View source for S band

{{Short description|Frequency range}}
{{Use dmy dates|date=June 2021}}
{{More citations needed|date=June 2021}}
{{MWband
| name = IEEE S band
| freq = 2 – 4 [[Hertz|GHz]]
| wave = 15 – 7.5 [[Meter|cm]]
| bands = {{startplainlist|class=nowrap}}
* [[E band (NATO)|E]]{{\}}[[F band (NATO)|F band]]s (NATO)
* [[Ultra high frequency|UHF]]{{\}}[[Super high frequency|SHF]] (ITU)
{{endplainlist}}
}}

The '''S band''' is a designation by the [[Institute of Electrical and Electronics Engineers]] (IEEE) for a part of the [[microwave]] [[radio band|band]] of the [[electromagnetic spectrum]] covering [[frequency|frequencies]] from 2 to 4&nbsp;[[gigahertz]] (GHz). Thus it crosses the conventional boundary between the [[Ultra high frequency|UHF]] and [[Super high frequency|SHF]] bands at 3.0&nbsp;GHz. The S band is used by [[airport surveillance radar]] for [[air traffic control]], [[weather radar]], surface ship [[radar]], and some [[communications satellite]]s, particularly [[Tracking and Data Relay Satellite System|satellites used]] by [[NASA]] to communicate with the [[Space Shuttle]] and the [[International Space Station]]. The 10&nbsp;cm [[radar]] short-band ranges roughly from 1.55 to 5.2&nbsp;GHz. India's regional satellite navigation network ([[IRNSS]]) broadcasts on 2.483778 to 2.500278&nbsp;GHz.<ref>{{cite web |url=https://www.isro.gov.in/sites/default/files/irnss_sps_icd_version1.1-2017.pdf |title=Indian Regional Navigational Satellite System Signal In Space Interface Control Document for Standard Positioning Service |date=August 2017 |website=[[Indian Space Research Organization]] |access-date=8 February 2019 |archive-date=12 November 2020 |archive-url=https://web.archive.org/web/20201112023003/https://www.isro.gov.in/sites/default/files/irnss_sps_icd_version1.1-2017.pdf |url-status=dead }}</ref>

The S band also contains the 2.4–2.483&nbsp;GHz [[ISM band]], widely used for low power unlicensed microwave devices such as [[cordless phone]]s, wireless headphones ([[Bluetooth]]), [[garage door opener]]s, [[keyless entry|keyless vehicle locks]], [[baby monitor]]s as well as for medical [[diathermy]] machines and [[microwave oven]]s (typically at 2.495&nbsp;GHz).  One of its largest uses is 2.4&nbsp;GHz [[IEEE 802.11]] [[Wi-Fi]] wireless networks, allowing smartphones, laptops, printers and TVs to connect to the internet without cables. 
[[Image:Wireless network.jpg|thumb|One of the largest uses is for [[Wi-Fi]] networks, allowing devices like [[laptop]]s ''(left)'' to connect to the internet through a [[Router (computing)|router]] ''(right)'']]

==Wi-Fi==
The largest use of this band is by [[Wi-Fi]] networks; the [[IEEE 802.11|IEEE 802.11b]] and [[IEEE 802.11|802.11g]] standards use the 2.4 GHz section of the S band. These are the most widely used computer networks in the world, used globally in [[small office/home office|home and small office networks]] to link [[desktop computer|desktop]] and [[laptop]] computers, [[tablet computer]]s, [[smartphone]]s, [[smart TV]]s, [[Printer (computing)|printers]], and [[smart speaker]]s together and to a [[wireless router]] to connect them to the Internet, and in [[wireless access point]]s in public places like coffee shops, hotels, libraries and airports to provide public Internet access for mobile devices.

==Mobile services==

Mobile services are operated in the 2.3&nbsp;GHz to 2.6&nbsp;GHz range, specifically between the 2300–2400&nbsp;MHz band and the 2500–2690&nbsp;MHz band. Spectrum in the 3.55–3.7 GHz band has been auctioned off in the United States to be used for [[CBRS]] services and spectrum between 3.45–3.55&nbsp;GHz and 3.7–3.98&nbsp;GHz has been auctioned off by the FCC for 5G although this spectrum is referred to as [[C band (IEEE)|C Band]] by the agency.

==Satellite communications==
[[File:MILA 9-meter S-band tracking antenna (KSC-2011-6004).jpg|thumb|S-band tracking antenna at [[Kennedy Space Center]]]]
[[File:Satellite Dish of Indovision.jpg|thumb|A Indovision (now [[MNC Vision]]) 80cm S-band satellite dish]]

In the United States, the [[Federal Communications Commission|FCC]] approved satellite-based [[Digital Audio Radio Service]] (DARS) [[Radio broadcasting|broadcasting]] in the S band from 2.31 to 2.36&nbsp;GHz in 1995,<ref>{{cite web |url=https://www.radioworld.com/misc-1/today-in-radio-history |title=Today in Radio History (January 12) |date=January 26, 2015 |website=[[Radio World]] |access-date=11 April 2020}}</ref> used by [[Sirius XM Radio]]. More recently, it has approved portions of the S band between 2.0 and 2.2&nbsp;GHz for the creation of Mobile Satellite Service (MSS) networks in connection with Ancillary Terrestrial Components (ATC). There have been a number of companies attempting to deploy such networks, including ICO Satellite Management (now [[Pendrell Corporation]]) and [[TerreStar]] (defunct).

The 2.6&nbsp;GHz range is used for [[China Multimedia Mobile Broadcasting]], a [[satellite radio]] and [[mobile TV]] standard which, as with proprietary systems in the United States, is incompatible with the [[open standard]]s used in the rest of the world.

In May 2009, [[Inmarsat]] and [[Solaris Mobile]] (a joint venture between [[Eutelsat Communications|Eutelsat]] and [[SES (company)|SES]] ([[EchoStar Mobile]])) were each awarded a 2×15&nbsp;MHz portion of the S band by the [[European Commission]].<ref>{{cite web |url=http://europa.eu/rapid/pressReleasesAction.do?reference=IP/09/770 |title=Press release - European Commission paves the way for European mobile satellite services |date=14 May 2009 |website=[[Europa.eu]] |access-date=1 April 2018}}</ref> The two companies are allowed two years to start providing pan-European MSS services for 18 years. Allocated frequencies are 1.98 to 2.01&nbsp;GHz for Earth to space communications, and from 2.17 to 2.2&nbsp;GHz for space to Earth communications.<ref>{{cite web |url=http://www.erodocdb.dk/docs/doc98/Official/Pdf/6262008EC.pdf |title=Decision No 626/2008/EC of the European Parliament and of the Council of 30 June 2008 on the selection and authorisation of systems providing mobile satellite services (MSS) |website=[[European Communications Office]] |access-date=1 April 2018 |url-status=dead |archive-url=https://web.archive.org/web/20170630060054/http://www.erodocdb.dk/docs/doc98/Official/Pdf/6262008EC.pdf |archive-date=30 June 2017}}</ref> The Eutelsat [[W series (satellites)|W2A]] satellite was launched in April 2009 and is located at 10° East.

In [[Indonesia]], S band is used by [[MNC Vision]] for [[Direct broadcast satellite|Direct-to-Home satellite]] television (unlike similar services in most countries, which use [[Ku band|K<sub>u</sub> band]]). The frequency allocated for this service is 2.52-2.67&nbsp;GHz (LOF 1.570&nbsp;GHz).

[[IndoStar-1]] was the world's first commercial communications satellite to use S-band frequencies for broadcast, which efficiently penetrate the atmosphere and provide high-quality transmissions to small-diameter 80&nbsp;cm antennas in regions that experience heavy rainfall such as Indonesia. A similar Ku- or C-band reception performance requires greater transmission power or much larger dish to penetrate the moist atmosphere.

=== Deep space communications ===
[[File:AS12-47-6988 (21471781868).jpg|thumb|[[Apollo 12]] Erectable S-Band Antenna]]
Many NASA spacecraft (near Earth and interplanetary) can communicate in the S-band, often using the [[Deep Space Network]].  For example, the [[James Webb Space Telescope]], launched in 2021, utilizes 2 GHz S-band to enable 40 kbps real time telemetry<ref>{{Cite web|url=https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-spacecraft-bus/jwst-communications-subsystem#:~:text=JWST's%20communications%20subsystem%20is%20the,rate%20telemetry%20downlink%2C%20and%20ranging.|title = JWST Communications Subsystem - JWST User Documentation}}</ref> from near the Sun–Earth [[L2 point]].

==Other uses==
{{main|Citizens Broadband Radio Service}}

[[Microwave oven]]s operate at 2495 or 2450&nbsp;MHz in the ISM band [[IEEE 802.16]]a. Some digital cordless telephones operate in this band too. 802.16e standards use a part of the frequency range of S band; under [[WiMAX]] standards. Most vendors are manufacturing equipment in the range of 3.5&nbsp;GHz. The exact frequency range allocated for this type of use varies between countries.

In North America, {{nowrap|2.4&ndash;2.483 GHz}} is an [[ISM band]] used for [[unlicensed spectrum]] devices such as [[cordless phone]]s, [[wireless headphone]]s, and [[video sender]]s, among other [[consumer electronics]] uses, including [[Bluetooth]] which operates between 2.402&nbsp;GHz and 2.480&nbsp;GHz.

[[Amateur radio]] and [[amateur satellite]] operators have two S-band allocations, [[13-centimeter band|13 cm]] (2.4&nbsp;GHz) and [[9-centimeter band|9 cm]] (3.4&nbsp;GHz). [[Amateur television]] repeaters also operate in these bands.

Airport surveillance radars typically operate in the 2700&ndash;2900&nbsp;MHz range.

Particle accelerators may be powered by S-band RF sources. The frequencies are then standardized at 2.998&nbsp;GHz corresponding to a wavelength of 100&nbsp;mm (Europe) or 2.856&nbsp;GHz (US).<ref>{{cite web |url=https://www.jlab.org/conferences/FLS2012/talks/Thur/isu_jlab39_fls2012_57_final.PDF |title=Performance Comparison of S-band, C-band, and X-band RF Linac based XFELs |first=Yujong |last=Kim |date=2012 |website=[[Thomas Jefferson National Accelerator Facility]]}}</ref>

The National [[NEXRAD]] Radar network operates with S-band frequencies. Before implementation of this system, [[C band (IEEE)|C-band]] frequencies were commonly used for weather surveillance.

In the United States, the 3.55 to 3.7&nbsp;GHz band is becoming shared spectrum under rules adopted by the [[Federal Communications Commission]] in April 2015 as a result of the [[National Broadband Plan (United States)]]. The biggest user of CBRS ([[Citizens Broadband Radio Service]]) spectrum is the [[United States Navy]].<ref>{{cite journal |title=CBRS Spectrum Could Open Windows of Opportunity for Cable Ops |last=Baumgartner |first=Jeff |journal=[[Broadcasting & Cable]] |date=October 23, 2017 |page=18}}</ref><ref>{{cite news |url=https://www.networkworld.com/article/961402/faq-what-in-the-wireless-world-is-cbrs.html |title=FAQ: What in the wireless world is CBRS? |last=Brown |first=Bob |work=Network World |date=March 14, 2017 |access-date=January 11, 2018}}</ref> Cable companies are planning to use the band for [[wireless broadband]] in rural areas, with [[Charter Communications]] beginning tests of the service in January 2018.<ref>{{cite journal |title=Charter Puts Wireless Broadband to the Test |last=Baumgartner |first=Jeff |journal=Broadcasting & Cable |date=February 5, 2018 |page=22}}</ref>

The band is also used as a transmit intermediate frequency in satellite communications as a replacement for [[L band]] where a single/shared coaxial connection is used between the modem/IDU and antenna/ODU for both the transmit and receive signals. This is to prevent interference between the transmit and receive signals which would otherwise not occur on a dual coaxial setup where the transmit and receive signals are separate and both can use the whole L-band frequency range. In a single coaxial connection using S-Band to "frequency shift" the transmit signal away from L band, a multiplier such as 10, is usually applied to form the SHF frequency. For example, the modem would transmit at 2.815&nbsp;GHz IF (S Band) to the ODU and then the ODU up-converts this signal to 28.15&nbsp;GHz SHF ([[Ka band|Ka Band]]) towards the satellite.<ref>{{cite web |url=https://www.newtec.eu/frontend/files/leaflet/newtec-mdm2210-on-the-newtec-dialog-platform.pdf |title=Datasheet for Newtec MDM2210 Terminal with S-Band Transmit Frequency |date=May 2018 |website=Newtec |url-status=dead |archive-url=https://web.archive.org/web/20180824034255/https://www.newtec.eu/frontend/files/leaflet/newtec-mdm2210-on-the-newtec-dialog-platform.pdf |archive-date=August 24, 2018}}</ref><ref>{{cite web |url=http://www.accesointernetsatelital.com/downloads/ToowayKav4.6-EN.pdf |title=Full Manual for Tooway™ Satellite Terminal with S-Band Transmit Frequency |page=28 |date=October 2009 |website=Tooway}}</ref>

==See also==
* [[List of 2.4 GHz radio use|Electromagnetic interference at 2.4 GHz]]
* [[ISM band]]
* [[Unified S-band]], an S-band communication system used in the [[Apollo program]] of crewed spaceflight

==References==
{{reflist}}

==External links==
*{{cite web |url=http://www.terrestar.com/ |title=TerreStar Networks |website=TerreStar Corporation |url-status=dead |archive-url=https://web.archive.org/web/20100119014725/http://www.terrestar.com/ |archive-date=2010-01-19}}
*{{cite web |url=http://www.zarya.info/Frequencies/FrequenciesSband.php |title=Satellite Radio Frequencies: Transmissions at S-band |first=Robert |last=Christy |website=Zarya.info |url-status=live |archive-url=https://web.archive.org/web/20120813230620/http://www.zarya.info/Frequencies/FrequenciesSband.php |archive-date=2012-08-13}}
*{{cite web |url=http://www.tsgc.utexas.edu/archive/characterizations/pioneer10.html |title=Pioneer 10 & 11 |first=John P. |last=Esteves |date=1 August 2004 |website=Texas Space Grant Consortium |url-status=dead |archive-url=https://web.archive.org/web/20050301210244/http://www.tsgc.utexas.edu/archive/characterizations/pioneer10.html |archive-date=2005-03-01}}

{{Radio spectrum}}
{{EMSpectrum}}
{{Audio broadcasting}}

{{DEFAULTSORT:S Band}}
[[Category:Microwave bands]]
[[Category:Satellite broadcasting]]
[[Category:Telecommunications equipment]]