Radar technology has played an integral role on the battlefield since the Second World War and has been a game changing technology for situational awareness ever since.
Radar was developed significantly throughout the 1950s and 60s when the Doppler principle was widely integrated into systems. The Doppler effect occurs where a radar emits pulses of energy that then hit an object and travel back to the radar receiver. By analyzing the variation in how the object’s motion has altered the frequency of the returned signal, highly accurate measurements of the target’s velocity relative to the radar can be made.
The Doppler effect became the foundation for Synthetic Aperture Radar and Inverse Synthetic Aperture Radar, which gives a two-dimensional high-resolution image of a target. The first electronically steered phased array radars emerged in the 1960s and these were used to detect ballistic missiles and satellites. Advancement in radar using digital technology in the 1970s paved the way for modern radar systems and saw radar being deployed onto spacecraft for remote sensing.
Today, radar forms the bedrock of modern military operations. It enables enhanced situational awareness and surveillance in any weather, at any time of day and in any atmospheric conditions. It is critical in terms of the ability to track stealthy assets that are widely used across theaters all over the world.
Complexity of the battlefield
The battlefield has changed dramatically since radar was first used during WW2 and therefore radar technology has had to evolve with it. Huge advancements in airborne technology have seen the introduction across the years of helicopters, stealth aircraft and Unmanned Aerial Systems (UAS) that offer increased ISR (intelligence, surveillance, reconnaissance) capabilities. These are combined with precision weapons and attacks today are multi-pronged, meeting the enemy from both air and ground. Huge leaps forward in communications technology enable operators to lift the fog of war and to give a detailed picture of exactly what is going on and where on the battlefield through imagery, video, sensors and communications, helping to aid fast decision-making. Combat has become more technology-based, and more remote with less of an emphasis on boots on the ground and more emphasis on technological capability using detection, tracking, jamming and other capabilities to overcome adversaries.
How Stealth Works
Low Observable (LO) technology, otherwise known as stealth technology, is a set of technologies that reduce the distances at which an object can be detected by reducing its Radar Cross-Section (RCS), thus minimizing vehicle, vessel or aircraft detection. This can be achieved in a number of ways. The design of an aircraft, for example may employ shaping features that send the echo radar signal elsewhere, other than back to the radar. Different coatings or materials can be used on the body of the aircraft that either absorb or scatter the radar signal so that they cannot reflect back onto the radar. Another cancellation layer can be used on top of this to scatter the signal for a second time, again preventing it from reaching the radar. Active transmitters located on the aircraft can also be used to cancel incoming signals.
Stealth technologies such as the ones above enable an aircraft or a vessel to be more agile, flexible and mobile and, above all survivable. It also enables the user to get deeper into enemy zones to mount surprise attacks at a much lower risk of being detected.
Counter Low Observable Radar (CLO)
This type of stealth capability has obviously created challenges for radar systems and radar development has evolved to encompass various technologies that enable tracking and detection of stealth targets.
Low frequency radar (30-300MHz) and UHF (300 MHz – 1 GHz) use much longer wavelengths than fighter aircraft and in this range geometric stealth, which is the design used in stealth aircraft to deflect waves, is not as effective.
The offsetting of the receiver is another technique employed to overcome stealth. In a monostatic radar system, the transmitter and receiver are located in the same place and this is what stealth aircraft are designed to deflect. However, using a bi- or multi-static system, the transmit and receive components are separated, so that the returned waves can be detected instead of deflected.
Doppler radar can also be used to overcome stealth. As we discussed earlier in the article, the frequency variation caused by the Doppler effect can filter out stationary targets and isolate moving targets. However, the success of the Doppler effect depends on the angle of approach, such as a target traveling directly towards the radar. When this happens, signal processing can be used to take other sets of information such as speed and altitude to determine the track of the object.
Emerging radar technology
Emerging radar technology is taking the field to another level of capability. Let’s take a look at some of the disruptive advancements that are fast gaining ground.
Quantum radar
Quantum radar is an emerging field that promises to rewrite radar capabilities and to potentially override stealth technology that we have seen militaries rely on for decades.
Quantum radar utilizes quantum mechanics to detect objects by using Quantum Entanglement. The radar sends out quantum entangled signals that are linked to a reference signal which remains at the radar receiver. This link to the reference signal enables the system to distinguish this signal even if it is extremely faint when the signal is returned. It effectively allows the radar to acknowledge that signal even in an environment where there is a lot of background ‘noise’, enabling much better target detection than traditional radar systems. This is highly suited to military and defense applications and could potentially disrupt the field of stealth technology as it is picking up tiny signals that cannot be detected by classic radar systems.
Use of AI
The integration of AI into radar systems is set to transform the radar sector, ushering in a new era of capability that promises to be invaluable as the defense sector looks to become more effective and efficient in its operations.
AI can assist in a plethora of ways. In terms of signal processing, traditional systems rely upon predefined algorithms whereas AI means adaptive techniques can be used to detect targets amid noise and can even be used to suppress clutter so that relevant signals are amplified. AI can also adapt the sensitivity of the system in line with different environmental conditions and enable the differentiation between objects using neural networks. In terms of threat detection, AI can learn how to recognize certain threats, to track multiple targets and therefore improve the reliability of the system to detect those threats.
Radar systems can also be made more reliable using predictive maintenance where anomalies can be identified before they happen and repairs can be carried out before any failure occurs.
Cognitive radar is now also opening the door to systems that can make autonomous decisions and can modify behavior of the system to adapt to different situations. The AI market for radar is set for huge growth as the demand for autonomous operations and smarter and faster radar capabilities increase.
Antenna developments
The use of phased array technology is increasing as it develops and becomes more affordable. With no moving parts and the ability to scan, steer and focus it is a highly reliable and rapid technology that requires minimum maintenance. Phased array technology is also very compact which is suitable for platforms that are moving such as aircraft and vehicles, making it attractive to defense users. Use of emerging techniques such as phase-only beamforming are resulting in higher power efficiency and simpler design.
Keep pushing the boundaries
In this article, we have only just scratched the surface of radar and what’s possible. There is so much development to come. Radar remains fundamental to defense networks all over the world and it is imperative that the sector continues to innovate and go beyond. By focusing on development and innovation and making new discoveries in the technology, we can strengthen security and help to make the world a safer place.