Editing Fire-control radar

{{Short description|Narrowly focused radar beam whose reflected signal is used to obtain a missile lock-on}}
[[File:Fc-rate.gif|thumb|200px|<!--Range finder with lightning,-->United States Navy Fire Controlman (FC), USN rating badge]]

A '''fire-control radar''' ('''FCR''') is a [[radar]] that is designed specifically to provide information (mainly target [[azimuth]], [[elevation angle|elevation]], [[ranging|range]] and [[range rate]]) to a [[fire-control system]] in order to direct weapons such that they hit a target. They are sometimes known as '''narrow beam radars''',<ref>{{cite book |title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=9780850451634 |edition=first |publisher=Osprey |year=1973 |page=199}}</ref> '''targeting radars''', '''tracking radars''', or in the UK, '''gun-laying radars'''. If the radar is used to guide a missile, it is often known as a '''target illuminator''' or '''illuminator radar'''.

A typical fire-control radar emits a [[Pencil (optics)|narrow]], intense beam of [[radio wave]]s to ensure accurate tracking information and to minimize the chance of losing track of the target. This makes them less suitable for initial detection of the target, and FCRs are often partnered with a medium-range [[search radar]] to fill this role. In British terminology, these medium-range systems were known as [[tactical control radar]]s.

Most modern radars have a [[track-while-scan]] capability, enabling them to function simultaneously as both fire-control radar and search radar. This works either by having the radar switch between sweeping the search sector and sending directed pulses at the target to be tracked, or by using a [[phased-array]] antenna to generate multiple simultaneous radar beams that both search and track.

==Operational phases==
Fire-control radars operate in three different phases:<ref>{{cite book|url=https://books.google.com/books?id=VopTAAAAMAAJ|pages=101|title=Airborne Radar|author=Donald J. Povejsil|publisher=Boston Technical Publishers|year=1965|isbn=9780598816276 |access-date=2009-02-10}}</ref>

;Designation or vectoring phase: The fire-control radar must be directed to the general location of the target due to the radar's narrow beam width. This phase is also called "lighting up".<ref>{{cite web|url=http://www.wsws.org/en/articles/2016/09/26/jpch-s26.html|title=Japan scrambles fighter to intercept Chinese military aircraft|author=Peter Symonds|publisher=WSWS |date=26 September 2016 |url-status=live |archive-url= https://web.archive.org/web/20231205160621/https://www.wsws.org/en/articles/2016/09/26/jpch-s26.html |archive-date= Dec 5, 2023 }}</ref> It ends when [[Missile lock-on|lock-on]] is acquired.
;Acquisition phase: The fire-control radar switches to the acquisition phase of operation once the radar is in the general vicinity of the target. During this phase, the radar system searches in the designated area in a predetermined search pattern until the target is located or redesignated. This phase terminates when a weapon is launched.
;Tracking phase: The fire-control radar enters into the track phase when the target is located. The radar system locks onto the target during this phase. This phase ends when the target is destroyed.

==Performance==
The performance of a fire-control radar is determined primarily by two factors: radar resolution and atmospheric conditions. Radar resolution is the ability of the radar to differentiate between two targets closely located. The first, and most difficult, is range resolution, finding exactly how far is the target. To do this well, in a basic fire-control radar system, it must send very short pulses. Bearing resolution is typically ensured by using a narrow (one or two degree) beam width. Atmospheric conditions, such as moisture lapse, [[Inversion (meteorology)|temperature inversion]], and dust particles affect radar performance as well. Moisture lapse and temperature inversion often cause ducting, in which RF energy is bent as it passes through hot and cold layers. This can either extend or shorten the [[radar horizon]], depending on which way the RF is bent. Dust particles, as well as water droplets, cause attenuation of the RF energy, resulting in a loss of effective range. In both cases, a lower [[pulse repetition frequency]] makes the radar less susceptible to atmospheric conditions.

==Countermeasures==
Most fire-control radars have unique characteristics, such as radio frequency, pulse duration, pulse frequency and power. These can assist in identifying the radar, and therefore the weapon system it is controlling. This can provide valuable tactical information, like the maximum range of the weapon, or flaws that can be exploited, to combatants that are listening for these signs. During the [[Cold War]] Soviet fire control radars were often [[List of NATO reporting names for equipment|named]] and [[NATO]] pilots would be able to identify the threats present by the radar signals they received.

==Surface based==
One of the first successful fire-control radars, the [[SCR-584 radar|SCR-584]], was used effectively and extensively by the Allies during [[World War II]] for anti-aircraft gun laying. Since World War II, the U.S. Army has used radar for directing anti-aircraft missiles including the [[MIM-23 Hawk]], the [[Nike Missile|Nike]] series and currently the [[MIM-104 Patriot]].

==Ship based==
Examples of fire-control radars currently in use by the [[United States Navy]]:
*Mk 95 — Continuous Wave Illuminator (NATO [[RIM-162 ESSM|Sea sparrow Surface Missile System]])
*Mk 92 — Combined Antenna System (Mk 75 Gun, formerly [[RIM-66 Standard|SM-1 missiles]])
*[[AN/SPG-62]] — Continuous Wave Illuminator ([[Aegis combat system|AEGIS]])
*[[AN/SPQ-9]]B — Pulse Doppler ([[5"/54 caliber Mark 45 gun|Mk 45 lightweight gun]])

==Aircraft based==
After World War II, airborne fire control radars have evolved from the simpler gun and rocket laying [[AN/APG-36]] system used in the [[F-86D]] to the [[active electronically scanned array]]-based [[AN/APG-81]] of the [[F-35 Lightning II]].<ref>{{cite web | url=https://www.northropgrumman.com/what-we-do/air/an-apg-81-active-electronically-scanned-array-aesa-fire-control-radar/ | title=AN/APG-81 Active Electronically Scanned Array (AESA) Fire Control Radar |website=Northrop Grumman |url-status=live |archive-url=https://web.archive.org/web/20240111085210/https://www.northropgrumman.com/what-we-do/air/an-apg-81-active-electronically-scanned-array-aesa-fire-control-radar |archive-date= Jan 11, 2024 }}</ref>

==See also==
*[[Index of aviation articles]]
*[[Radar configurations and types]]
*[[List of radars]]
*[[List of military electronics of the United States]]
*[[Ship gun fire-control system]]

==References==
{{Reflist}}
* US Navy, Fire Controlman, Volume 02—Fire Control Radar Fundamentals (Revised)

==External links==
* [http://www.globalsecurity.org/military/systems/aircraft/systems/an-apg.htm AN/APG Fire Control Systems at GlobalSecurity.org]

{{Naval combat systems}}
{{Military and war}}

[[Category:Military radars]]