microwave

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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 ovensmicrowave 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.
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. The equipment used to generate, process, and transmit microwaves is in many respects different from that used with lower frequency radio waves. See waveguidewaveguide,
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. Waveguides, which are useful chiefly at microwave frequencies in such applications as connecting the output
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; magnetronmagnetron
, 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 electrodes.
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.

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.

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

Meaning "small wave," a microwave is a radio signal in the frequency range from 300 MHz to 300 GHz or from 1 to 300 GHz, depending on the rating system. Except for AM and FM radio, shortwave radio and over-the-air TV, almost all other communications systems transmit microwaves, including satellites, cellular systems, wireless LANs and line-of-sight between buildings and across vast distances. See spectrum and millimeter wave.


Early Microwave Tower
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.)
References in periodicals archive ?
Effect of microwave radiation on Bacillus subtilis spores.
[Effects of the microwave radiation from the cellular phones on humans and animals].
Environmental campaign group Friends of the Earth has warned that long-term exposure to microwave radiation could cause cancers and childhood leukaemia.
The dispersion was exposed to microwave radiation for 5-40 minutes in a domestic microwave oven (BPL India, micro convention system, 2.45GHz, 800W power).
The research studied what effect, except that caused by a rise in temperature, microwave radiation has on cells.
With the advent of the cell phone in the 1990s, however, a new generation of fearmongers appeared, insisting that microwave radiation from handheld cell phones was inducing brain cancer.
The properties include the static effect of magnetization, but also dynamic phenomena such as interactions with microwave radiation. Our experiment measures such a behavior in the microwave frequency regime (35-55 GHz) characterized by frequency-dependant absorption of microwave power in ultra-thin iron and copper/cobalt films placed in a magnetic field.
ME differs from SFE and PSE in that microwave radiation is used to heat the sample, whereas SFE exposes the sample to a supercritical fluid and PSE immerses the sample in a solvent heated above its boiling point.
Cell phones use low-level microwave radiation to communicate between the caller and a base station.
Held too close, as much as 60% of the microwave radiation is absorbed by and actually penetrates the brain.
The microwave lesson-plan provides an introduction to microwaves, and then discusses: various sources of microwave radiation; biological effects; microwave monitoring equipment; and control of microwave hazards.
It does this by using frequency-tunable microwave radiation transmitted into the furnace from outside areas.

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