Transformation electromagnetics in antenna engineering: Theory and implementation

Current designs of electromagnetic cloaks are largely based on the use of metamaterials and a technique called “transformation optics/electromagnetics”. Free space cloaks require materials with extreme properties and, hence, they are difficult to implement in practice. However, the theory of “transformation optics/electromagnetics” offers a useful design tool for antenna engineers, and enables them to develop novel antennas. In this paper, we will review some research activities at Queen Mary, University of London, regarding applications of transformation electromagnetics in the antenna and microwave engineering. Design examples such as flat reflectors, lenses and sub-wavelength antennas will be introduced. Novel FDTD techniques to deal with the design of gradient index metamaterials will be also demonstrated and used to evaluate the performance of transformation-based antennas. In particular, the tradeoff in antenna performance whether or not metamaterials are required in the design will be discussed.