This article is about the part of the electromagnetic spectrum. For the technical aspects of communications by this means, see Radiocommunication .
"RF" redirects here. For the chemical element symbol Rf, see Rutherfordium .
Radio frequency ( RF for short ), also called the radio frequency spectrum , is a term applied to the least energetic portion of the electromagnetic spectrum , located between 3 hertz (Hz) and 300 gigahertz (GHz).
The hertz is the unit of measurement of the frequency of the waves, and corresponds to one cycle per second. 2 The electromagnetic waves in this region of the spectrum can be transmitted by applying the alternating current originating from a generator to an antenna .
Starting at 1 gigahertz, the bands fall within the microwave spectrum . Above 300 gigahertz the absorption of electromagnetic radiation by the earth's atmosphere is so high that the atmosphere becomes opaque to it, until, in the so-called infrared and optical frequency ranges , it becomes transparent again.
The ELF, SLF, ULF and VLF bands share the AF ( Audio Frequency ) spectrum , which is between approximately 20 and 20,000 Hertz . However, the latter are pressure waves , like sound, so they travel at the speed of sound over a material medium. While radio frequency waves, being electromagnetic waves , move at the speed of light and without the need for a material medium.
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