Microwave Energy Transmission (Applied Radio Engineering for Humansphere/Shinohara Lab)

Research and development of microwave power transmission and radio applications

Microwave power transmission is a power transmission technology, by which electricity is wirelessly tranmitted via microwave. We are studying on microwave power transmission systems for terrestrial radio applications and for "Solar Power Sattellite/Station" concept. We are also studying on space plasma waves and microwave heating applications.

Related Subjects: Microwave engineering, Radio enginnering, Communication engineering, Electromagnetics, Electronic circuit, Signal processing, Automatic control engineering, etc.

Academic Staff


Professor (Research Institute for Sustainable Humanosphere)

Research Interests


TEL: +81-774-38-3807
FAX: +81-774-31-8463
E-mail: shino@rish.kyoto-u.ac.jp

Tomohiko MITANI

Tomohiko MITANIAssociate Professor (Research Institute for Sustainable Humanosphere)

Research Interests

  • Microwave power transmission
  • Magnetron (Microwave tube)
  • Microwave heating application


Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011
TEL: +81-774-38-3880
FAX: +81-774-31-8463
E-mail: mitani/henkan/rish.kyoto-u.ac.jp (/henkan/ -> @)

Introduction to R&D Topics

Microwave power transmisson systems

Microwave is a type of radio waves, whose wave length is 30cm to 1cm and whose frequency is 1GHz to 30GHz ("G" means 10 to the 9th power.).  Microwave is widely used  for a lot of radio applications in our living environment; mobile phones, wireless LAN, satellite broadcasting, microwave ovens, etc. We are studying on microwave power transmission sytems as a new microwave application.

Onging topics on microwave power transmission systems are as follows;

  • Ubiquitous power services: microwave power transsmision for small devices
  • Microwave power charging system for electric vehicles
  • Microwave power distribution system in a building
  • Microwave power transmission systems for Solar Power Satellite

Solar Power Station/Satellite
Conceptual Image of Solar Power Station/Satellite

MW Charging for EV
Microwave Power Charging for an Electric Vehicle

R&D of transmitting systems and receiving systems (rectennas) for microwave power transmission

We are studying on microwave power transmitting sytems with solid state devices or microwave tubes. Requirements for the transmitting sytems are low loss, low noise, frequency & phase stability, etc. We have developed highly-efficient and low-cost transmitting systems with magnetron (which is widely used as a microwave power source of a microwave oven), and compact, light-weight, and multi-functional transmitting systems with solid state devices.

Also, we are studying on microwave power receiving sytems so called "rectennas". Requirements for the rectennas are low loss, small in size, high-power or low-power rectification etc. We conduct these studies through circuit designing, experimental production and measurement.

Microwave Rectifying Circuit
High-Power Microwave Rectifying Circuit

Beam control technology with a large number of antennas

In some microwave power transmission systems, a pilot signal is transmitted from a receiving site to the transmitting site, and microwave power is transmitted to the direction which the pilot signal comes from. This is called "retro-irective" system. For highly-efficient and precise microwave power transmission, we are studying on retro-directive systems and beam control technology without a pilot signal, beam forming algorithm of phased antenna array for low sidelobe level.

Research on plasma waves by scientific satellites satellites

Low frequency waves up to 1 MHz are observed by the lunar orbiter, "KAGUYA" launched in September, 2007. Plasma wave phenomena in wakes created by the solar wind at the back of the moon and wave phenomena in the magnetosphere and the solar wind are studied. By the Geotail satellite launched in 1992, the plasma waves with mainly several 100-kHz which come out from the auroral region and those from the equatorial region which was discovered by ourselves are studied. Comparison of the oservation results by both satellites offers valuable information.

Microwave heating applications

Microwave heating is a kind of heating methods and it is expected as an energy-saving heating, because materials can be evenly heated in a short time.

We are studying on the following microwave heating applications;

  • Development of a microwave irradiation system for bio-ethanol production from woody biomass
  • Development of a microwave heating system for material processing

MW Irradiation System for Woody Biomass
Microwave Irradiation System for Bio-ethanol Production from Woody Biomass