Radio waves of a frequency of above 1 GHz (wavelength of 30 cm).
Microwave energy supply is one of wireless energy transmission
methods for micromachines. Efficient transmission is possible by the use of a metal pipe as the
waveguide. Microwaves output from the generator propagate through the inside of the pipe, and are
received by the antenna mounted on the end of a micromachine and converted into direct current by a
power converter module, which serves as the power supply for the micromachine. Efforts are being
made to clarify the mechanism of transmission of microwaves through pipes, and to develop compact,
highly efficient transmission-reception antennas, and high withstanding voltage and high frequency
power converter devices. Also, use of microwaves as the information and communication medium for
micromachines is also under consideration.