A waveguide is a tube that allows waves to pass through, so it can be used for both sound waves and visible light, but it is generally used as the name of a tube for passing electromagnetic waves with wavelengths near microwaves, and its shape is square or circular. It is a tube with a cross section of.

Microwaves are used in microwave ovens and are electromagnetic waves that are highly effective in warming objects. However, due to the long wavelength, optical fibers cannot be used, and it is necessary to use a dedicated microwave waveguide when sending from the microwave source to the processing system.

Usage of waveguide

When using a waveguide, it is often a high-power microwave generator. At low output, a magnetron, which is a microwave generator, is installed inside the housing like a household microwave oven and can be directly irradiated. However, if the output is high, the magnetron itself will be destroyed by the microwave, so it is necessary to perform irradiation processing at another location. For this reason, the waveguide is connected to the processing room for processing such as heating, and microwaves are supplied.

Waveguides are also used in radar and are used as slot antennas, which are radio wave irradiation devices.

Waveguide principle

Light has the property that it becomes difficult for light to pass through holes smaller than the wavelength, and the smaller it becomes, the more difficult it is for light to pass through. Microwaves have a wide range of definitions, but electromagnetic waves with a frequency of 2.45 GHz, which are generally used in microwave ovens, also enter microwaves. The wavelength of electromagnetic waves in a microwave oven is 12.2 cm, and the microwave in this case is also called a cutoff, but it cannot pass through a hole of about 6 cm, which is half the wavelength.

In other words, if you want to pass microwaves from a microwave oven, the diameter of the waveguide needs to be about the wavelength, and the longer the wavelength of the microwave, the larger the diameter of the waveguide. In this way, the waveguide is designed based on the wavelength of the microwave.

A tube with a square cross section is often used as the shape of the waveguide, but there is also a circular waveguide. There are also ridge-type waveguides used for special purposes.

The microwave introduced into the waveguide repeats reflection on the wall inside the tube and travels. This also has the advantage of reducing microwave loss.

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