Patriot Air-Defence System, United States of America

Patriot is a long-range, all-altitude, all-weather air defence system to counter tactical ballistic missiles, cruise missiles and advanced aircraft. Patriot (MIM-104) is produced by Raytheon in Massachusetts and Lockheed Martin Missiles and Fire Control in Florida.
As well as the US, Patriot is in service in Egypt, Germany, Greece, Israel, Japan, Kuwait, the Netherlands, Saudi Arabia and Taiwan.
Patriot missile systems were deployed by US forces during Operation Iraqi Freedom. The systems were stationed in Kuwait and successfully destroyed a number of hostile surface-to-surface missiles, using the new PAC-3 and guidance enhanced missiles.

Guidance enhanced missile (GEM-T) upgrade.

The Patriot missile is equipped with a track-via-missile (TVM) guidance system. Midcourse correction commands are transmitted to the guidance system from the mobile engagement control centre.

The target acquisition system in the missile acquires the target in the terminal phase of flight and transmits the data using the TVM downlink via the ground radar to the engagement control station for final course correction calculations. The course correction commands are transmitted to the missile via the missile track command uplink. The high-explosive 90kg warhead is situated behind the terminal guidance section.
The range of the missile is 70km and maximum altitude is greater than 24km. The minimum flight time is the time to arm the missile, which is less than nine seconds, and the maximum flight time is less than three and a half minutes.
Raytheon has developed the Patriot guidance enhanced missile (GEM-T), an upgrade to the PAC-2 missile. The upgrade involves a new fuse and the insertion of a new low noise oscillator, which increases the seeker's sensitivity to low radar cross-section targets.
The GEM-T missile provides an upgraded capability to defeat air-breathing, cruise and ballistic missiles, as a complement to the PAC-3 missile. The first upgrade forebodies were delivered to the US Army in November 2002.
By September 2010, a total of 1,000 Patriot missiles were upgraded for the US Army.
In July 2008, South Korea placed an order for 64 GEM-T upgrade kits. In April 2011, US Army Aviation and Missile Command awarded a $58.3m contract to upgrade 131 PAC-2 missiles to GEM-T missile configuration.
In July 2008, South Korea placed an order for 64 GEM-T upgrade kits.

Patriot advanced capability (PAC-3) missile.

A new Patriot advanced capability (PAC-3) missile has increased effectiveness against tactical ballistic and cruise missiles, through the use of advanced hit-to-kill technology. Lockheed Martin is the prime contractor, with Raytheon the systems integrator. The PAC-3 has a Ka-band millimetre wave seeker developed by Boeing.
The missile guidance system enables target destruction through the kinetic energy released by hitting the target head-on. 16 PAC-3 missiles can be loaded on a launcher, compared to four PAC-2 missiles.
PAC-3 entered low rate initial production in late 1999 and first LRIP production missiles of a total of 92 were delivered in September 2001. A contract for 88 missiles was placed in December 2002 and another for 12 in March 2003.
The missile was first deployed during Operation Iraqi Freedom in March / April 2003. In February 2004, Lockheed Martin was awarded a production contract for 159 PAC-3 missiles, which includes 22 missiles to replace those expended in Iraq. Deliveries were concluded by April 2006.
A further contract for 156 missiles was received in February 2005. Of these missiles, 32 are for the Netherlands and 16 for Japan, under foreign military sales (FMS) agreements. The Netherlands received the first PAC-3 missiles in October 2007. The US Army ordered another 112 missiles in May 2006 and 112 in March 2007.

PAC-3 missile segment enhancement (MSE)

The PAC-3 missile segment enhancement (MSE) is part of a spiral development being undertaken by Lockheed Martin.
The increased range MSE gives the missile a more powerful rocket motor for added thrust and larger fins for increased manoeuvrability against faster and more sophisticated ballistic and cruise missiles. The MSE began flight testing in May 2008.
The PAC-3 MSE is the baseline interceptor for the multinational medium extended air defence system (MEADS) under a contract placed in February 2008. The missile was successfully test fired using the Patriot system in May 2011. Lockheed Martin was awarded a $68.9m contract in July 2012 to prepare the PAC-3 production line for the PAC-3 MSE missile.
The PAC-3 MSE successfully destructed a tactical ballistic missile (TBM) target at White Sands Missile Range in December 2012.

M901 launching station

The M901 launching station transports, points and launches the Patriot missile. Each launcher has four missiles. The launcher is remotely operated via a VHF or fibre-optic data link from the engagement control station, which provides both the missile prelaunch data and the fire command signal.

Engagement control station

The AN/MSQ-104 engagement control station is the only manned station in a Patriot fire unit. The control station communicates with the M901 launching stations, with other Patriot batteries and the higher command headquarters.
The control station is manned by three operators, who have two consoles and a communications station with three radio relay terminals. The digital weapon control computer is located next to the VHF data link terminals.

 Radar on the air defence system

The AN/MPQ-53 phased array radar carries out search, target detection, track and identification, missile tracking and guidance and electronic counter-countermeasure (ECCM) functions. The radar is mounted on a trailer and is automatically controlled by the digital weapons control computer in the engagement control station, via a cable link. The radar system has a range of up to 100km, capacity to track up to 100 targets and can provide missile guidance data for up to nine missiles.
The US Army Patriot radars are being upgraded by Raytheon. The upgrade kits provide greater power for the radar and the addition of a wideband capability for improved target discrimination.
A target engagement can be carried out in manual, semi-automatic or automatic mode. When the decision has been made to engage the target, the engagement control station selects the launch station or stations and pre-launch data is transmitted to the selected missile. After launch, the Patriot missile is acquired by the radar.
The command uplink and the TVM downlink allow the missile's flight to be monitored and provide missile guidance commands from the weapon control computer. As the missile approaches the target, the TVM guidance system is activated and the missile is steered towards the target. A proximity fuse detonates the high-explosive warhead.