Radio frequency

The term radio frequency (RF) (also, radio frequency spectrum) is applied to the least energetic portion of the electromagnetic spectrum, located between both 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. The electromagnetic waves of this region of the spectrum can be transmitted by applying alternating current originated in a generator to an antenna.

Classification

Radio frequency can be divided into the following spectrum bands:

From 1 gigahertz, the bands fall within the spectrum of microwaves. Above 300 gigahertz the absorption of electromagnetic radiation by the Earth's atmosphere is so high that the atmosphere becomes opaque to it, until it becomes transparent again in the so-called infrared and optical frequency ranges.

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, travel at the speed of light and without the need for a material medium.

History

The theoretical bases of electromagnetic wave propagation were first described between 1886 and 1888 by Heinrich Rudolf Hertz, who was the first to experimentally validate Maxwell's theory.

Antennas for radio and television broadcasting in Czechia.

The use of this technology for the first time is attributed to different people: Aleksandr Stepanovich Popov made his first demonstrations in St. Petersburg, Russia; Nikola Tesla, in Saint Louis Missouri, United States, and Guillermo Marconi, in the United Kingdom.^{[citation required]}

The first practical communication system using radio waves was designed by Guillermo Marconi, who in 1901 made the first transatlantic radio transmission. Today, radio takes many other forms, including wireless networks, mobile communications of all kinds, as well as broadcasting.^{[citation needed]}

Uses of radio frequency

Radio communications

AM and FM radio systems.

Although the word radio is used, television, radio, radar and mobile phone transmissions are included in this class of radio frequency emissions. Other uses are audio, video, radio navigation, emergency services and digital radio data transmission; both in the civil and military fields. They are also used by radio amateurs.

Radio Astronomy

Many of the astronomical objects emit in radio frequency. In some cases in wide ranges and in other cases centered on a frequency that corresponds to a spectral line, for example:

• HI line or atomic hydrogen. Hundred at 1,4204058 gigahertz.
• CO line (rotational 1-0) associated with molecular hydrogen. Hundred at 115,271 gigahertz.

Radar

Radar is a system that uses electromagnetic waves to measure distances, altitudes, directions, and speeds of stationary or moving objects such as aircraft, ships, motor vehicles, weather formations, and the terrain itself. Its operation is based on emitting a radio impulse, which is reflected by the target and is typically received in the same position as the emitter. From this "eco" large amount of information can be extracted. The use of electromagnetic waves makes it possible to detect objects beyond the range of other types of emissions. Its fields of application include meteorology, air and ground traffic control and a wide variety of military uses.

Nuclear Magnetic Resonance

Nuclear magnetic resonance studies atomic nuclei by aligning them to a constant magnetic field to later perturb this alignment with the use of an orthogonally oriented alternating magnetic field. The result of this disturbance is an energy difference that is evident when said atoms are excited by electromagnetic radiation of the same frequency. These frequencies typically correspond to the radio frequency range of the electromagnetic spectrum. This is the resonance absorption that is detected in the different NMR techniques.

Medicine

Radiofrequency has been used in medical treatments for the last 75 years, generally for minimally invasive surgery, using radiofrequency ablation or cryoablation. Among the treatments in which radiofrequency is used is against sleep apnea or cardiac arrhythmias.

Diathermy is a technique that uses the heat produced by radiofrequency for surgical treatments, in such a way that it produces tissue coagulation and prevents the tissue from bleeding after the surgical incision. In addition to cauterizing blood vessels to prevent excessive bleeding, the heat produced by diathermy can also be used to destroy tumors, warts, and infected tissue. This technique is particularly valuable in neurosurgery and eye surgery. Diathermy equipment typically operates on shortwave radio frequency (range 1-100 MHz) or microwave energy (range 434-915 MHz).

Beauty treatments

Radiofrequency, at energy levels that do not produce ablation, is also used as a cosmetic treatment to tighten the skin, reduce fat (lipolysis), or promote healing. It is a technique used in beauty centers and aesthetic medicine.

The use of radiofrequency to tighten the skin is based on the fact that energy is produced that heats the tissue, which stimulates the production of subcutaneous collagen and elastin, reducing wrinkles on the skin. On the face, facial radiofrequency is an alternative to surgical lifting and other cosmetic surgeries.

Among the different types of radiofrequency that exist we find: body radiofrequency, monopolar radiofrequency, abdominal radiofrequency, facial abdominal radiofrequency or unipolar radiofrequency. All of them act by overheating the different layers of the skin, so that the different cells are mobilized and thus tighten the dermis, give it a more rejuvenated appearance, promote the creation of new collagen cells as well as migration. of fibroblasts.

So, radiofrequency treatment bases its technique on the emission of electromagnetic waves to achieve all the effects described above. It is a non-invasive method, with minimal side effects and with which to achieve great results in a matter of a few sessions.

Other uses of radio waves

• Heating
• Mechanical strength
• Metallurgy:
  • Metal Template
  • Soldiers
• Food industry:
  • Sterilization of food