Novel Microstrip Antenna Design Upon Transformation Medium

In this letter, the substrate of a microstrip antenna is chosen as the transformation medium. Using complex transformation optics, a standing-wave current distribution along the circumference of a circular patch is transformed into a uniform traveling current distribution instead, thus generating perfectly circularly polarized waves. This letter provides a novel way of designing the microstrip antenna whereby the traditional substrate is replaced by the transformation medium whose parameters can be readily derived from the theory of transformation optics. Furthermore, introducing complex transformation optics into antenna design is a new attempt. In terms of its flexibility of controlling the amplitude distribution of electromagnetic fields, it offers extra freedom of manipulating the radiation pattern of an antenna.