Stealth technologies refer to a wide range of techniques used to make aircraft, ships, submarines, missiles, satellites and ground vehicles less visible (ideally invisible) to radar, infrared or other detection systems. It is used to avoid detection, but may also be used to combat detection.
After World War II ended, the United States Military started a stealth program. It was designed to provide an effective method of saving aircraft from enemy airborne bombings and radar spotting.
Although stealth technologies can only be classified, some basic information is available about them.
Low observability
Stealth designs use a variety surface materials and coatings to reflect radio waves. This delays their reflection onto an enemy's radar. Some designs feature smooth, rounded shapes. Hidden engines and other devices can be used to reduce reflectivity.
Radar can see aircraft
It is essential to ensure that aircraft stealth can be achieved by keeping all parts as cool and comfortable as possible. This includes avoiding hot materials like engine exhaust gas and wing surfaces emitting infrared radiation. This radiation is used to target aircraft by heat-seeking missiles or other weapons. It should be kept as low as possible.
Planar shape
Planar design is the most important stealth technology in aircraft. It is a simple technique to disguise an aircraft to radar.
You can achieve this by designing the aircraft's body with a large surface area to volume ratio, and a small physical cross-section. This helps reduce radar reflections and increases the aerodynamic efficiency.
Another stealthy technology is radar absorption materials, or RAMs. These materials can be made of a variety of polymers including glass-fiber composites or multi-walled carbon nanotubes.
Radar absorbing materials can be applied directly onto the aircraft's exterior or embedded into a structure. The latter option is more common and offers many advantages over it.
RAM can absorb radar energy, but it does not generate it. This makes it a thin layer that covers most of the aircraft's surface. It is quite thin so it can be difficult to spot, but radar is able to see it.
An effective RAM material can absorb a large amount of RF energy, so it can greatly reduce the reflected signal from a target. This decreases the likelihood of a target being detected in a radar system with limited frequency or bandwidth coverage.
Plasma stealth
Plasma stealth has been introduced as a new stealth technology. This technology has the advantage of a very narrow beamwidth. It is not like traditional antennas. Instead, it uses a series of parallel tubes which are filled with gas. Then they are energized.
This antenna can send many signals but is only useful when the aircraft is flying at very low speeds. It is currently not possible to install large quantities of plasma stealth antennas on military planes.