微波辐射是一种电磁辐射。微波中的前缀“micro-”并不意味着微波具有微米波长，而是说与传统无线电波相比，微波具有非常小的波长（1毫米到100000公里的波长）。在电磁频谱中，微波介于红外辐射和无线电波之间。

频率

微波辐射的频率在300兆赫至300千兆赫（无线电工程中为1千兆赫至100千兆赫）之间，或波长在0.1厘米至100厘米之间。范围包括SHF（超高频）、UHF（超高频）和EHF（超高频或毫米波）无线电频段。

虽然低频无线电波可以沿着地球的轮廓线传播，并在大气层中反射，但微波只能在视线范围内传播，在地球表面的传播距离通常限制在30-40英里。微波辐射的另一个重要特性是它被水分吸收。在微波波段的高端会出现一种称为雨衰减的现象。超过100GHz时，大气中的其他气体吸收能量，使空气在微波范围内不透明，尽管在可见光和红外区域是透明的。

乐队名称

由于微波辐射包含如此宽的波长/频率范围，它被细分为IEEE、NATO、EU或其他雷达波段名称：

Uses

Microwaves are used primarily for communications, include analog and digital voice, data, and video transmissions. They are also used for radar (RAdio Detection and Ranging) for weather tracking, radar speed guns, and air traffic control. Radio telescopes use large dish antennas to determine distances, map surfaces, and study radio signatures from planets, nebulas, stars, and galaxies. Microwaves are used to transmit thermal energy to heat food and other materials.

Sources

Cosmic microwave background radiation is a natural source of microwaves. The radiation is studied to help scientists understand the Big Bang. Stars, including the Sun, are natural microwave sources. Under the right conditions, atoms and molecules can emit microwaves. Man-made sources of microwaves include microwave ovens, masers, circuits, communication transmission towers, and radar.

Either solid state devices or special vacuum tubes may be used to produce microwaves. Examples of solid-state devices include masers (essentially lasers where the light is in the microwave range), Gunn diodes, field-effect transistors, and IMPATT diodes. The vacuum tube generators use electromagnetic fields to direct electrons in a density-modulated mode, where groups of electrons pass through the device rather than a stream. These devices include the klystron, gyrotron, and magnetron.

Reference

• Andjus, R.K.; Lovelock, J.E. (1955). "Reanimation of rats from body temperatures between 0 and 1 °C by microwave diathermy". The Journal of Physiology. 128 (3): 541–546.

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Helmenstine, Anne Marie, Ph.D. "Microwave Radiation Definition." ThoughtCo, Aug. 12, 2021, tl80.cn/microwave-radiation-definition-4145800. Helmenstine, Anne Marie, Ph.D. (2021, August 12). Microwave Radiation Definition. Retrieved from https://www.tl80.cn/microwave-radiation-definition-4145800 Helmenstine, Anne Marie, Ph.D. "Microwave Radiation Definition." ThoughtCo. https://www.tl80.cn/microwave-radiation-definition-4145800 (accessed September 2, 2021).

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