In recent years, precision guided weapons play more and more important role in modern war. One of the greatest strengths of a precision strike missile is a reduction in the number of aircraft sorties required to destroy a target. One of the key contributors to the missile accuracy, lethality, and adverse weather capability of precision strike missiles is the advancements in missile seekers.
Strategy Analytics forecasts the global Smart Weapons (SW) market will grow to over $41.8 billion in 2025, representing a CAGR of 3.7%. A renewed emphasis on advancing Smart Weapon capabilities to counter evolving threats such as A2/AD (anti-access Area Denial) envelopes, combined with on-going demand from asymmetric wars and continued force modernizations in emerging countries is driving spending across the full range of Smart Weapons.
Precision guided weapons may include a variety of imaging or non-imaging sensors to detect and track potential targets. Sensors used to guide projectiles to an intended target are commonly referred to as seekers. Seekers may operate in various portions of the electromagnetic spectrum, including the visible, infrared (IR), microwave, and millimeter wave (MMW) portions of the spectrum. Some projectiles may incorporate multiple sensors that operate in more than one portion of the spectrum. A seeker that incorporates multiple sensors that share a common aperture and/or common optical system is commonly called a multimode seeker.
While optical systems (visible and IR) require clear atmospheric conditions for reliable operation, MMW imaging is relatively immune to weather conditions such as cloud, fog, snow, and light rain. The seeker can operate in low visibility and contaminated battlefield conditions, and is not susceptible to battlefield obscurants such as smoke, dust, flares and chaff.
Kongsberg to upgrade joint strike missiles with RF-seeker sensors
Kongsberg Defence Systems has received a contract from the Australian Department of Defence to install its RF-seeker sensors on joint strike missiles (JSM) that will be carried on-board F-35 fighter aircraft. Built by BAE Systems Australia, the RF-seeker sensor will allow the long-range precision strike missile to locate targets by their electronic signatures.
The potential upgrade will further strengthen the capabilities of JSM for the most challenging scenarios in a modern battlefield, Kongsberg stated. The JSM, which will be integrated for internal carriage on the F-35, is difficult to detect and stop even for the most advanced countermeasures and defence systems, Kongsberg stated. The missile uses a combination of advanced materials and can fly low, while following the terrain.
It is said to be the only long-range sea and land-target missile that can be carried internally in the F-35 and will allow the aircraft to fight well-defended targets across long distances.
USAF offers $100m funding for high-performance millimetre wave seekers
The US Air Force (USAF) has granted $100m in additional funding for the development of high-performance, millimetre wave seeker technology for munitions. As part of the Air Force small business innovation research (SBIR) Phase II contract, Texas-based L-3 Mustang Technology will combine an automatic target acquisition and tracking algorithm, intelligent target clustering and the capability to support a deployment demonstration.
Air Force Research Laboratory researcher Thomas Lewis said: “MMW seekers are active radar seekers with the capability to both transmit and receive information. “Because they provide their own illumination, they can be used day or night. Additionally, because of the wavelength they use, they allow us to see through both clouds and rain.”
Researchers are expected to transition the technology to the AFRL Munitions Directorate’s advanced development GBU-X (Flexible Weapons) programme.
AFRL GBU-X (Flexible Weapons) programme
The GBU-X program is a cross-directorate AFRL initiative that seeks to mature key technologies that could enhance current weapons or lead to a new family of weapons made up of flexible, interchangeable, open system architecture components for sixth-generation aircraft.
It explores two primary areas of technology research, including the development of open systems architecture with common interfaces to facilitate rapid technology refresh and configuration of the munition system to meet individual mission needs, and cooperative engagement strategies using networked and selectable effects munitions for increased robustness to countermeasures and improved endgame performance over baseline inventory munitions.
The program is also examining supportability and affordability of a family of GBU-X weapons.
Having an open architecture shall allow plug and play of sensors, reduce the need to develop and maintain vast number of disparate of weapon systems, resulting in lower USAF costs overall as well as reduce the time between when a weapon is developed and when it can be integrated onto a platform.
“Developing a common architecture that enables modular subsystems to achieve flexible weapons capability, while allowing us to refresh the technologies at the pace of better, more affordable and sustainable technologies as they are discovered and developed, is at the core of our mission,” said David Hayden, an AFRL researcher working on the project.
MMW wave seeker
The millimetric band seeker provides a high-resolution radar return image of the target, while the frequency gives a small beamwidth and therefore very high angular resolution and reduces unwanted clutter for the given antenna size, which is limited by the diameter of the missile.
The millimetre wave radar enables wideband operation, facilitating the use of very sophisticated electronic countermeasures. Millimetric radar attenuates more rapidly than conventional centemetric radar in rain, sleet and fog, but its advantage is high penetration, in comparison to infrared sensor systems when countermeasures are employed.
Automatic Target Recognition Technology
Automatic Target Recognition (ATR) technology for missile seekers homing on mobile targets is based on MMW image matching technology. An end-to-end ATR system used in operational environment requires four stages: image enhancement, target detection, target segmentation and target recognition. Images are preprocessed in the first stage for the best performance in the next three stages.
In the target detection stage non-target clutter in MMW images is rejected and potential targets are separated using Constant False Alarm Rate (CFAR) technologies that detect the targets while keeping the false alarm rate under a user defined threshold.
In the segmentation stage of ATR the output of CFAR detector is clustered to separate targets. Next, the detected target locations are clustered and segmented to obtain separate suspected targets. Clustering of the targets is achieved using morphological filters.
Target recognition is performed in the last stage of ATR processing. The role of target recognition is to accurately identify target of interest even in the presence of variability in target signatures. Only by accurate recognition of targets critical military operations, such as homing of fire-and-forget missile, can be achieved.
According to Hayden, the Air Force is interested in a mature automatic target acquisition approach that allows the Guided Smart Seeker to enter into closed-loop tracking without a human operator in the loop.
“One of the requirements we sought to meet was that the seeker possessed the ability to acquire targets and begin tracking them without human intervention,” Hayden said. “Intelligent target clustering is a capability that would give the seeker a more robust target tracking capability and reject any false alarms.”
Multi-Function RF Seeker Based on 3D Phased Array
Current RF seekers in use today have mechanical steerable antennas. In order to reduce the cost of the mechanical system and to significantly improve the performance of the missile seeker, the electrically controlled 3D antenna array is used. It results in a much more robust antenna which will be capable of steering much faster and more accurately than existing solutions. Furthermore, the antenna will provide an increased coverage and dwell time as a result of flexible beam steering. Additional degrees of freedom will allow it to carry out multiple tasks. Electronically steering of the radiation beam has many advantages over the traditional gimbaled system including faster beam steering time and increased space savings.