The World Book Bonus Science Reference

Short Waves

Short waves are radio waves that have wavelengths shorter than those of waves used in amplitude modulation (AM) broadcast transmissions. The wavelength of a wave is the distance between successive repeated patterns of the wave. Wavelength is related to frequency. As frequency increases, wavelength decreases. Short waves have frequencies higher than 1.7 megahertz--the upper limit of the AM broadcast band. One megahertz (MHz) equals 1 million hertz (cycles per second).

Short waves carry frequency modulation (FM) radio broadcasts, television signals, and transoceanic telephone conversations. Short-wave radios are used by airplane pilots, amateur radio operators, police officers, taxi drivers, and others to send and receive messages.

Short-wave frequencies are divided into several bands. The medium frequency band includes short waves with frequencies up to 3 MHz. The high frequency band ranges from 3 to 30 MHz; the very high frequency band, from 30 to 300 MHz; and the ultrahigh frequency band, from 300 to 3,000 MHz (see Very high frequency waves).

Contributor: Hugh D. Young, Ph.D., Prof. of Physics, Carnegie-Mellon Univ.

See also Radio.

 

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