Радиоспектр: жиіліктер, қолданылуы және реттелуі

Part of the electromagnetic spectrum from 1 Hz to 3000 GHz
the spectral band

The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum). Because it is a fixed resource which is in demand by an increasing number of users, the radio spectrum has become increasingly congested in recent decades, and the need to utilize it more effectively is driving modern telecommunications innovations such as trunked radio systems, spread spectrum, ultra wideband, frequency reuse, dynamic spectrum management, frequency pooling, and cognitive radio.

The frequency boundaries of the radio spectrum are a matter of convention in physics and are somewhat arbitrary. Since radio waves are the lowest frequency category of electromagnetic waves, there is no lower limit to the frequency of radio waves. Radio waves are defined by the ITU as: "electromagnetic waves of frequencies arbitrarily
lower than 3000 GHz, propagated in space without artificial guide". At the high frequency end the radio spectrum is bounded by the infrared band. The boundary between radio waves and infrared waves is defined at different frequencies in different scientific fields. The terahertz band, from 300 gigahertz to 3 terahertz, can be considered either as microwaves or infrared. It is the highest band categorized as radio waves by the International Telecommunication Union. So although the radio spectrum is becoming increasingly congested, there is no possible way to add additional frequency bandwidth outside of that currently in use.

A radio band is a small frequency band (a contiguous section of the range of the radio spectrum) in which channels are usually used or set aside for the same purpose. To prevent interference and allow for efficient use of the radio spectrum, similar services are allocated in bands. For example, broadcasting, mobile radio, or navigation devices, will be allocated in non overlapping ranges of frequencies.

The actual authorized frequency bands are defined by the ITU and the local regulating agencies like the US Federal Communications Commission (FCC) and voluntary best practices help avoid interference. As a matter of convention, the ITU divides the radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten (10n) metres, with corresponding frequency of 3×108−n hertz, and each covering a decade of frequency or wavelength. Each of these bands has a traditional name. For example, the term high frequency (HF) designates the wavelength range from 100 to 10 metres, corresponding to a frequency range of 3 to 30 MHz. This is just a symbol and is not related to allocation; the ITU further divides each band into subbands allocated to different services. Above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that the atmosphere is effectively opaque, until it becomes transparent again in the near infrared and optical window frequency ranges. These ITU radio bands are defined in the ITU Radio Regulations. Article 2, provision No. 2.1 states that "the radio spectrum shall be subdivided into nine frequency bands, which shall be designated by progressive whole numbers in accordance with the following table". The table originated with a recommendation of the fourth CCIR meeting, held in Bucharest in 1937, and was approved by the International Radio Conference held at Atlantic City, NJ in 1947. The idea to give each band a number, in which the number is the logarithm of the approximate geometric mean of the upper and lower band limits in Hz, originated with B. C. Fleming Williams, who suggested it in a letter to the editor of Wireless Engineer in 1942. For example, the approximate geometric mean of band 7 is 10 MHz, or 107 Hz. The band name "tremendously low frequency" (TLF) has been used for frequencies from 1–3 Hz (wavelengths from 300,000–100,000 km), but the term has not been defined by the ITU. Band name Abbreviation ITU band number Frequency and wavelength Example uses Extremely low frequency ELF 1 Communication with submarines Super low frequency SLF 2 Communication with submarines Ultra low frequency ULF 3 Communication with submarines, communication within mines, landline telephony, fax machines, fiber optic communication Very low frequency VLF 4 Navigation, time signals, communication with submarines, landline telephony, wireless heart rate monitors, geophysics Low frequency LF 5 Navigation, time signals, AM longwave broadcasting (Europe and parts of Asia), RFID, amateur radio. Medium frequency MF 6 AM (medium wave) broadcasts, amateur radio, avalanche beacons, magnetic resonance imaging, positron emission tomography, electrical telegraph, wireless telegraphy, radioteletype, dial up internet. High frequency HF 7 Shortwave broadcasts, citizens band radio, amateur radio, over the horizon aviation communications, RFID, over the horizon radar, automatic link establishment (ALE) / near vertical incidence skywave (NVIS) radio communications, marine and mobile radio telephony, CT scan, magnetic resonance imaging, positron emission tomography, ultrasound, cordless phones. Very high frequency VHF 8 FM broadcasts, television broadcasts, cable television broadcasting, radars, line of sight ground to aircraft, aircraft to aircraft communications, emergency locator beacon homing signal, radioteletype, land mobile and maritime mobile communications, amateur radio, police, fire and emergency medical services broadcasts, weather radio, CT scan, magnetic resonance imaging, positron emission tomography, ultrasound, cordless phones. Ultra high frequency UHF 9 Television broadcasts, cable television broadcasting, microwave oven, radars, microwave devices/communications, radio astronomy, radars (L band), mobile phones, wireless LAN, Bluetooth, Zigbee, GPS and two way radios such as land mobile, emergency locator beacon, FRS and GMRS radios, amateur radio, satellite radio, police, fire and emergency medical services broadcasts, remote control systems, ADSB, cordless phones, internet, dial up internet, satellite broadcasting, communication satellites, weather satellites, satellite phones (L band), satellite phones (S band). Super high frequency SHF 10 Radio astronomy, microwave devices/communications, wireless LAN, DSRC, most modern radars, communications satellites, cable and satellite television broadcasting, DBS, amateur radio, satellite broadcasting, communication satellites, weather satellites, satellite radio, cordless phones, internet, satellite phones (S band). Extremely high frequency EHF 11 Radio astronomy, satellite broadcasting, communication satellites, weather satellites, high frequency microwave radio relay, microwave remote sensing, directed energy weapon, millimeter wave scanner, Wireless Lan 802.11ad, internet. Terahertz or tremendously high frequency THF 12 Experimental medical imaging to replace X rays, ultrafast molecular dynamics, condensed matter physics, terahertz time domain spectroscopy, terahertz computing/communications, remote sensing

Band Frequency range R band 1.70 to 2.60 GHz D band 2.20 to 3.30 GHz S band 2.60 to 3.95 GHz E band 3.30 to 4.90 GHz G band 3.95 to 5.85 GHz F band 4.90 to 7.05 GHz C band 5.85 to 8.20 GHz H band 7.05 to 10.10 GHz X band 8.2 to 12.4 GHz 12.4 to 18.0 GHz K band 18.0 to 26.5 GHz 26.5 to 40.0 GHz Q band 33 to 50 GHz U band 40 to 60 GHz V band 50 to 75 GHz E band 60 to 90 GHz W band 75 to 110 GHz F band 90 to 140 GHz D band 110 to 170 GHz Y band 325 to 500 GHz

Airband refers to VHF frequencies 108 to 137 MHz, used for navigation and voice communication with aircraft. Trans oceanic aircraft also carry HF radio and satellite transceivers.

The greatest incentive for development of radio was the need to communicate with ships out of visual range of shore. From the very early days of radio, large oceangoing vessels carried powerful long wave and medium wave transmitters. High frequency allocations are still designated for ships, although satellite systems have taken over some of the safety applications previously served by 500 kHz and other frequencies. 2182 kHz is a medium wave frequency still used for marine emergency communication. Marine VHF radio is used in coastal waters and relatively short range communication between vessels and to shore stations. Radios are channelized, with different channels used for different purposes; marine Channel 16 is used for calling and emergencies.

Amateur radio frequency allocations vary around the world. Several bands are common for amateurs worldwide, usually in the HF part of the spectrum. Other bands are national or regional allocations only due to differing allocations for other services, especially in the VHF and UHF parts of the radio spectrum.

Citizens' band radio is allocated in many countries, using channelized radios in the upper HF part of the spectrum (around 27 MHz). It is used for personal, small business and hobby purposes. Other frequency allocations are used for similar services in different jurisdictions, for example UHF CB is allocated in Australia. A wide range of personal radio services exist around the world, usually emphasizing short range communication between individuals or for small businesses, simplified license requirements or in some countries covered by a class license, and usually FM transceivers using around 1 watt or less.

The ISM bands were initially reserved for non communications uses of RF energy, such as microwave ovens, radio frequency heating, and similar purposes. However, in recent years the largest use of these bands has been by short range low power communications systems, since users do not have to hold a radio operator's license. Cordless telephones, wireless computer networks, Bluetooth devices, and garage door openers all use the ISM bands. ISM devices do not have regulatory protection against interference from other users of the band.

Bands of frequencies, especially in the VHF and UHF parts of the spectrum, are allocated for communication between fixed base stations and land mobile vehicle mounted or portable transceivers. In the United States these services are informally known as business band radio. See also Professional mobile radio. Police radio and other public safety services such as fire departments and ambulances are generally found in the VHF and UHF parts of the spectrum. Trunking systems are often used to make most efficient use of the limited number of frequencies available. The demand for mobile telephone service has led to large blocks of radio spectrum allocated to cellular frequencies.

Reliable radio control uses bands dedicated to the purpose. Radio controlled toys may use portions of unlicensed spectrum in the 27 MHz or 49 MHz bands, but more costly aircraft, boat, or land vehicle models use dedicated radio control frequencies near 72 MHz to avoid interference by unlicensed uses. The 21st century has seen a move to 2.4 GHz spread spectrum RC control systems. Licensed amateur radio operators use portions of the 6 meter band in North America. Industrial remote control of cranes or railway locomotives use assigned frequencies that vary by area.

Radar applications use relatively high power pulse transmitters and sensitive receivers, so radar is operated on bands not used for other purposes. Most radar bands are in the microwave part of the spectrum, although certain important applications for meteorology make use of powerful transmitters in the UHF band.