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The history of Wireless Power Transportation (WPT)

In the early sixties, Bill Brown, in the USA, pioneered the field by flying a small helicopter on a microwave beam. Then, in 1968, Peter Glaser invented the SSP concept of Space Solar Power. Many WPT experiments were made in the seventies and later, in the U.S., the DOE proved the feasibility of the SSP concept. New studies were initiated in Japan at the beginning of the nineties, and since 1994, a project is now under way in Reunion Island for the implementation of a first fully operational system to supplement the current photovoltaic energy supply in the small mountain village of Grand-Bassin.

Energy and waves

Ours is a world of energy, which appears basically under two aspects : matter and waves. Waves spread over the electromagnetic spectrum, from the lower frequencies to cosmic rays. All waves carry energy as they radiate : the higher the frequency, the higher the energy of the individual photon. When the energy of wave radiation is absorbed by matter, it is transformed into heat, this is the thermal effect. The most energetic radiation may rip electrons away from atoms and modify the structure of molecules, this is the ionizing effect. Microwaves frequencies are far too low to have ionizing effects.

However the total continuity of the spectrum, three types of radiation are often considered : the radio waves, the optical rays, that travel in a straight line, and the high energy radiation, which have ionizing effects. Hyperfrequencies, also called microwaves, are on the overlap between radio and optics. Just as light, they can be projected.

(to be continued)

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