From The Editor | February 29, 2024

Detecting, Tracking, And Discriminating Incoming Threats With X-Band Radar

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By John Oncea, Editor


X-Band radar is used extensively in military defense, automotive safety, and environmental monitoring where its versatility extends to applications such as missile guidance systems, aerial surveillance, and advanced driver-assistance systems. It’s also highly effective at sea, including in the Sea-Based X-Band Radar.

Since it was first developed in the 1930s, radar has changed dramatically. From the delivery of transmitters and receivers with greater precision to more efficient power use to significant size reduction, radar has improved in almost every way.

Today, according to BNN Breaking, radar – specifically X-Band radar (XBR) technology – “can distinguish between objects mere inches apart, thousands of miles away in space, or mere feet above the ground.” As a result, high-resolution XBR systems are now integral to national defense, automotive safety, and even environmental monitoring.

X-Band 101: The Basics

XBR operates in the frequency range of 8-12 GHz, allowing it to provide superior target resolution, accuracy, and the advantage of smaller antenna sizes. These features make XBRs highly sought after in both military and civilian applications, leading Allied Market Research to project the global radar industry to reach $44.35 billion by 2028.

“In recent years,” adds Qorvo, “electronic control elements for beamforming have become increasingly popular, providing more flexibility and increased benefits in the latest generations of X-Band solutions. The advancements in X-Band have given way to significant growth in the global radar industry.”

XBR has many uses, including remote sensing, navigation and ship traffic control, measuring waves and currents, and specific targeting operations. It is also capable of higher-resolution imaging and meteorological radar in which it can detect small water particles and light precipitation such as snow.

“The versatility of XBRs is perhaps most vividly illustrated in their range of applications,” writes BNN Breaking. “In the defense sector, they play a crucial role in missile guidance systems and aerial surveillance, offering unmatched precision in detecting and tracking targets. Similarly, in automotive safety, XBRs contribute to advanced driver-assistance systems (ADAS), enhancing vehicle detection and collision avoidance capabilities.”

The creation of small dual-polarization X-Band monopulse feed antennas has brought about new opportunities for satellite communication, especially for tracking Low Earth Orbit (LEO) satellites. This development highlights the potential of X-Band technology to change the landscape of not only terrestrial but also space-based communication and observation.

Inside An X-Band Radar

During Qorvo’s Design Summit webinar, X-Band Radar Application with Integration Guidance, Qorvo Senior Product Line Manager Fouad Boueri provided details on each functional component area of next-gen XBR, defining the main function of the component in the system as well as what tradeoffs need to be considered during the design. Summarizing Boueri’s talk, Qorvo writes:

  • Limiter – protects the LNA from damage by large incidents of power at the input.
  • Switch – routes the RF signal between the transmit and receive paths with optimal signal-to-noise ratio (SNR), power level, and isolation between T/R and provides robustness on the input from the antenna.
  • Phase shifter – controls the relative phase for each antenna element of the array system to electrically shape and steer the beam.
  • Digital step attenuator – attenuates the RF signal by controlling power and gain for beam steering and tapering.
  • Filter – provides signal conditioning such as isolation, coexistence, and mitigation of interference.
  • LNA – provides amplification of the received signal and provides system sensitivity.
  • Power amplifier – amplifies the transmit signal with high efficiency.

“Boueri's insights into the key components and considerations for optimal system performance underscore the complexity and precision involved in modern radar systems,” writes BNN Breaking. “From the integration of cutting-edge semiconductor materials to the meticulous calibration of antenna arrays, the evolution of XBR technology is both a technical and a creative endeavor.”

SBX-1: Radar At Sea

XBR is installed on most large research vessels and many offshore installations. This includes the Sea-Based X-Band Radar (SBX), part of the U.S. Ballistic Missile Defense System (BMDS) that is designed to detect and establish precise tracking information on ballistic missiles, discriminate missile warheads from decoys and debris, provide data for updating ground-based interceptors in flight, and assess the results of intercept attempts.

SBX is a floating, self-propelled, early-warning radar station that is a combination of the world’s largest phased-array XBR and is carried aboard a mobile, ocean-going semi-submersible oil platform. SBX’s capabilities include:

  • Detecting and tracking ballistic missiles
  • Differentiating missile warheads from decoys and debris
  • Providing data for updating ground-based interceptors in flight
  • Producing high-resolution images of incoming threat clouds
  • Helping BMD interceptors distinguish between debris and lethal objects

“SBX-1 was designed for exceptional stability in high winds and storms to withstand extended deployments in austere environments conducting Homeland Defense operations against ballistic missile attacks,” writes PIDC Construction, which led preconstruction and planning efforts, as well as overseeing the removal of legacy system equipment and installation of upgraded LCCS components within the vessel readiness window. “It measures 240 feet wide by 390 feet long, and houses a power plant, bridge and control rooms, living quarters, storage areas, and infrastructure to support the central XBR is the world’s largest X-band phased-array radar, measuring nine stories in height.”

The XBR system was created and is managed by Raytheon Technologies and is composed of over 45,000 modules mounted on an antenna face that can rotate up to +/- 270 degrees in azimuth and from 0 to 80+ degrees in elevation. To maintain optimal operating temperature, the Liquid Conditioning and Circulating System (LCCS) supports the XBR. When the radar is not in use, heat may need to be added to the system, and when it is in operation, the LCCS must quickly eliminate the extensive heat loads produced.

According to the Missile Defense Advocacy Alliance (MDAA), “The SBX platform that houses the radar carries a crew of about 85 and includes a bridge, control rooms, living quarters, storage areas, a power generation area, a helicopter landing pad, and maintains 60-days of supplies and fuel. It also houses a command, control, and communications system and an In-flight Interceptor Communication System Data Terminal that provides missile tracking and target discrimination data to interceptor missiles. The platform vessel is 389 ft long with a 238 ft beam, displaces 32,690 tons, and can move at up to 8 knots.”

SBX-1 was officially deployed in 2006 and, during the mid to late 2000s, traveled around the Pacific, spending time in port along the U.S. West Coast and the waters around Hawaii and Alaska. Though it was homeported in Adak, AK, it never actually visited the port or moored there. In 2009, the SBX was relocated to the waters around Hawaii due to North Korea’s nuclear attack threat on the island.

SBX-1 “is currently deployed in the Pacific Ocean to monitor for potential North Korean ICBM test launches,” MDAA writes. “The radar had previously been moored in Pearl Harbor on limited test support status since September of 2019. It has detected and tracked several targets or interceptors during GMD tests, including one in May 2017 while at sea.”

Pearl Harbor’s “Giant Golf-Ball-Shaped Radar”

Before being deployed in March 2023, SBX-1 was moored at Pearl Harbor, HI “for a few months for maintenance and about $70 million of upgrades,” Hawaii News Now reported. While there, MDA SBX product manager Bob Dees spoke about how SBX-1’s 2,400-ton radar can be rotated in a matter of seconds.

“We can look in any direction, we mechanically slow it,” Bob Dees. “We also can lift it to look straight up.” While other early warning radars can detect missiles, Dees said SBX-1 can see targets more clearly to determine if it’s an actual threat. “We look at the shape, look at the characteristics, and could look at a lot more details.”

Hawaii News Now adds, “Once a threat is identified, usually by satellite, radars in Japan, Alaska, and California work together with SBX-1 on precision tracking and data is sent to military operation stations on shore.”

“We have to see it in time that they can figure out that they want to shoot it, initialize the interceptor, and get it launched so that it can intercept before it gets to where it does some damage,” said Dees, who explained the advantage of a mobile, sea-based radar is its ability to track a missile’s trajectory from any part of the ocean and adjust to the curvature of the Earth.

“We’re the long-range part that can be reset if they want to beef up coverage for an area or increase the time that they have for command and control and engagement to get more shots off or more decision time.”

The Future Of X-Band Radar

Despite the benefits of XBR, there are concerns. “The transition to Active Electronically Scanned Array (AESA) radars, as discussed in Armada International, underscores the challenges of balancing cost, weight, and performance in radar design,” BNN Breaking writes. “AESA radars, with their enhanced reliability and multi-function capabilities, represent the future of radar technology. Nevertheless, integrating these systems, particularly in X-Band applications, requires overcoming significant engineering and financial obstacles.”

The future of XBR technology seems promising, as its trajectory points toward potential applications that could go beyond our current imagination. The possibilities for XBRs to contribute to societal advancement are immense, ranging from autonomous vehicle navigation to climate monitoring and more. However, the pace and breadth of these contributions will depend on the commitment to overcoming the inherent challenges of radar design and integration, as technology continues to evolve.