Radio Wave

Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Wikipedia.

radio wave

[′rād·ē·ō ‚wāv]
An electromagnetic wave produced by reversal of current in a conductor at a frequency in the range from about 10 kilohertz to about 300,000 megahertz.

Radio Wave


an electromagnetic wave of wavelength greater than 500 micrometers (μm) or of frequency less than 6 × 1012 hertz (Hz). Radio waves have many applications, including radio broadcasting, radiotelephone communications, television, radar, and radio meteorology. In these cases radio waves are a means of wireless transmission of information, which may be in the form of speech, telegraph signals, or images. Radio waves are used to determine the direction and, in range only radar, the distance to various objects. Their other uses include the obtaining of information about the structure of the upper atmospheric layers, the sun, and the planets.

Table 1. Subdivisions of radio spectrum
Subdivision1Wavelength range (m)Frequency range (Hz)
1These subdivisions are discussed in individual articles of the encyclopedia
Superlong waves ......greater than 104less than 3 × 104
Long waves..........104–10333 × 104–3 × 105
Medium waves........103–1023 × 105–3 × 106
Short waves..........102–103 × 106–3 × 107
Meter waves .........10–13 × 107–3 × 108
Decimeter waves ......1–0.13 × 108–3 × 109
Centimeter waves......0.1–0.013 × 109–3 × 1010
Millimeter waves......0.01–0.0013 × 1010–3 × 1011
Submillimeter waves ......103–5 × 10–53 × 1011–6 × 1012

The first experimental transmissions of signals by means of radio waves were carried out by A. S. Popov between 1895 and 1899. Popov used wavelengths of 200 to 500 m—that is, frequencies of 1.5 × 106 to 0.6 × 106 Hz. The subsequent development of radio engineering resulted in the employment of a wider spectrum of electromagnetic waves. The lower limit for the spectrum of radio waves radiated by radio-transmitting devices is of the order of 103–104 Hz.

Many sources of radio waves exist in nature. Examples are the stars, including the sun, the galaxies, the metagalaxy, and the planets. Radio astronomy’s investigation of radio waves from extraterrestrial sources has permitted us to broaden our knowledge of the universe. Some processes that occur within the earth’s atmosphere are also accompanied by the generation of radio waves. For example, radio waves result from lightning discharges (seeATMOSPHERICS) and from the excitation of oscillations in the ionospheric plasma. Such processes can cause the excitation of radio waves of frequencies as low as fractions of a hertz.

Since radio waves of different frequencies propagate differently within the limits of the earth and in outer space, they find different applications in radio communications and in scientific investigations. On the basis of the characteristics of progaga-tion, generation, and—to some extent—processes, the radio spectrum is commonly divided into a number of subdivisions, which are given in Table 1. The basic classification of radio waves into bands for radio communications purposes has been established by the international Radio Regulations. Bands 4 through 11 in Table 2 are used by the various radio services; the designations of the other bands listed are standard Soviet usage.


References in periodicals archive ?
The conference comes in a bid to ensure that radio waves that transmit the media message are free of any undesired interference.
Over the past few years, astronomers have observed a new phenomenon, a brief burst of radio waves, lasting only a few milliseconds.
Bo Thide of the Swedish Institute of Space Physics in Uppsala and Fabrizio Tamburini of the University of Padua led a team that found a way to transmit radio waves in a helical, twisted pattern.
2 delivers a new degree of radio wave propagation prediction performance and accuracy.
A reduction in radio wave leakage has been achieved by placing reflector plates on both sides of the inside of the gate.
These electrons spiral through Earth's magnetic field, emitting radio waves as they do so.
Basically, radar works by sending out radio waves and listening for any that bounce back.
Unlike previous attempts to use body scanning to determine clothing sizes, all of which forced consumers to undress and don a Lycra body suit in order to get measured, the Intellifit System captures measurements directly through clothing using safe, low-power radio waves - about 1/1000th the power of a typical cell phone.
For longer-distance communications, radio wave transmission via satellites has become commonplace.
The array picks up centimeter-long radio wave emissions, the radiation that centimeter-size pebbles would tend to emit.
Our technology meets all FCC requirements, and will present no radio wave interference, thus reassuring those who raised questions about the technology," he added.
Remley, an electronic engineer and leader of the NIST project on radio wave propagation.