Scientists from the Toronto University have discovered a method to cloak an aluminum cylinder using a series of circular radio antennas to mask the object from radio waves. The experiment was conducted by Professor George Eleftheriades and his student Michael Selvanayagam currently pursuing his PhD at the university which involved using loops of antenna to reflect electromagnetic waves. Metamaterials, or artificial materials which possess properties that are not innately found in nature, are used to achieve the cloaking effect on objects by dispersing electromagnetic waves from being reflected back to a receiver.
Although the idea of creating the appearance of invisibility is one which has been in research by many scientists around the world, enhancements into the effectiveness of this technology still has a long road ahead of it. Electromagnetic cloaking experiments began in 2006 and although they were able to achieve the intended result the applications were impractical in the real world. The object intended to be obfuscated would require a complete layer of metamaterials encasing it to produce an invisible property.
The design tested in the experiment can be used on a larger scale utilizing additional loops to obfuscate larger objects as well. The idea is generally simplistic creating a shell like encasement around an object with a layer of antennas attached to reflect a radio signature thus cancelling out the objects signature in the receiver. Tests conducted by Professor Eleftheriades require a specific signature to be emitted from the antennas however advanced applications could prove to be more effective allowing the antennas to work as a sensor and transmitter to adjust automatically to different frequencies.
Applications for this technology are most likely going to provide a beneficial tool for the military to utilize for concealment of vehicles, stations and surveillance. Not only can this electromagnetic cloaking device hide an object’s signature, it can also provide more subterfuge by altering the perceived size of an object along with its location. Further research into these antennas seek allow concealment not only radio waves but light and Terahertz radiation.
The term metamaterial cloaking refers to this general process of using artificial materials (such as plastics and metals) that have a size smaller than the wavelength of the frequency. The objective is to find a negative refractive index which is used to cancel out a signal for the desired wavelength. Research into metamaterials has become one of the newest branches of physics and electromagnetic studies.
Tags: electromagnetic, metamaterials