Applications of metamaterials to planar antenna design

Analysis and optimization of antennas on metamaterial-loaded substrates/superstrates are considered in this work. The applications of metamaterials include: increasing the antenna bandwidth, miniaturization, improving antenna coupling efficiency, and the formation of narrow beam radiation patterns are considered in this work.; The analysis of metamaterial-loaded antennas based on the electromagnetic properties of the effective medium is proposed. These effective medium parameters are retrieved from waveguide or free space structure simulations. Dispersive Finite Difference Time Domain (FDTD) implementations are used to simulate the reaction of, and mutual coupling and radiation from the antenna structures. Electromagnetic simulations are performed for both the discrete structure representations of the layered metamaterials embedded in a simple dielectric substrate and their dispersive effective medium representations. Effects of metamaterial anisotropy and chirality on the antenna return loss and radiation pattern are also investigated. Besides FDTD, the periodic Green's function method is used to calculate the electromagnetic responses of metamaterial structures, and effects of inclusion density, mutual coupling and other perturbations are investigated.; An iterative optimization method is then applied to determine the most suitable parameters of the metamaterial for a given objective function. In the studied antenna configuration, the substrate of the antenna is primarily responsible for the improvement of the radiation efficiency while the role of the superstrate is to provide narrow-beam radiation pattern due to the use of anisotropic near-zero refractive index metamaterial. Numerical examples that illustrate metamaterial applications are provided.