Metamaterials are a hot subject in microwave technology these days. Much of the work I see is going on with the design of antenna structures or substrate materials, but the researchers at Duke University have designed and tested a microwave cloaking device that can almost completely "hide" a small structure from microwaves. While this is not new news, they have more recent work going on to apply this technology to sound waves.
The Duke cloaking device is a structure made up of copper rings and wires patterned on a fiberglass composite. The structure is designed to route the microwaves around the hidden object inside and greatly reduces it reflection and shadow. The Duke team developed a small cloak (less than five inches across) that would provide invisibility in two dimensions, rather than three to simplify the design and prove out the concept. The cloak includes strips of metamaterial fashioned into concentric two-dimensional rings, a design that allows its use with a narrow beam of microwave radiation. The precise variations in the shape of copper elements patterned onto their surfaces determine their electromagnetic properties. The cloak design is unique among metamaterials in its circular geometry and internal structural variation, the researchers said. Up until that time all other metamaterials had been based on a cubic, or gridlike, design, and most of them have electromagnetic properties that are uniform throughout.
The researchers set out to prove the concept by aiming a microwave beam at a cloak positioned between two metal plates inside a test chamber, and used a detecting apparatus to measure the electromagnetic fields that developed both inside and outside the cloak. They first show a beam of microwaves hitting a 2 inch metal cylinder and then hide the cylinder within the cloaking structure. By examining an animated representation of the data, they found that the wave fronts of the beam separate and flow around the center of the cloak. Here is a video that demonstrates it:
So the Rumulans may have arrived on Earth but we may not be able to see them. What other interesting work have you seen using metamaterials???