What is microwave?

Microwaves refer to a particular band which wavelength is between 1 mm and 1 m. We know that the electromagnetic spectrum is composed of broad spectroscopy which frequency is from low to high. That includes intermediate frequency, high frequency, microwave, infrared, visible light, ultraviolet ray, X-ray and cosmic rays. However, microwave is special frequency band which frequency between ordinary radio waves and infrared ray, which means that its frequency range is from 300MHz to 300GHz.

Microwave characteristics

1. The first feature of microwave is that its wavelengths can be compared with many objects in everyday life. For example, the thickness of our spoon is about 1mm and the height of the table is about 0.8 meters.

2. The second characteristic of microwave is that it is similar to light and it travels along a straight line at a speed of 300,000 km / s per second; when microwave encounters a metal object, it produces reflection or scattering and encountered in the insulating medium, it will penetrate and continue to spread forward, at the same time, produce partial reflection. For different materials, microwave penetration and reflection is not the same.

3. The third feature is that the spread of the microwave does not along the surface of the earth like long wave and medium wave done. Because of the effects of surface soils, vegetation, trees, forests and houses, the transmission distance of both long wave and medium wave is very limited; It is not like shortwave, which propagation often changes with astronomical and meteorological factors. Microwave can easily penetrate the ionosphere without producing a strong reflection, it is always along the straight line forward, so sometimes we call microwave “space wave”.

4. The fourth characteristic is its selectivity in interaction process between microwave and substance. In other words, different nature materials, the performance of interaction between microwave and material is also different. For some substances, such as water, this strongly polar medium, the role of microwave to be much stronger；for some non-polar or weakly polar media, such as ceramics, glass, mica, microwave effect is much smaller. This selectivity is an important basis and principle of currently microwave heating.

5. Its fifth characteristic is that the quantum level is low, and it is not enough to destroy the chemical bonds and molecular structures of the compounds. This is, in recent years, the application basis for microwave in the chemical field being widely used in catalysis, extraction, digestion, synthesis.