{{Short description|American surface-search radar}} {{Infobox radar |image = USS Astoria (CL-90) forward superstructure, 21 October 1944.jpg |caption = SG (at the top of the mast) and [[SK radar|SK-1]] (below and to the left of the SG) radar antennas of {{USS|Astoria|CL-90|6}} |country = United States |designer = {{Plainlist | *[[Raytheon]] *[[MIT Radiation Laboratory]] *[[Naval Research Laboratory]] }} |introdate = 1942 |number = 955 |type =[[Surface-search radar]] |frequency =3 GHz |PRF =775, 800, or 825 |beamwidth = *5.6° (horizontal) *15° (vertical) |pulsewidth= 1.3–2 μs |RPM = 4, 8, or 12 |range = {{cvt|15|nmi|lk=in}} |altitude = |azimuth = <!--X-Yº--> |elevation = <!--X-Yº--> |precision = {{convert|200|yd|m|abbr=on}} |power = 50 kW |other names= }} The '''SG radar''' was a [[US Navy]] [[surface-search radar]] for large warships developed during the [[Second World War]]. The first operational set was installed aboard the [[heavy cruiser]] {{USS|Augusta|CA-31|6}} in April 1942.<ref name=f8>Friedman, p. 148</ref> It was the first Navy radar to use [[S-band]] ([[microwave]]) frequencies <ref name="Gebhard">{{cite book | last = Gebhard | first = Louis A. | title = Evolution of Naval Radio-electronics and Contributions of the Naval Research Laboratory | publisher = US Naval Research Laboratory | date = 1979 | location = | pages = 187 | language = | url = https://books.google.com/books?id=8pOPvqSkcCYC&pg=PA187&dq=sg+radar | archive-url= | archive-date= | doi = | id = | isbn = | mr = | zbl = | jfm =}}</ref> and the first surface-search radar to be equipped with a [[plan position indicator]] (PPI), the ancestor of virtually all modern radar displays.
The radar was developed by [[Raytheon]] under the guidance of the [[MIT Radiation Laboratory]] and [[Naval Research Laboratory]] using the cutting-edge [[cavity magnetron|multicavity magnetron]] technology developed in Britain and brought to the US by the [[Tizard Mission]].<ref name="Gebhard" /> The prototype was tested at sea aboard the [[destroyer]] {{USS|Semmes|DD-189|6}} in May 1941.<ref>Watson, p. 212</ref> It saw extensive use during [[World War 2]], particularly in the Pacific Theater, with about 1000 units produced during the war, and remained in service for about 2 decades.<ref name="Gebhard" /> Designed for installation on destroyers and larger ships to search for low-flying warplanes and surface ships, it achieved greatly improved surface coverage and detection of aircraft compared with previous lower frequency radars.<ref name="Gebhard" /> It also proved a superior navigation aid, making possible the detection of buoys and shoreline at night or bad weather. [[Image:SG Radar Console 1945.jpg|thumb|left|upright=1.4|Operating console. The three large round displays are ''(left to right)'': "A display" of return signal versus time, gyrocompass readout, and PPI (Plan Position Indicator) display]] {{breakafterimages}}
==Notes== {{Reflist}}
==Bibliography== *{{cite book |last1=Brown |first1=Louis |title=A Radar History of World War II: Technical and Military Imperatives |date=1999 |publisher=Institute of Physics Publishing |location=Bristol and Philadelphia |isbn=0-7503-0659-9}} *{{cite book|last=Friedman|first=Norman|title=Naval Radar|year=1981|publisher=Conway Maritime Press |location=London|isbn=0-85177-238-2}} *{{cite book|last=Watson|first=Raymond C. Jr.|title=Radar Origins Worldwide: History of Its Evolution in 13 Nations Through World War II|publisher=Trafford|year=2009 |isbn=978-1-4269-2111-7}}
==Further reading== *{{Cite web|title=US Radar: Operational Characteristics of Radar Classified by Tactical Application|url=https://www.history.navy.mil/content/history/nhhc/research/library/online-reading-room/title-list-alphabetically/u/operational-characteristics-of-radar-classified-by-tactical-application.html|access-date=2022-02-18|publisher=Naval History and Heritage Command|language=en-US}}
[[Category:Naval radars]] [[Category:World War II radars]] [[Category:Military equipment introduced from 1940 to 1944]] [[Category:Military radars of the United States]] [[Category:MIT Radiation Laboratory radars]]