Hidden Content
New construction materials made of composites could make military vehicles—and even soldiers—invisible to radar, sonar, and even the naked eye.

Metamaterials are composite materials designed to manipulate light, radar, and sonar waves.
Objects made of metamaterials could render themselves invisible to most types of sensors—including the human eye.
Metamaterials are difficult to make and still a ways from mass production.
The development of new so-called metamaterials could lead to dramatic advances in military technology, particularly the ability to hide from sensors—even the human eye. Metamaterials, engineered composites designed to manipulate the electromagnetic spectrum, could lead to “invisible” tanks and armored vehicles, submarines undetectable by sonar, and weapons with improved seekers and guidance systems.
The big caveat though is that metamaterials are currently pretty difficult to manufacture and are still years away from full-scale production.

A new article in the October issue of the U.S. Naval Institute Proceedings outlines potential military applications for metamaterials. Metamaterials of plastic and metal and engineered in lattice-like patterns up to a billionths of a meter in scale. The result is a surface or material that can manipulate an object’s magnetic or electrical field in ways traditional building materials cannot. This allows them to alter how energy waves across the electromagnetic spectrum (visual light, radar, radio, acoustic waves, etc.) interact with them with some pretty stunning implications.

The working principle behind metamaterials is known as Snell’s Law, which the article describes as follows:
When an energy wave travels through a medium (e.g., space, air, water, glass), crosses a boundary, and interacts with another medium, the wave refracts (bends). Think of light bending as it passes through a prism. This phenomenon is known as Snell’s Law. When this wave encounters an object, parts of the wave are either reflected, dispersed, or absorbed. When this wave encounters an object, parts of the wave are either reflected, dispersed, or absorbed.
Almost all sensors measure reflection or absorption of reflected energy. The human eye, for example, measures reflection of sunlight from objects, and radar observes reflection off radar waves from objects. The same objects made of metamaterials could achieve near-zero reflection and absorption. The implications are huge: a tank, aircraft, submarine, or even soldier’s uniform made of metamaterials could appear invisible to radar waves, sonar waves, and even light.

That’s the more fanciful application. Other military applications include creating surfaces that double as communications antennas: a fighter jet's wing could become one large antenna. At sea, warships could replace large antennas and arrays with a single stealthy mast made out of metamaterial. Metamaterials could also allow sensors on missiles to pick up objects at even greater ranges, enhancing their usefulness on the battlefield.
Metamaterials have been around for 20 years but progress developing them has been slow. Manufacturing, involving different types of materials creating lattice patterns at extremely small scales, is difficult. There's no theoretical reason why that won't be overcome in the future, and when they do metamaterials could indeed reshape warfare.