Naoki Shinohara

For a field experiment on microwave power transmission (MPT) which was jointly conducted by the Radio Atmospheric Science Center of Kyoto University, Robe University, and Kansai Electric Power Company from 1994 to 1995, we had developed and tested a new type of rectenna (rectifying antenna) based on a circular microstrip antenna (CMA). A square shape of array with an area of 3.2 m/spl times/3.6 m was then constructed using the developed rectennas for experiment. The whole rectenna array is compo

Wireless power transfer (WPT) has a long history of over 100 years since the first experiment conducted by Nicola Tesla. However, the most interesting innovation of WPT was born in the 21 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> century. In this decade, near-field WPT commercialization was advanced, and we now use many near-field WPT products, such as wireless chargers for mobile phones and electric vehicles. In the next decade, we c

Wireless power transfer (WPT) technology gained wide recognition over a decade ago following a resonance coupling WPT study conducted by a group at the Massachusetts Institute of Technology (MIT) [1]. WPT was originally proposed by Nicola Tesla at the end of the 19th century [2] based on a study of near-field inductive-coupling WPT and far-field WPT via radio waves. The first patent involving inductive WPT as a wireless charging system was granted in 1894 for the earliest electric vehicle (EV) [

Recent advances in Wireless Power Transmission (WPT) technologies have enabled various engineering applications with potential product implementation. WPT can be utilized to charge batteries in various pieces of equipment without the need for a wired connection. Energy can be harvested from ambient RF and microwave radiation and 1 million kW microwaves can be transmitted from space to the ground.This book covers all the theory and technologies of WPT, such as microwave generators with semi-condu

Wireless power transmission (WPT) is useful technology in near future. There are some kinds of the WPT technologies, WPT via radio waves, resonance coupling, and inductive. Especially the WPT via radio waves is used for multi-purposes from short range to long range application. However, unfortunately it is misunderstood that it is low efficiency and low power. In this paper, I show the theory of beam efficiency between transmitting antennas and receiving antennas and also show some high efficien

Recent studies in Japan have focused on the development of wireless power transmission (WPT) systems that are able to charge electric vehicles (EVs). Some of the WPT systems have inductive coupling, while some have been implemented with resonance coupling. There are also some WPT systems that employ microwaves based on traditional research in this area. In this paper, I review recent progress in the development of WPT systems for EVs in Japan.

Microwave power transmission (MPT) has had a long history before the more recent movement toward wireless power transmission (WPT). MPT can be applied not only to beam-type point-to-point WPT but also to an energy harvesting system fed from distributed or broadcasting radio waves. The key technology is the use of a rectenna, or rectifying antenna, to convert a microwave signal to a DC signal with high efficiency. In this paper, various rectennas suitable for MPT are discussed, including various

Wireless power transmission technology via microwave (microwave power transmission ; MPT) was advanced from 1960's and many researchers which had a dream to realize the space solar power satellite/station (SPS). In Japan, many kinds of the SPS were proposed and designed in recent ten years. We will show the newest Japanese SPS and its characteristics. We also show some results of the recent Japanese MPT experiments, ubiquitous power source, MPT for moving rover, wireless charging system of elect

Various wireless power transmissions (WPT) are applied to charge an electric vehicle (EV). An inductive coupling WPT and resonance coupling WPT are often used. We proposed a WPT via microwave (microwave power transmission; MPT) for the wireless charging of the EV. We, Kyoto University, developed two types of the wireless charging of the EV with microwave. One is short distance system which has been developed from 2003. A microwave transmitter put on a road or a parking place and a microwave rece

In 1994 and 1995, a ground-to-ground microwave power transmission (MPT) experiment was carried out by a group including participants from Kyoto University, Kobe University, and Kansai Electric Power Company. Among the MPT technologies, which are one of the most important key issues for the realization of the Solar Power Satellite, the “rectenna” (rectifying antenna) has been studied to achieve higher efficiency of conversion from microwave to dc We had developed a new rectenna panel which can ef

Abstract This paper describes various wireless power transmission (WPT) technologies including inductive coupling, radio waves, and resonance coupling. Theoretically, these three WPT technologies are similar, in that all of them depend on Maxwell's equations. However, there are pros and cons for each application of the WPT. Therefore, a suitable WPT technology must be selected for each application. Herein, the theory, technologies, and applications of WPT are discussed. WPT is a useful and conve

We need electricity to use wireless information. If we reduce amount of batteries or electrical wires with a wireless power transmission technology via microwave (MPT), it is a green communication system. We Kyoto University propose a Fixed Wireless Access (FWA) system with the MPT with NTT, Japan. In this paper, we show mainly development results of 24GHz rectennas, rectifying antenna, for FWA. We developed some types of the rectennas. Finally we achieve 65% of RF-DC conversion efficiency with

USA)[1] and Recent Japanese Models (NASDA[2]; METI[3]; Japan) are among them. Some of them are designed based on a microwave power transmitter with microwave tubes. The electronic tubes such as Klystron or magnetron have high efficiency (&amp;gt;70%) and high power output (over kW). However, the microwave power density at a transmitting antenna element of the SPS is too high ranging from several tens watts/element to a few hundred watts/element. Therefore, we must use a system providing the powe

In 1994 and 1995, a ground-to-ground microwave power transmission (MPT) experiment was carried out by a group including participants from Kyoto University, Kobe University, and Kansai Electric Power Company. Among the MPT technologies, which are one of the most important key issues for the realization of the Solar Power Satellite, the “rectenna” (rectifying antenna) has been studied to achieve higher efficiency of conversion from microwave to dc We had developed a new rectenna panel which can ef