– Electric Current:
– RF currents have unique properties compared to direct current or lower audio frequency alternating current.
– Energy from RF currents in conductors can radiate as electromagnetic waves, forming the basis of radio technology.
– RF currents tend to flow along the surfaces of conductors due to the skin effect.
– RF currents applied to the body may not cause the same painful sensations as lower frequency currents due to rapid direction changes.
– RF currents can ionize air and create conductive paths, exploited in high frequency units like electric arc welding.
– Applications:
– Radio frequencies are utilized in communication devices such as transmitters, receivers, computers, and mobile phones.
– Carrier current systems, telephony, and control circuits also make use of radio frequencies.
– MOS integrated circuits enable the proliferation of radio frequency wireless telecommunication devices.
– RF energy is applied in medical fields for treatments like diathermy, hyperthermy, and electrosurgery.
– Magnetic resonance imaging (MRI) uses radio frequency fields for imaging.
– Measurement:
– Test apparatus for radio frequencies varies from standard instruments at lower frequencies to more specialized equipment at higher frequencies.
– Mechanical Oscillations:
– Mechanical RF systems, such as mechanical filters and RF MEMS, are not uncommon.
– See Also:
– Amplitude modulation (AM), bandwidth, electromagnetic interference, and electromagnetic spectrum are related to radio frequency.
– EMF measurement, frequency allocation, frequency modulation (FM), plastic welding, and spectrum management are also connected.
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, though other definitions treat microwaves as a separate band from RF. 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, among other uses. Different sources specify different upper and lower bounds for the frequency range.