Wireless Power Transfer via Subterahertz-Wave

Mizojiri, Sei; Shimamura, Kazuo

doi:10.3390/app8122653

Cited by 21 publications

(18 citation statements)

References 24 publications

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“…Strongly coupled magnetic resonance, achieved using a tuned intermediate resonator between the transmitter and the receiver, has been demonstrated with high efficiencies at a few meters separation between the coils [16]. [15], coupled magnetic resonance [16], rectennas for UHF WPT [17,18], mmWave, sub-mmWave and THz optical rectennas [19,20].…”

Section: Wpt: the Existing Approachesmentioning

confidence: 99%

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Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

2020

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Achieving a wireless power transfer (WPT) link insensitive to separation is a key challenge to achieving power autonomy through wireless-powering and wireless energy harvesting over a longer range. While coupled WPT has been widely used for near-field high-efficiency WPT applications, the efficiency of the WPT link is highly sensitive to separation and alignment, making it unsuitable for mobile systems with unknown or loose coupling such as wearables. On the other hand, while ultra-high frequency (UHF) and microwave uncoupled radiative WPT (0.3–3 GHz) enables meters-long separation between the transmitter and the receivers, the end-to-end efficiency of the WPT link is adversely limited by the propagation losses. This work proposes radiative WPT, in the 6.78 MHz license-free band, as a hybrid solution to separation-independent WPT, thus mitigating the losses associated with coil separation. Resonant electrically small antennas were fabricated using embroidered textile coils and tuned using L-matching networks, for wearable WPT. The antenna’s efficiency and near-fields have been evaluated numerically and experimentally. The proposed WPT link achieves a stable forward transmission of S 21 > − 17 dB and S 21 > − 28 dB, independent of coil separation on the XZ and XY planes respectively, in a 27 m 3 volume space. The presented approach demonstrates the highest WPT link efficiency at more than 1-m separation and promises higher end-to-end efficiency compared to UHF WPT.

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Section: Wpt: the Existing Approachesmentioning

confidence: 99%

“…Furthermore, this technique allows many receivers to be powered using the same source. At millimeter-wave bands and beyond (THz and infrared) large antenna arrays and nano-rectennas are used in power-beaming applications with power handling capabilities in the kW regime [20].…”

Section: Wpt: the Existing Approachesmentioning

confidence: 99%

Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

2020

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“…The research field of wireless power transfer (WPT) has attracted considerable attention due to the novel batteryfree solutions it could enable in many emerging applications across different domains such as infrastructure robotics, Internet of Things (IoT) devices, and sensor networks [1,2]. A lot of results have already been reported for WPT circuits and systems operating in the sub-6 GHz frequency bands such as 433 MHz, 868 MHz, and 2.4 GHz.…”

Section: Introductionmentioning

confidence: 99%

“…The two major requirements of an efficient wireless power transfer system are a high-gain directional antenna and a rectifier circuit with high RF-DC conversion efficiency [2]. A rectenna is the combination of a receive antenna and a rectifier that together form a complete WPT receiver [1,5]. The overall performance of a WPT system directly depends on the overall efficiency of the rectenna [6].…”

Section: Introductionmentioning

confidence: 99%

Wireless Power Transfer System for Battery-Less Sensor Nodes

et al. 2020

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For the first time, the design and implementation of a fully-integrated wireless information and power transfer system, operating at 24 GHz and enabling battery-less sensor nodes, is presented in this paper. The system consists of an RF power source, a receiver antenna array, a rectifier, and a batteryless sensor node which communicates via backscatter modulation at 868 MHz. The rectifier circuits use commercially available Schottky diodes to convert the RF power to DC with a measured efficiency of up to 35%, an improvement of ten percentage points compared with previously reported results. The rectifiers and the receive antenna arrays were jointly designed and optimised, thereby reducing the overall circuit size. The battery-less sensor transmitted data to a base station realised as a GNU Radio flow running on a bladeRF Software Defined Radio module. The whole system was tested in free-space in laboratory conditions and was capable of providing sufficient energy to the sensor node in order to enable operation and wireless communication at a distance of 0.15 metres.

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“…Many studies have been reported on near field and low frequency WPT. Due to emerging trends of millimter wave (mmW) communications and rapid development of Internet-of-Things devices and sensor nodes, the WPT has grabbed attention in wireless power charging and battery-free solutions in these emerging applications [1,2]. An efficient wireless power transfer system mainly depends on the efficient rectenna (antenna + rectifier) design and specifically a rectifier circuit with high RF-DC conversion efficiency [2].…”

Section: Introductionmentioning

confidence: 99%

Flexible Rectennas for Wireless Power Transfer to Wearable Sensors at 24 GHz

Malik

Doychinov

Zaidi

et al. 2019

2019 Research, Invention, and Innovation Congress (RI2C)

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This paper presents the design and implementation of efficient & compact flexible rectennas (antenna + rectifier) for wireless power transfer to wearable IoT sensor nodes at 24 GHz. Two different rectifier configurations i.e. shunt and voltage doubler have been analyzed for performance comparison. Experimental results of complete rectenna have also been demonstrated for conformal surfaces. The proposed flexible rectifiers is fabricated through conventional PCB manufacturing method. Measured RF-DC conversion efficiency of 31% and DC voltage of up to 2.4 V is achieved for 20 dBm input power across an optimal load resistance of 300Ω at 24 GHz.

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Wireless Power Transfer via Subterahertz-Wave

Cited by 21 publications

References 24 publications

Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

Wireless Power Transfer System for Battery-Less Sensor Nodes

Flexible Rectennas for Wireless Power Transfer to Wearable Sensors at 24 GHz

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