How Aerospace Composites Can Reduce Aircraft Radar Signatures
Certain types of aircraft, particularly those used by the military, are designed specifically with reduced aircraft radar signatures in mind. Reducing an aircraft’s radar signature can be done in a number of ways. Typically, engineers combine modern design principles with aerospace composites to get the job done.
Common composite materials include fiberglass and carbon fiber. More advanced applications may call for the use of ceramic matrix composites. Regardless of the particular materials chosen, composites offer some unique properties that make them ideal for reducing radar signatures.
Electromagnetic Properties
Radar systems rely on electromagnetic waves to detect and track objects as they move through the air. A radar transmitter sends out radio or microwaves while a receiver measures the waves as they are reflected off the target and back to the system. With that being the case, one of the ways to reduce an aircraft’s radar signature is to disrupt the electromagnetic wave movement.
Aerospace designers do this in two ways:
- Absorption – Electromagnetic waves cannot reveal the position of an aircraft if they never make it back to the radar system. Fortunately, aerospace composites can be engineered with superior absorption capabilities.
- Deflection – Not all electromagnetic waves can be absorbed on contact. But composites can also be engineered to deflect those waves that are not absorbed. Waves are deflected away from the radar system and become virtually unusable for identifying and tracking aircraft.
Engineers also have the ability to tailor aerospace composites to very specific electromagnetic property requirements. The more precise their electromagnetic control, the more effective they are at eliminating radar signatures.
Utilizing the Layered Approach
Composites are better at absorbing electromagnetic waves when they are built with a layered structure. For instance, a structure consisting of multiple layers of alternating dielectric or conductive materials is extremely radar-absorbent.
Mastering the layering technique maximizes absorption across a range of frequencies, giving engineers the upper hand against even the most modern radar systems. But layering alone does not guarantee 100% stealth. So engineers need to consider other things as well.
Speed and Maneuverability Matter
An aircraft’s speed and maneuverability play a role in how easily it is identified and tracked. The faster and more maneuverable an aircraft is, the harder it is for radar systems to watch it. How do you make aircraft faster and more maneuverable? You build with aerospace composites.
Whether it is fiberglass, carbon fiber, or ceramic matrix composites, all aerospace composites offer an impressive strength-to-weight ratio. Composites are magnitudes lighter than steel and aluminum. At the same time, they are much stronger.
Reducing weight increases speed and maneuverability. In a passenger or cargo transport scenario, there is less concern about radar tracking. But in a military scenario, radar is bad news. Faster, lighter, and more maneuverable aircraft are preferred for military applications because they are not so easy to track.
Composites and Impedance Matching
Impedance matching is a crucial component in radar tracking. From the radar operator’s perspective, mismatches lead to power loss and less accuracy due to reflection. From the pilot’s perspective, however, it is a different matter.
Pilots want accurate impedance matching because it simultaneously reduces reflection losses and increases wave absorption. The more electromagnetic waves absorbed by the aircraft, the less likely that aircraft is to show up on radar. Composites play a role by improving impedance matching.
Radar is one of the best defensive tools against enemy aircraft. Aerospace engineers know this. Their job is to defeat radar by making planes invisible. Eliminate the radar signature and that is exactly what you will do. Composite materials make it very possible thanks to their unique properties.