Principle of Radio Frequency
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; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.
- Energy from RF currents in conductors can radiate into space aselectromagnetic waves (radio waves). This is the basis of radio
- radio frequency is measured in units calledhertz (Hz), which represent the number of cycles per second when a radio wave is transmitted. One hertz equals one cycle per second; radio waves range from thousands (kilohertz) to millions (megahertz) to billions (gigahertz) of cycles per second. In a radio wave, the wavelength is inversely proportional to the frequency. Radio frequencies are not visible to the human eye. As the frequency is increased beyond that of the RF spectrum, electromagnetic energy takes the form of microwaves, infrared radiation (IR), visible, ultraviolet, X-rays and gamma rays.
- Many types of wireless devices make use of RF fields. Cordless and cellphones, radio and television broadcast stations, Wi-Fi and Bluetooth, satellite communications systems and two-way radios all operate in the RF spectrum. In addition, other appliances outside of communications, including microwave ovens and garage door openers, operate at radio frequencies. Some wireless devices, like TV remote controls, computer keyboards and computer mice, operate at IR frequencies, which have shorter electromagnetic wavelengths.