short waves

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short waves,

radio waves whose frequencies range from about 3 to 25 megahertz (Mhz), corresponding roughly to the high-frequency band (see radio frequencyradio frequency,
range of electromagnetic waves with a frequency or wavelength suitable for communication uses. Some of these waves serve as carriers of the lower-frequency audio waves; others are modulated by video or digital information.
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). When they impinge on certain layers of the ionosphere, short waves are largely reflected back toward the earth. By one or more reflections between the earth and the ionosphere, a short-wave radio signal can be received at long distances from the transmitter.
References in periodicals archive ?
Upstream short waves appear as the amplitude of the solitary wave becomes high with time.
6f), the original short waves become long nonlinear waves with larger wavelengths.
We now examine the behaviour of short waves upstream of the solitary wave.
We can directly measure the wavelength of upstream short waves [lambda] using the data at t = 400.
This means that the upstream short waves are almost linear waves, although their amplitude becomes larger for larger Bo, and nonlinear effects should become more significant.
These results show that the upstream short waves are linear waves whose phase speeds are equal to the upstream solitary waves.
The motions of downstream short waves appearing in the depression region are much more irregular and complex than the upstream waves.
Two solutions give qualitative agreement in the generation of the flat elevated wave and the short waves upstream of the obstacle and the downstream short waves in the depression region.
It was found that the capillary effects excite short waves further upstream of the upstream solitary waves.
Verification of background noise in the short wave frequency range according to recommendation ITU-R P.
March 31, 2011 (NAIROBI) -- A Sudanese anti-government youth group announced on Thursday that it has launched a radio on short wave frequencies across the country in order to drum up support for regime change, a bold bid to challenge state control over broadcast media outlets in the country.