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Electromagnetic wave wireless power supply

Electromagnetic wave wireless power supply

This principle is not complicated, that is, energy is transmitted to electrical appliances through electromagnetic waves as carriers. Radar and antenna are typical examples. Electromagnetic wave is actually light, and its basic particle is photon. Light has such a characteristic that the higher the frequency of photons, the higher the energy, but the higher the frequency, which means that the higher the directivity of electromagnetic wave (or light wave), the easier it is to be blocked by obstacles. The radio communication we use is to use the energy carried by the radio to transmit information and data, and the wireless power supply must also adopt this principle. There is no other choice.

The basic characteristics of electromagnetic wave mentioned just now are also the basic problems encountered in the development of digital communication. For example, if 5g communication uses high-frequency electromagnetic wave as carrier, such as millimeter wave, it will encounter more serious coverage limitation than 4G low-frequency band.

In addition, to carry hundreds of watts or even kilowatts of power, the power of the wireless transmitter must be several orders of magnitude higher than that of the consumer. Because the electromagnetic wave is radiated and needs to be scattered in all directions, even if it is transmitted with a highly directional antenna, the beam scattering cannot be prevented. As soon as the distance is far away, the power decays rapidly, which everyone has experienced with WiFi.

Therefore, to meet the power demand of an electrical appliance within the coverage of electromagnetic waves, the antenna used to transmit electromagnetic waves may need to be super strong. The power of the sun shining on the earth's surface can not reach this level (think: at least we are not roasted by the sun, and the power of household appliances is enough to roast a piece of meat). The safe power density of human is 1MW / cm2 (1 MW per square centimeter), which is a very low power. A 100 watt electrical appliance needs an area of 100000 square centimeters (10 square meters) to receive. Electromagnetic waves exceeding this power intensity are unsafe for people.

Finally, consumers receiving wireless power supply also need to be equipped with a special receiving antenna. If the antenna is small, it can't match the wavelength of electromagnetic wave. In this way, it brings great difficulties to the appearance design of electrical appliances. Originally, electrical appliances are required to be small, but they have to carry a large antenna, which is simply perverse. After all, energy supply is different from communication. Communication can work as long as there is a little energy, but energy supply requires a lot of energy. The energy is sent out, but the reception is poor, which is also the huge bottleneck of wireless power supply technology.