Radio spectrum
Template:Short description Template:About Template:MWband
The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 KHz 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).<ref>ITU Radio Regulations – Article 1, Definitions of Radio Services, Article 1.2 Administration: Any governmental department or service responsible for discharging the obligations undertaken in the Constitution of the International Telecommunication Union, in the Convention of the International Telecommunication Union and in the Administrative Regulations (CS 1002)</ref>
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).<ref>International Telecommunication Union's Radio Regulations, Edition of 2020.</ref> 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).<ref>Template:Cite book</ref> 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.
Limits
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.<ref name="RadioRegulations1">Radio waves are defined by the ITU as: "electromagnetic waves of frequencies arbitrarily lower than 3000 GHz, propagated in space without artificial guide", Template:Cite book</ref> Radio waves are defined by the ITU as: "electromagnetic waves of frequencies arbitrarily lower than 3000 GHz, propagated in space without artificial guide".<ref>Template:Cite book</ref> 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.<ref name="RadioRegulations1"/> but spectroscopic scientists consider these frequencies part of the far infrared and mid infrared bands.
Because it is a fixed resource, the practical limits and basic physical considerations of the radio spectrum, the frequencies which are useful for radio communication, are determined by technological limitations which are impossible to overcome.<ref name="Gosling">Template:Cite book</ref> 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.<ref name="Gosling"/> The lowest frequencies used for radio communication are limited by the increasing size of transmitting antennas required.<ref name="Gosling" /> The size of antenna required to radiate radio power efficiently increases in proportion to wavelength or inversely with frequency. Below about 10 kHz (a wavelength of 30 km), elevated wire antennas kilometers in diameter are required, so very few radio systems use frequencies below this. A second limit is the decreasing bandwidth available at low frequencies, which limits the data rate that can be transmitted.<ref name="Gosling" /> Below about 30 kHz, audio modulation is impractical and only slow baud rate data communication is used. The lowest frequencies that have been used for radio communication are around 80 Hz, in ELF submarine communications systems built by a few nations' navies to communicate with their submerged submarines hundreds of meters underwater. These employ huge ground dipole antennas 20–60 km long excited by megawatts of transmitter power, and transmit data at an extremely slow rate of about 1 bit per minute (17 millibits per second, or about 5 minutes per character).
The highest frequencies useful for radio communication are limited by the absorption of microwave energy by the atmosphere.<ref name="Gosling" /> As frequency increases above 30 GHz (the beginning of the millimeter wave band), atmospheric gases absorb increasing amounts of power, so the power in a beam of radio waves decreases exponentially with distance from the transmitting antenna. At 30 GHz, useful communication is limited to about 1 km, but as frequency increases the range at which the waves can be received decreases. In the terahertz band above 300 GHz, the radio waves are attenuated to zero within a few meters due to the absorption of electromagnetic radiation by the atmosphere (mainly due to ozone, water vapor and carbon dioxide), which is so great that it is essentially opaque to electromagnetic emissions, until it becomes transparent again near the near-infrared and optical window frequency ranges.<ref name="Coutaz">Template:Cite book</ref><ref name="Siegel">Template:Cite web</ref>
Bands
A radio band Template:Anchor 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.
Band plan
For each radio band, the ITU has a band plan (or frequency plan) which dictates how it is to be used and shared, to avoid interference and to set protocol for the compatibility of transmitters and receivers.<ref>See detail of bands: [1] Template:Webarchive</ref>
Each frequency plan defines the frequency range to be included, how channels are to be defined, and what will be carried on those channels. Typical definitions set forth in a frequency plan are:
- numbering scheme – which channel numbers or letters (if any) will be assigned
- center frequencies – how far apart the carrier wave for each channel will be
- bandwidth and/or deviation – how wide each channel will be
- spectral mask – how extraneous signals will be attenuated by frequency
- modulation – what type will be used or are permissible
- content – what types of information are allowed, such as audio or video, analog or digital
- licensing – what the procedure will be to obtain a broadcast license
ITU
The actual authorized frequency bands are defined by the ITU<ref>Frequency Plans</ref> and the local regulating agencies like the US Federal Communications Commission (FCC) <ref>For the authorized frequency bands for amateur radio use see: Authorized frequency bands</ref> and voluntary best practices help avoid interference.<ref>US ARRL Amateur Radio Bands and power limits Graphical Frequency Allocations</ref>
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".<ref name="ITU2020">ITU Radio Regulations, Volume 1, Article 2; Edition of 2020. Available online at Template:Cite web</ref>
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.<ref>Template:Cite journal</ref>
The band name "tremendously low frequency" (TLF) has been used for frequency and wavelength of 1–3 Hz | 300,000–100,000 km (1000 Mm),<ref name="Duncan 2021 235–247">Template:Cite book</ref> but the term has not been defined by the ITU.<ref>Template:Cite web</ref>
IEEE radar bandsTemplate:Anchor
Frequency bands in the microwave range are designated by letters. This convention began around World War II with military designations for frequencies used in radar, which was the first application of microwaves. There are several incompatible naming systems for microwave bands, and even within a given system the exact frequency range designated by a letter may vary somewhat between different application areas. One widely used standard is the IEEE radar bands established by the US Institute of Electrical and Electronics Engineers.
| Band designation |
Frequency range | Explanation of meaning of letters |
|---|---|---|
| HF | 0.003 to 0.03 GHz | High frequencyTemplate:Refn |
| VHF | 0.03 to 0.3 GHz | Very high frequency<ref name=ieee_names /> |
| UHF | 0.3 to 1 GHz | Ultra-high frequency<ref name=ieee_names /> |
| L | 1 to 2 GHz | Long wave |
| S | 2 to 4 GHz | Short wave |
| C | 4 to 8 GHz | Compromise between S and X |
| X | 8 to 12 GHz | Used in World War II for fire control, X for cross (as in crosshair). Exotic.<ref name="Friedman2006">Template:Cite book</ref> |
| Ku | 12 to 18 GHz | Template:Lang-under |
| K | 18 to 27 GHz | Template:Langx (short) |
| Ka | 27 to 40 GHz | Template:Lang-above |
| V | 40 to 75 GHz | |
| W | 75 to 110 GHz | W follows V in the alphabet<ref>Template:Cite journal</ref> |
| mm or G | 110 to 300 GHzTemplate:Refn | Millimeter<ref name=ieee /> |
EU, NATO, US ECM frequency designations
| NATO letter band designation<ref name="BelovSmolskiy2012">Template:Cite book</ref><ref name="Friedman2006"/><ref>NATO Allied Radio Frequency Agency (ARFA) HANDBOOK – VOLUME I; PART IV – APPENDICES, ... G-2, ... NOMENCLATURE OF THE FREQUENCY AND WAVELENGTH BANDS USED IN RADIOCOMMUNCATION.</ref> | Broadcasting band designation | ||||||
|---|---|---|---|---|---|---|---|
| 1978<ref>AFR 55-44/AR 105-86/OPNAVINST 3430.9A/MCO 3430.1, 27 October 1964 superseded by AFR 55-44/AR 105-86/OPNAVINST 3430.1A/MCO 3430.1A, 6 December 1978: Performing Electronic Countermeasures in the United States and Canada, Attachment 1,ECM Frequency Authorizations.
PDF[2]</ref>-Present nomenclature!! bgcolor="#CCCCCC" | |
Pre-1978 nomenclature | ||||||
| Band | Frequency (MHz) | Band | Frequency (MHz) | ||||
| A | 0 – 250 | I | 100 – 150 | Band I 47 – 68 MHz (TV) | |||
| Band II 87.5 – 108 MHz (FM) | |||||||
| G | 150 – 225 | Band III 174 – 230 MHz (TV) | |||||
| B | 250 – 500 | P | 225 – 390 | ||||
| C | 500 – 1 000 | L | 390 – 1 550 | Band IV 470 – 582 MHz (TV) | |||
| Band V 582 – 862 MHz (TV) | |||||||
| D | 1 000 – 2 000 | S | 1 550 – 3 900 | ||||
| E | 2 000 – 3 000 | ||||||
| F | 3 000 – 4 000 | ||||||
| G | 4 000 – 6 000 | C | 3 900 – 6 200 | ||||
| H | 6 000 – 8 000 | X | 6 200 – 10 900 | ||||
| I | 8 000 – 10 000 | ||||||
| J | 10 000 – 20 000 | Ku | 10 900 – 20 000 | ||||
| K | 20 000 – 40 000 | Ka | 20 000 – 36 000 | ||||
| L | 40 000 – 60 000 | Q | 36 000 – 46 000 | ||||
| V | 46 000 – 56 000 | ||||||
| M | 60 000 – 100 000 | W | 56 000 – 100 000 | ||||
| US Military/SACLANT | |||||||
| N | 100 000 – 200 000 | ||||||
| O | 100 000 – 200 000 | ||||||
Waveguide frequency bands
| Band | Frequency range <ref>Template:Cite web</ref> |
|---|---|
| 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 |
| Template:Ku band | 12.4 to 18.0 GHz |
| K band | 18.0 to 26.5 GHz |
| Template:Ka band | 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 |
Comparison of radio band designation standards
A frequency of 1–3 Hz<ref name="Duncan 2021 235–247"/> has been called TLF but the term has not been defined by the ITU.<ref>Template:Cite web</ref>
| Frequency | IEEE<ref name=ieee /> | EU, NATO, US ECM |
ITU | ||
|---|---|---|---|---|---|
| no. | abbr. | ||||
| A | |||||
| 3 Hz | 1 | ELF | |||
| 30 Hz | 2 | SLF | |||
| 300 Hz | 3 | ULF | |||
| 3 kHz | 4 | VLF | |||
| 30 kHz | 5 | LF | |||
| 300 kHz | 6 | MF | |||
| 3 MHz | HF | 7 | HF | ||
| 30 MHz | VHF | 8 | VHF | ||
| 250 MHz | B | ||||
| 300 MHz | UHF | 9 | UHF | ||
| 500 MHz | C | ||||
| 1 GHz | L | D | |||
| 2 GHz | S | E | |||
| 3 GHz | F | 10 | SHF | ||
| 4 GHz | C | G | |||
| 6 GHz | H | ||||
| 8 GHz | X | I | |||
| 10 GHz | J | ||||
| 12 GHz | Ku | ||||
| 18 GHz | K | ||||
| 20 GHz | K | ||||
| 27 GHz | Ka | ||||
| 30 GHz | 11 | EHF | |||
| 40 GHz | V | L | |||
| 60 GHz | M | ||||
| 75 GHz | W | ||||
| 100 GHz | |||||
| 110 GHz | mm | ||||
| 300 GHz | 12 | THF | |||
| 3 THz | |||||
Applications
Template:See alsoRadio has many practical applications, which include broadcasting, voice communication, data communication, radar, radiolocation, medical treatments, and remote control.
See also
Notes
References
- ITU-R Recommendation V.431: Nomenclature of the frequency and wavelength bands used in telecommunications. International Telecommunication Union, Geneva.
- IEEE Standard 521-2002: Standard Letter Designations for Radar-Frequency Bands
- AFR 55-44/AR 105-86/OPNAVINST 3430.9A/MCO 3430.1, 27 October 1964 superseded by AFR 55-44/AR 105-86/OPNAVINST 3430.1A/MCO 3430.1A, 6 December 1978: Performing Electronic Countermeasures in the United States and Canada, Attachment 1,ECM Frequency Authorizations.
External links
- UnwantedEmissions.com A reference to radio spectrum allocations.
- "Radio spectrum: a vital resource in a wireless world" European Commission policy.