Application of transformation electromagnetics for omnidirectional emission

A directional directive emission is converted into an omnidirectional one based on the transformation electromagnetics concept. A dipole antenna used as the excitation source is embedded in a bulk metamaterial presenting gradient radial and angular permittivity. Electric-LC resonators are used to produce such gradient permittivity metamaterials. Theoretical analysis is presented and numerical simulations are performed to present the concept. Near-field cartography and far-field radiation pattern measurements are done to validate the proposed omnidirectional antenna. A good agreement is observed between simulations and measurements.