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    Communications 4 min read

    Radio frequency (RF) is a representation of the oscillation rate of the electromagnetic spectrum measured in hertz (Hz).

    How is RF created?

    Radio frequency is created when an alternating current (AC) passes through a conductive material. It is widely used in communications and broadcasting applications such as transmitters and antennas. The waves are characterized by their length (centimeters) and frequency (Hz). The wavelength and frequency are inversely proportional to each other which means if the frequency increases, the wavelength decreases. When the radio frequency is transmitted it is not visible or audible to humans. 

    Properties of Radio Frequency

    One of the core properties of radio frequency is that it can radiate into space as radio waves. Another property of radio frequency is highlighted in the skin effect, in which RF is shown to not penetrate deep into electrical conductors. Instead, it flows along the surface of the conductor. However, radio frequencies have the ability to ionize the air, making a conductive path.

    Another property of radio frequency is that it can be blocked by a bend in wire or coil wire. It also has the ability to reflect and travel back down cable towards the source.

    How is RF used?

    Aside from radio receivers, many kinds of technologies rely on RF field propagation to transmit and receive data. These include mobile phones, remote controls, microwave ovens, computers, smart home devices, satellites, and transceivers, among others. Bluetooth and wireless LANs (WLANs) also operate using radio frequencies.

    Other applications of radio frequency include contactless debit and credit card use, automobile immobilizers, RFID inventory tags, door access cards, ePassport and security cards, transit payments, and toll payment tags.

    RF and medicine

    Radio frequency does not cause any sensation of pain in the human body, making it useful in several medical applications.

    Radio frequency has been used in medical applications for over a century. The proper radio frequency allows it to be used for minimally invasive surgeries and other medical procedures. Some of the most common applications of radio frequency include the treatment of cancer, diathermy, ablation procedure, and more.

    Radio frequency is also used to reshape the cornea to help correct vision. It is also commonly used in cosmetic procedures such as skin tightening, apoptosis, and reducing fat by lipolysis.

    RF ranges: How is RF measured?

    One hertz is equal to one cycle per second, and most radio frequencies are measured in hundreds, thousands, millions, or billions of cycles per second. Radio frequencies are able to carry data over electromagnetic fields via specialized antennas and transmitters.

    RF in particular is a measurement of the oscillation rate of the electromagnetic radiation spectrum ranging from around 9 kHz to 300 GHz. However, different sources specify different ranges for radio frequency with some sources specifying the lower limit to be as low as 3 kHz. 

    The radio frequency spectrum was given a formal naming structure by the International Telecommunications Union (ITU) in the 1800s. The language that designates each band in the spectrum is very specific and should be used carefully. The RF spectrum is as follows:

    • Tremendously low frequency (TLF): < 3Hz
    • Extremely low frequency (ELF): 3-30 Hz
    • Super low frequency (SLF): 30-300 Hz
    • Ultra-low frequency (ULF): 300-3000 Hz (3 kHz)
    • Very low frequency (VLF): 3-30 kHz
    • Low frequency (LF): 30-300 kHz
    • Medium frequency (MF): 300-3000 kHz (3 MHz)
    • High frequency (HF): 3-30 MHz
    • Very high frequency (VHF): 30-300 MHz
    • Ultra-high frequency (UHF): 300-3000 MHz (3 GHz)
    • Super high frequency (SHF): 3-30 GHz
    • Extremely high frequency (EHF): 30-300 GHz
    • Tremendously high frequency (THF): 300-3000 GHz (3 THz)

    As indicated in the list above, one kilohertz (kHz) is equal to 1,000 hertz (Hz), one megahertz (MHz) is equal to 1,000 kilohertz, one gigahertz (GHz) is equal to 1,000 megahertz, and one terahertz (THz) is equal to 1,000 gigahertz.

    Is RF harmful?

    Higher radio frequencies are thought to have cancerous effects on the human body after repeated prolonged periods of exposure. However, significant numbers of research organizations have reported that there is either insufficient evidence to establish a causal relationship between radio frequencies and cancer or that there is the potential for radio frequency radiation to have carcinogenic effects.

    However, this is an ongoing field of biomedical research.