What are the advantages and disadvantages of passive and active radar stealth?

1 Passive radar stealth

Passive radar stealth involves shaping, coating, or absorbing the radar waves that hit the object, so that less of them are reflected back to the source. This reduces the radar cross section (RCS), which is a measure of how visible an object is to radar. For example, stealth aircraft have angled surfaces, smooth edges, and special materials that minimize their RCS. Passive radar stealth is effective against most conventional radar systems, but it also has some drawbacks. It can limit the design, performance, and payload of the object. It can also be compromised by other sources of electromagnetic radiation, such as infrared, optical, or acoustic sensors.

2 Active radar stealth

Active radar stealth involves emitting signals that interfere with or cancel out the radar waves that hit the object, creating a false or reduced image. This can be done by jamming, spoofing, or masking the radar system. For example, some stealth aircraft have electronic warfare systems that can jam or confuse the enemy radar. Active radar stealth can enhance the passive stealth by creating gaps or decoys in the radar coverage. However, it also has some challenges. It can be detected by other sensors that can locate the source of the emission. It can also be countered by advanced radar systems that can filter out or adapt to the interference.

3 Radar detection and evasion

Radar detection and evasion are complex and dynamic processes that depend on many factors, such as the frequency, power, and polarization of the radar waves, the distance and angle of the object, the background noise and clutter, and the countermeasures and counter-countermeasures of both sides. Therefore, there is no single or perfect solution for radar stealth. Rather, it is a trade-off between different options and scenarios. For example, some objects may use a combination of passive and active radar stealth, or switch between them depending on the situation.

4 Radar signatures and profiles

Radar signatures and profiles are the characteristics of an object that determine how it appears on a radar screen. They include the RCS, the Doppler shift, the radar return time, and the modulation of the signal. By analyzing these features, a radar system can identify, classify, and track an object. However, by manipulating these features, an object can also deceive or evade a radar system. For example, some objects may use stealth coatings, chaff, flares, or maneuvering to alter their radar signatures and profiles.

5 Radar invisibility and cloaking

Radar invisibility and cloaking are the ultimate goals of radar stealth, but they are also the most challenging and elusive ones. They involve making an object completely undetectable or indistinguishable from the background by any radar system. This would require either absorbing or bending all the radar waves around the object, or creating a perfect replica of the background on the object. Some theoretical and experimental methods have been proposed for radar invisibility and cloaking, such as metamaterials, plasmonics, or quantum optics, but they are still far from practical applications.

6 Radar stealth and warfare

Radar stealth and warfare have a long and intertwined history, dating back to the development of radar and its use in World War II. Since then, radar stealth has been a key factor in many military operations and conflicts, such as the Cold War, the Vietnam War, the Gulf War, and the War on Terror. Radar stealth has given some advantages to the users, such as surprise, stealth, and survivability, but it has also provoked some responses from the adversaries, such as innovation, adaptation, and deterrence. Radar stealth and warfare are likely to continue to evolve and influence each other in the future.