Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies, and also encompasses the microwave range. These are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves, so they are used in radio technology, amongus other uses. Different sources specify different upper and lower bounds for the frequency range.

Electric current

Electric currents that oscillate at radio frequencies (RF currents) have special properties not shared by direct current or lower audio frequency alternating current, such as the 50 or 60 Hz current used in electrical power distribution.

Frequency bands

The radio spectrum of frequencies is divided into bands with conventional names designated by the International Telecommunication Union (ITU): ! scope="col" rowspan="2" | Frequency range !! scope="col" rowspan="2" | Wavelength range !! scope="col" colspan="2" | ITU designation !! scope="col" rowspan="2" | IEEE bands ! scope="col" | Full name ! scope="col" | Abbreviation ! scope="row" Rh2 | Below 3 Hz ! scope="row" Rh2 | 3–30 Hz ! scope="row" Rh2 | 30–300 Hz ! scope="row" Rh2 | 300–3000 Hz ! scope="row" Rh2 | 3–30 kHz ! scope="row" Rh2 | 30–300 kHz ! scope="row" Rh2 | 300 kHz – 3 MHz ! scope="row" Rh2 | 3–30 MHz ! scope="row" Rh2 | 30–300 MHz ! scope="row" Rh2 | 300 MHz – 3 GHz ! scope="row" Rh2 | 3–30 GHz ! scope="row" Rh2 | 30–300 GHz ! scope="row" Rh2 | 300 GHz – 3 THz Frequencies of 1 GHz and above are conventionally called microwave, while frequencies of 30 GHz and above are designated millimeter wave. More detailed band designations are given by the standard IEEE letter- band frequency designations and the EU/NATO frequency designations.

Applications

Communications

Radio frequencies are used in communication devices such as transmitters, receivers, computers, televisions, and mobile phones, to name a few. Radio frequencies are also applied in carrier current systems including telephony and control circuits. The MOS integrated circuit is the technology behind the current proliferation of radio frequency wireless telecommunications devices such as cellphones.

Medicine

Medical applications of radio frequency (RF) energy, in the form of electromagnetic waves (radio waves) or electrical currents, have existed for over 125 years, and now include diathermy, hyperthermy treatment of cancer, electrosurgery scalpels used to cut and cauterize in operations, and radiofrequency ablation. Magnetic resonance imaging (MRI) uses radio frequency fields to generate images of the human body.

Non-surgical weight loss equipment

Radio Frequency or RF energy is also being used in devices that are being advertised for weight loss and fat removal. The possible effects RF might have on the body and whether RF can lead to fat reduction needs further study. Currently, there are devices such as trusculpt ID, Venus Bliss and many others utilizing this type of energy alongside heat to target fat pockets in certain areas of the body. That being said, there is limited studies on how effective these devices are.

Measurement

Test apparatus for radio frequencies can include standard instruments at the lower end of the range, but at higher frequencies, the test equipment becomes more specialized.

Mechanical oscillations

While RF usually refers to electrical oscillations, mechanical RF systems are not uncommon: see mechanical filter and RF MEMS.