics of the magnitude of...
Wireless power transfer (WPT) technologies are magnetic and capacitive coupling methods, typically. The capacitive coupling WPT has many advantages such as simple structure, low electromagnetic interference and transferring with metal barrier. However, it is hard to reduce the impedance of coupling capacitor for sufficient received output voltage in the capacitive coupling WPT. Therefore, in this...
Magnetic resonance based wireless power transmission using a fractal loop with a three-dimensional structure is evaluated by simulation and experiment. Using a fractal shape optimized with a genetic algorithm, we develop a wireless power transmitting system that can tolerate lateral positioning deviation with a fixed matching circuit.
Metamaterials with negative relative permeability can change magnetic field in the opposite direction. It can also change the magnetic field direction to straight if it has zero relative permeability. Previously reported metamaterials use only single characteristic which is a negative or a zero permeability to enhance efficiency by field confinement in wireless power transfer (WPT) systems. In this...
Power transfer efficiency of wireless power transfer (WPT) system is a primary concern to design and develop the WPT system. However, the power consumption in standby mode is rarely researched and reported in the literature. Since a number of WPT system rapidly increases, it is necessary to develop a standby power reduction technique for WPT system. This paper proposes a standby power reduction method...
This paper presents a wideband and efficient rectenna suitable for 2.4 GHz-band RF energy harvesting from wireless LAN/Wi-Fi or similar devices. We design a stacked patch antenna consisted of a driven patch and four parasitic patches. The proposed antenna performs well both in return loss and gain in the frequency band of 2.41∼2.47 GHz which almost covers all channels of 2.4GHz-band wireless LAN....
Wireless power transfer through a metal object is a major obstacle for the conventionally available tightly coupled inductive system. In this paper, we demonstrate that a metal encased mobile device is enabled for efficient wireless charging using a loosely coupled resonant system. To facilitate this approach, three coils are designed and distributed on a metal phone case and they are tuned for resonance...
An electromagnetic field leaked from WPT systems might cause a false operation of other electronic devices. We have measured and simulated it by using the WPT leakage emulator so far. In this paper, the electromagnetic field is evaluated on the assumption that several WPT systems are located in the residential house and operate simultaneously. It is shown that the simulated results coincide with the...
This paper presents a novel CMOS rectifier for RF energy harvesting. DC-boosted biasing technique is proposed to enhance power conversion efficiency (PCE) by improving forward peak current, reducing diode forward voltage drop and suppressing reverse leakage current. The main rectification diode is configured as threshold compensated diode during on-state whilst the gate voltage is bounded during off-state...
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