Fire-control radar
Encyclopedia
A fire-control radar is a radar
which is designed specifically to provide information (mainly target azimuth, elevation, range and velocity) to a fire-control system
in order to calculate a firing solution (i.e. information on how to direct weapons such that they hit the target(s)). Such radars typically emit a narrow, intense beam of radio wave
s to ensure accurate tracking information and to minimise the chance of losing track of the target. Some modern radars have a track-while-scan capability enabling it to function simultaneously as a fire-control radar and a 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 two (or more) discrete radar beams and dividing them between both tasks.
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 ends when 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.
, depending on which way the RF is bent. Dust particles, as well as water droplets, cause attenuation of the RF energy, translating into a loss of effective range. In both cases, a lower pulse repetition frequency makes the radar less susceptible to atmospheric conditions.
Soviet fire control radars were often named and NATO pilots would be able to identify the threats present by the radar signals they received.
, was used effectively and extensively by the Allies during World War II
for anti-aircraft gun laying. Since WWII, the U.S. Army has used radar for directing anti-aircraft missiles including the MIM-23 Hawk
, the Nike series and currently the MIM-104 Patriot
.
:
based AN/APG-81 of the F-35
.
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
which is designed specifically to provide information (mainly target azimuth, elevation, range and velocity) to a fire-control system
Fire-control system
A fire-control system is a number of components working together, usually a gun data computer, a director, and radar, which is designed to assist a weapon system in hitting its target. It performs the same task as a human gunner firing a weapon, but attempts to do so faster and more...
in order to calculate a firing solution (i.e. information on how to direct weapons such that they hit the target(s)). Such radars typically emit a narrow, intense beam of radio wave
Radio Wave
Radio Wave may refer to:*Radio frequency*Radio Wave 96.5, a radio station in Blackpool, UK...
s to ensure accurate tracking information and to minimise the chance of losing track of the target. Some modern radars have a track-while-scan capability enabling it to function simultaneously as a fire-control radar and a 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 two (or more) discrete radar beams and dividing them between both tasks.
Operational phases
Fire-control radars operate in three different phases: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 ends when lock-on
Missile lock-on
Missile lock-on refers to a scenario where the guidance system for a missile can accurately track a target, and a fire-control system can calculate the required flightpath for the missile to hit the target...
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 by 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 problematic, is gaining high range resolution. To do this in a basic fire-control radar system, it must operate at a high pulse repetition frequency and have a high receiver sensitivity. Bearing resolution is typically ensured by using a narrow (one or two degree) beam width. Atmospheric conditions, such as moisture lapse, 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 reduce the radar horizonRadar horizon
The radar Horizon is a critical area of performance for aircraft detection systems that is defined by the distance at which the radar beam raise enough above the Earth surface to make detection of a target at low level impossible. It is associated with the low elevation region of performance and...
, depending on which way the RF is bent. Dust particles, as well as water droplets, cause attenuation of the RF energy, translating into 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 warCold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
Soviet fire control radars were often 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-584SCR-584 radar
The SCR-584 was a microwave radar developed by the MIT Radiation Laboratory during World War II. It replaced the earlier and much more complex SCR-268 as the US Army's primary anti-aircraft gun laying system as quickly as they could be produced...
, was used effectively and extensively by the Allies during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
for anti-aircraft gun laying. Since WWII, the U.S. Army has used radar for directing anti-aircraft missiles including the MIM-23 Hawk
MIM-23 Hawk
The Raytheon MIM-23 Hawk is a U.S. medium range surface-to-air missile. The Hawk was initially designed to destroy aircraft and was later adapted to destroy other missiles in flight. The missile entered service in 1960, and a program of extensive upgrades has kept it from becoming obsolete. It was...
, the Nike series and currently the MIM-104 Patriot
MIM-104 Patriot
The MIM-104 Patriot is a surface-to-air missile system, the primary of its kind used by the United States Army and several allied nations. It is manufactured by the Raytheon Company of the United States. The Patriot System replaced the Nike Hercules system as the U.S. Army's primary High to Medium...
.
Ship based
Examples of fire-control radars currently in use by the United States NavyUnited States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
:
- Mk 95 — Continuous Wave Illuminator (NATO Seasparrow Surface Missile System)
- Mk 92 — Combined Antenna System (Mk 75 Gun, formerly SM-1 missilesRIM-66 StandardThe RIM-66 Standard MR is a medium range surface-to-air missile originally developed for the United States Navy . The SM-1 was developed as a replacement for the RIM-2 Terrier and RIM-24 Tartar that were deployed in the 1950s on a variety of USN ships...
) - AN/SPG-62 — Continuous Wave Illuminator (AEGISAegis combat systemThe Aegis Combat System is an integrated naval weapons system developed by the Missile and Surface Radar Division of RCA, and now produced by Lockheed Martin...
) - AN/SPQ-9AN/SPQ-9AN/SPQ-9A, , is a United States Navy multi-purpose surface search & fire control radar used with the Mk-86 gun fire-control system . It is a two dimensional radar, meaning it provides only range and bearing but not elevation...
B — Pulse Doppler (Mk 45 lightweight gun)
Aircraft based
After WWII, 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 ArrayActive Electronically Scanned Array
An Active Electronically Scanned Array , also known as active phased array radar is a type of phased array radar whose transmitter and receiver functions are composed of numerous small solid-state transmit/receive modules . AESAs aim their "beam" by broadcasting radio energy that interfere...
based AN/APG-81 of the F-35
F-35 Lightning II
The Lockheed Martin F-35 Lightning II is a family of single-seat, single-engine, fifth generation multirole fighters under development to perform ground attack, reconnaissance, and air defense missions with stealth capability...
.