The Evolution of Radar Technology: From MAR to AESA

The history of radar technology is marked by significant advancements that have played a crucial role in military defense systems. One of the pivotal moments in this history was the proposal by Bell Labs in 1960 to replace the Nike Zeus radars with a phased array system. This led to the development of the Zeus Multi-function Array Radar (ZMAR), an early example of an active electronically steered array radar system. The ZMAR was a groundbreaking system that could perform multiple functions simultaneously, a feat not possible with the mechanically steered radars of the time.

The ZMAR evolved into the Multi-function Array Radar (MAR) when the Zeus program shifted focus to the Nike-X system in 1963. The MAR was composed of numerous small antennas, each linked to a computer-controlled transmitter or receiver. This configuration allowed for advanced beamforming and signal processing, enabling the MAR to detect long-range targets, differentiate between warheads and decoys, and track outbound interceptor missiles.

The MAR’s capabilities meant that a single site could manage the entire battle over a vast area. Each MAR, along with its associated battle center, could process information for hundreds of targets, selecting the most suitable battery to engage each one. While one battery was typically associated with the MAR, additional batteries were positioned around it, equipped with simpler Missile Site Radars (MSR) to track the Sprint missiles.

Despite its success, the MAR system was incredibly costly, and as the complexity of anti-ballistic missile (ABM) scenarios grew, the Nike-X concept was eventually abandoned in favor of simpler systems like the Sentinel program, which did not utilize MAR technology.

Internationally, radar technology was also advancing. The Soviet Union developed the first Soviet APAR, the 5N65, as part of the S-225 ABM system between 1963–1965. Although modifications were made, and the radar was built at the Sary Shagan Test Range in 1970–1971, the S-225 system was never commissioned.

In Japan, the first military ground-based Active Electronically Scanned Array (AESA) radar, the J/FPS-3, became operational in 1995 with the 45th Aircraft Control and Warning Group of the Japan Self-Defense Forces. The AESA technology marked a significant leap forward, offering greater agility, reliability, and performance.

The AESA technology was quickly adopted in various platforms:

• The OPS-24, a fire-control radar on the Japanese Asagiri-class destroyer DD-155 Hamagiri launched in 1988, was the first series production ship-based AESA.
• The EL/M-2075 Phalcon, mounted on a Boeing 707 of the Chilean Air Force in 1994, was the first airborne series production AESA.
• The J/APG-1, introduced on the Mitsubishi F-2 in 1995, was the first AESA on a combat aircraft.
• The seeker head for the AAM-4B air-to-air missile, used by the Mitsubishi F-2 and Mitsubishi-built McDonnell-Douglas F-15J, became the first AESA on a missile.

In the United States, Northrop Grumman and Raytheon emerged as leading manufacturers of AESA radars, supplying technology for the F-22 and Super Hornet. These companies also produced the transmit/receive modules that form the core of AESA radars, with technology developed through Department of Defense research programs like the MMIC Program.

The evolution of radar technology reflects the continuous pursuit of enhanced defense capabilities. As threats have become more sophisticated, so too have the systems designed to detect and neutralize them. The shift from mechanically steered radars to AESA represents a significant milestone in this journey, providing the agility and precision required for modern warfare. The ongoing development of radar technology remains a critical element in ensuring national security and defense readiness.