subject: Another Name For Radio: Electromagnetic Radiation [print this page] In 1865, James Clark Maxwell, a Scottish Physicist postulated the existence of electromagnetic radiation, expanding on research done by Faraday. Heinrich Hertz confirmed Maxwell's theories. No one then could envision the incredible number of applications that would be developed or discovered. Our radiation saturated world, with radio, television, x-rays, microwave communication and remote controls is the result with more and more coming all the time.
Often, explanations of radio and other electromagnetic frequencies are referred to as wavelengths in meters. Switching from frequency to wavelength without explaining the connection is confusing.
Let's simplify it. Light travels at about 3 times ten to the 8th power meters per second or 300,000,000 meters per second. (186,000 miles per hour).
Frequency is the number of waves in a second. The speed of light is the frequency times the wavelength. The frequency is the speed of light divided by the wavelength, and the wavelength is the speed of light divided by the frequency.
Radio is defined as having frequencies below 300 Gigahertz, or 300 billion cycles per second. This is the very lowest end of the electromagnetic spectrum. An alternate, but connected limit is a wavelength longer than one millimeter, (1/1000 of a meter). In the radio spectrum are several bands of wavelengths.
The lowest frequencies have wavelengths longer than 100,000 km, (3 Hz), and so far we don't use them.
The ELF (Extremely , and the SLF, (Super Low Frequencies), are used to send signals underwater, communicating with deep submarine vehicles. (3 Hz to 3,000 Hz)
VLF, (Very Low Frequency), (3,000 to 30,000 Hz), are easier to use, but only covers to a depth of about 130 feet. Used underwater and inside mines, for heart monitors, and underground beacons.
Low frequency is between 30 KHz and 300 KHz. Here we find the commercial band AM radio, navigation frequencies, and time signals.
Medium wave is next. From 300 KHz to 3,000 KHz, (3MHz).
The 7th band contains the CB and amateur wavebands, 27Mhz or 11 meter for CB radio and wavelengths up to 100 meters for 'Hams'.In this band are also some of the frequencies used by emergency services.
The VHF (Very High Frequency) band for TV and FM broadcasts comes next.
UHF (Ultra High Frequency) has more TV, mobile phones, wireless networks for computers, Bluetooth and GPS. Microwave ovens use this frequency range.
EHF, 30 to 300 GHz, (Extremely High Frequency), is used by microwave radio relay towers, and radio astronomers.
The last radio band, between 300 GHz and 3 TeraHertz, is still being investigated for uses. It extends up to the lowest range for infrared light.
Now you know where your CB radio falls in the electromagnetic spectrum.
