Raytheon displayed the new radar it developed for the LTAMDS at the AUSA 2019 exhibition in Washington DC. Photo: Raytheon
LTAMDS uses three AESA arrays to provide complete 360-degree coverage. This image shows the two rear panels sized almost as the main array pointed forward.

The Raytheon Company announced it has been selected to provide the US Army with its next-generation, 360-degree capable radar – known as the Lower Tier Air and Missile Defense Sensor (LTAMDS).

Raytheon’s solution is designed to be fully operable with the U.S. Army’s existing architecture. As such, it will operate on the Army’s Integrated Air and Missile Defense network Battle Command System (IBCS). According to Raytheon’s officials, when the first LTAMDS radar rolls off the assembly line, the Army will be able to turn it on and it’ll connect automatically.

As a 360-degree sensor LTAMDS expands battlespace coverage to detect and engage air and missile threats coming from various directions, not only the forward arc traditionally covered by Patriot systems, including at very low altitude. Based on Raytheon’s radar design experience, the new system represents a ‘clean sheet’ approach, that enables the new sensor to automatically connect to the network upon deployment, without the need for network or system retrofit or upgrades.

The selection comes after the completion of a ‘Sense-Off’ competition held by the Army, in an effort to accelerate the development and fielding of the Patriot replacement radar and complete a modernization program as early as 2022. Under the current program, Raytheon will develop and supply six radar systems. Fielding plans call for the delivery of additional sensors to equip 15 Patriot battalions through 2031, though the Army maintains the option to evaluate and buy other sensors by that time. During the ‘Sense-Off,’ the Army also evaluated operational radar systems from Northrop Grumman and Lockheed Martin/IAI-Elta.

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[wlm_ismember]The Patriot radar is required to provide very low to very high-altitude surveillance, target detection, classification, identification and tracking, missile tracking and missile guidance while performing Electronic Counter-Countermeasures (ECCM) functions, all functions are done simultaneously. The key to this agility is the use of phased array technology, deploying static electronic arrays instead of rotating antennae.

The Patriot system’s original phased array radar was AN/MPQ-53, deployed by Raytheon for PAC-2 (Patriot Advanced Capability-2) system. When it was first deployed in 1985, PAC-2 improved the systems’ capability against SCUD type tactical ballistic missiles, a capability gap realized in the first Gulf War of 1991. AN/MPQ-65 radar was fielded in 2003 to supports the PAC-3 systems that further enhanced the Patriot capability against cruise missiles. Both radars use electronic phased array technology to detect targets at a range of 100 kilometers and can track over 100 targets, engaging nine of them simultaneously.

During the cold war, air defenses were designed to establish a dense ‘defensive wall’ covering airspace deep beyond the front line, since it was understood enemy air and missile attacks could come only from known directions. The development of stealth aircraft, cruise missiles, and loitering weapons have challenged those concepts, rendering sectorial sensors, particularly air defense and fire control radars vulnerable to attack. [/wlm_ismember]

The vulnerability of sectorial air defense systems was clearly demonstrated by the failure of Saudi Air Defenses to detect and warn of an air attack by Iranian cruise missiles and loitering weapons, that targeted oil refineries in Abqaiq and Khurais in Saudi-Arabia on the night of September 14, 2019. those weapons have flown bypassed the Saudi defenses by coming from the northwest, whereas the air defenses were pointed eastward, toward Iran. Deployment of sensors like LTAMDS is expected to close this gap, replacing the two sectorial covering types with full 360-degree coverage and higher sensitivity that improve the detection of small, agile and low signature targets.

[wlm_ismember] As a modular system, it will support all MIM-104 Patriot air and system variants. “With the U.S. Army’s approval, these Patriot partners will have the opportunity to add Active Electronic Scanned Array, 360-degree capability to their inventory, extending the life of their systems for many decades.” Said Ralph Acaba, President of Raytheon Integrated Defense Systems.

The Army wants a new 360-degree covering radar to replace the current radars that only cover a 120-degree sector. Under the contract, Raytheon will receive $384 million to deliver six production representative LTAMDS radar units under Urgent Materiel Release Rapid fielding by the end of 2022. Production assets are scheduled for delivery starting FY24.

Raytheon’s LTAMDS is a 360-degree, Active Electronically Scanned Array radar powered by Gallium Nitride (GaN) transmit/receive (T/R) modules, providing a significant increase in transmission power and signal to noise ratio, thus delivering higher sensitivity and better resilience against interference and electronic attack. Over the past two decades, Raytheon has invested significantly in AESA GaN technology and advanced manufacturing capability that has already been implemented in modular assemblies that are scalable and configurable in a number of radar systems.[/wlm_ismember]