Study Finds Cloaking Possible with Ordinary Plastic_Featured_, Technology Monday, October 8th, 2012
(Phys.org) A metal object can be made invisible with the help of ordinary plastic, Pekka Alitalo and Constantinos Valagiannopoulos, researchers from the School of Electrical Engineering, have shown in their study.
The object, however, does not become invisible to the human eye – only to electromagnetic radiation at microwave frequencies. In practical terms, this means that electromagnetic waves travelling, for example, between two antennas, do not detect an object located in their path, allowing the waves to travel the distance between them despite the obstacle, without any disruption to communications.
Previously, a similar effect has only been achieved using complex devices or expensive metamaterials with a right electromagnetic response. In contrast, the method developed by Pekka Alitalo and Constantinos Valagiannopoulos is simple and affordable.
Plastic decreases electromagnetic scattering
Pekka Alitalo explains that objects are visible because they scatter light which is electromagnetic radiation. A metal object will not, however, scatter electromagnetic radiation at microwave frequencies to the same extent when covered with a dielectric material – an insulator that does not conduct electricity. One such dielectric material is ordinary plastic used by Alitalo and Valagiannopoulos.
“Because of space limitations, often something has to be placed in front of an antenna, such as a support structure or another antenna, and the radiation transmitted by the antenna cannot then travel through the object. We were especially interested in cloaking metal objects as metal is a material that causes strong scattering and as such, greatly interferes with communications”, Alitalo explains.