microwave, electromagnetic wave having a frequency range from 1,000 megahertz (MHz) to 300,000 MHz, corresponding to a wavelength range from 300 mm (about 12 in.) to 1 mm (about 0.04 in.). Like light waves, microwaves travel essentially in straight lines. They are used in radar, in communications links spanning moderate distances, and in other applications, such as microwave ovens microwave oven, device that uses microwaves to rapidly cook food. The microwaves cause water molecules in the food to vibrate, producing heat, which is distributed through the food by induction. A special electron tube called a magnetron produces the microwaves.
..... Click the link for more information. . The equipment used to generate, process, and transmit microwaves is in many respects different from that used with lower frequency radio waves. See waveguide waveguide, device that controls the propagation of an electromagnetic wave so that the wave is forced to follow a path defined by the physical structure of the guide.
..... Click the link for more information. ; magnetron magnetron , vacuum tube oscillator (see electron tube) that generates high-power electromagnetic signals in the microwave frequency range. Its operation is based on the combined action of a magnetic field applied externally and the electric field between its
..... Click the link for more information. .
microwave
microwave [′mī·krə‚wāv]
..... Click the link for more information. . The equipment used to generate, process, and transmit microwaves is in many respects different from that used with lower frequency radio waves. See waveguide waveguide, device that controls the propagation of an electromagnetic wave so that the wave is forced to follow a path defined by the physical structure of the guide.
..... Click the link for more information. ; magnetron magnetron , vacuum tube oscillator (see electron tube) that generates high-power electromagnetic signals in the microwave frequency range. Its operation is based on the combined action of a magnetic field applied externally and the electric field between its
..... Click the link for more information. .
microwave
Portion of the electromagnetic spectrum that is situated between radio waves and infrared radiation. Microwaves have wavelengths ranging from 30 cm to 1 mm, corresponding to frequencies from about 1 gigahertz (109 Hz) to 1 terahertz (1012 Hz). They are the principal carriers of television, telephone, and data transmissions between stations on Earth and between the Earth and satellites. Radar beams are short pulses of microwaves used to locate ships and planes, track weather systems, and determine the speeds of moving objects. Microwaves are absorbed by water and fat in foodstuffs and produce heat from the inside (see microwave oven). Materials such as glass and ceramics do not absorb microwaves, and metals reflect them. See also maser.
microwave
A radio signal in the frequency range from 1 to 40 GHz or from 1 to 300 GHz, depending on the rating system. Numerous transmission systems use microwaves including line-of-sight between buildings and across vast distances, as well as communications satellites, cellular systems and wireless LANs. See spectrum. |
| Early Microwave Tower |
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| Line-of-sight microwaves were first used to transmit across long distances where the terrain was too difficult to lay cable. This tower was installed in 1969 in Boulder Junction, Colorado. (Image courtesy of AT&T.) |
microwave
a. electromagnetic radiation in the wavelength range 0.3 to 0.001 metres: used in radar, cooking, etc.
b. (as modifier): microwave generator
microwave [′mī·krə‚wāv]
(electromagnetism)
An electromagnetic wave which has a wavelength between about 0.3 and 30 centimeters, corresponding to frequencies of 1-100 gigahertz; however, there are no sharp boundaries distinguishing microwaves from infrared and radio waves.
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