Microwave is a kind of electromagnetic wave with the frequency of 300mhz-3000ghz. It is the abbreviation of a limited frequency band in the radio wave, that is, the electromagnetic wave with the wavelength of 0.1mm-1m. Microwave frequency is higher than general radio wave frequency, which is also called “UHF electromagnetic wave”. As a kind of electromagnetic wave, microwave also has wave particle duality. The basic properties of microwave are penetration, reflection and absorption. For glass, plastic, and porcelain, microwaves almost pass through without being absorbed. For water and food, it will absorb microwave and make itself hot. And for metals, they reflect microwaves.