Semi-active radar homing, or SARH, is a common type of missile guidance system, perhaps the most common type for longer range air-to-air and surface-to-air missile systems. The name refers to the fact that the missile itself is only a passive detector of a radar signal – provided by an external ("offboard") source – as it reflects off the target. A guided bomb strikes an underground facility Missile guidance technologies of missile systems use a variety of methods to guide a missile to its intended target. ... A US Navy VF-103 Jolly Rogers F-14 Tomcat fighter launches an AIM-54 Phoenix long-range air-to-air missile. ... Akash Missile Firing French Air Force Crotale battery Bendix Rim-8 Talos surface to air missile of the US Navy A surface-to-air missile (SAM) is a missile designed to be launched from the ground to destroy aircraft. ...

NATO brevity code for a semi-active radar homing missile launch is Fox One.

Concept

The basic concept of SARH is that almost all detection and tracking systems consist of a radar system, so duplicating this hardware on the missile itself is wasted. In addition, the resolution of a radar is strongly related to the physical size of the antenna, in the small nose cone of a missile there isn't enough room to provide the sort of accuracy needed for guidance. Instead the larger radar dish on the ground or launch aircraft will provide the needed signal and tracking logic, and the missile simply has to listen to the target reflected signal and point itself in the right direction. Additionally, the missile will listen rearward to the the launch platform's transmitted signal as a reference, enabling it to avoid some kinds of radar jamming distractions offered by the target. This long range Radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. Radar is a system that uses radio waves to determine and map the location, direction, and/or speed... Angular resolution describes the resolving power of any optical device such as a telescope, a microscope, a camera, or an eye. ...

Contrast this with beam riding systems, in which the radar is pointed at the target and the missile keeps itself centered in the beam by listening to the signal at the rear of the missile body. In the SARH system the missile listens for the reflected signal at the nose, and is still responsible for providing some sort of "lead" guidance. The advantages are twofold. One is that a radar signal is "fan shaped" growing larger, and therefore less accurate, with distance. This means that the beam riding system is not terribly accurate at long ranges, while SARH is largely independent of range and grows more accurate as it approaches the target—the "source" of the signal it listens for. Another addition is that a beam riding system must accurately track the target at high speeds, typically requiring one radar for tracking and another "tighter" beam for guidance. The SARH system needs only one radar set to a wider pattern. Beam-riding guidance leads a missile to its target by means of radar or a laser beam. ...

Continuous-wave radar

Modern SARH systems use continuous-wave (CW) radar for guidance. Even though most modern fighter radars are pulse Doppler sets, most have a CW function to guide radar missiles. A few Soviet aircraft, such as some versions of the MiG-23 and MiG-27, used an auxiliary guidance pod or aerial to provide a CW signal. Vympel R-33 AA missile for MiG-31 interceptor uses SARH as the main type of guidance (with supplement of inertial guidance on initial stage). A continuous wave (CW) (or Continous Waveform) is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. ... Soviet redirects here. ... Mikoyan-Gurevich MiG-23 (Flogger). ... The Mikoyan-Gurevich MiG-27 (NATO reporting name Flogger) is a ground attack aircraft, originally built by the Mikoyan-Gurevich Design Bureau in the Soviet Union and later licence-produced in India by Hindustan Aeronautics as the Bahadur (Valiant). It is based on the MiG-23 fighter aircraft, but optimized... The Vympel R-33 (NATO reporting name AA-9 Amos) was the most advanced long-range air-to-air missile developed by the Soviet Union. ... Mikoyan MiG-31 Foxhound The Mikoyan MiG-31 (NATO reporting name Foxhound) is a high-speed interceptor developed to replace the MiG-25. ...

SARH missiles require the tracking radar to lock on to the target and then illuminate it for the entire duration of the missile's flight. This could leave the launch aircraft vulnerable to counter attack, as well giving the target's electronic warning systems time to detect the attack and engage countermeasures. Because most SARH missiles require guidance during their entire flight, only one target per radar emitter can be engaged at a time.

Electronic counter-countermeasure (ECCM)

Recent-generation SARH weapons have superior electronic counter-countermeasure (ECCM) capability, but the system still has fundamental limitations. Some newer missiles, such as the Standard SM-2 incorporate terminal semi-active radar homing (TSARH). TSARH missiles use inertial guidance for most of their flight, only activating their SARH system for the final attack. This can keep the target from realising it is under attack until shortly before the missile strikes. Since the missile only requires guidance during the terminal phase, each radar emitter can be used to engage more targets. Some of these weapons, like the SM-2, allow the firing aircraft to update the missile with mid-course updates via datalink. Electronic counter-countermeasures (ECCM) describes a variety of practices which attempt to reduce or eliminate the effect of Electronic countermeasures ( ECM) on sensors aboard vehicles, ships and aircraft and especially seekers on weapons such as missiles. ... The Standard Missile is a type of surface-to-air missile (SAM) originally developed for the United States Navy. ... An inertial navigation system measures the position and altitude of a vehicle by measuring the accelerations and rotations applied to the systems inertial frame. ... In telecommunication, the term data link has the following meanings: The means of connecting one location to another for the purpose of transmitting and receiving data. ...

Combat record

The combat record of SARH missiles was unimpressive during the Vietnam War. USAF and US Navy fighters armed with AIM-7 Sparrow attained a success rate of barely 10%, which tended to amplify the effect of deleting the gun on most F-4 Phantoms, which carried 4 Sparrows. Some of the failures were attributable to mechanical failure of 1960s era electronics which could be disturbed by pulling a cart over uneven pavement, or pilot error; the intrinsic accuracy of these weapons was relatively low relative to Sidewinder and guns. However, since Desert Storm, most F-15 Eagle combat victories have been scored with the Sparrow at BVR ranges. Also notable is the combat victory of an Israeli Eagle on one fast, high-flying MiG-25 Foxbat. Combatants Republic of Vietnam United States Republic of Korea Thailand Australia New Zealand The Philippines National Front for the Liberation of South Vietnam Democratic Republic of Vietnam People’s Republic of China Democratic Peoples Republic of Korea Strength US 1,000,000 South Korea 300,000 Australia 48,000... Seal of the Air Force. ... The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ... A RIM-7 Sea Sparrow being launched from the USS Essex (LHD-2). ... The F-4 Phantom II (simply F-4 Phantom after 1990) is a two-place (tandem), supersonic, long-range, all-weather fighter-bomber built by McDonnell Douglas Corporation. ... Sidewinder Missile The AIM-9 Sidewinder is a heat-seeking, short-range, air-to-air missile carried by fighter aircraft and recently, certain gunship helicopters. ... See also: 2003 invasion of Iraq and Gulf War (disambiguation) C Company, 1st Battalion, The Staffordshire Regiment, 1st UK Armoured Division The Persian Gulf War was a conflict between Iraq and a coalition force of 34 nations led by the United States. ... The Boeing (formerly McDonnell Douglas) F-15 Eagle is an American-built all-weather tactical fighter designed to gain and maintain air superiority in aerial combat. ... MiG 25 Foxbat The MiG-25 (NATO reporting name Foxbat) is a high-speed interceptor and reconnaissance aircraft produced by the Soviet Unions Mikoyan-Gurevich design bureau. ...

External links

• ACTIVE AND SEMIACTIVE RADAR MISSILE GUIDANCE