Abstract
Transformation optics provides a bridge between the electromagnetic functionality of the device and the material properties of the custom-engineered media. This chapter includes an overview of transformation optics theory and their application in antenna engineering. The basic theory of transformation optics is analyzed, including the general transformation and quasi-conformal mapping. Reviews are focused on the planar lens antenna, the multibeam antenna, the Luneburg lens antenna, and the metasurface Luneburg lens.