Realization And Simulation Metamaterials By Transmission-Line Network

The emergence of metamaterials provide people a powerful method to manipulate electromagnetic waves. Metamaterials are actually periodical structures made of subwavelength units. According to the effective medium theory, when the dimension of the unit cell is much smaller than the wave-length of free space, it can be regarded as effective medium. In this thesis, we have discussed two types of periodical structure and their applications. One is resonant periodic structure, and the other is non-resonant periodic structure. The main contents of this thesis are listed below:1) We present the design, fabrication, and experimental characterization of a modified two-dimensional Luneburg lens based on I-shaped units, with the focus inside the lens. The experimental results agree well with the simulation results.2) The lumped transmission-line network is used to realize anisotropic zero-index material to arbitrarily control the power flow, and realize the spatial power combination for omnidirectional radiation in two-dimensional case. It is also used to implement optical transformation device which can transform cylinder wave to plane wave. The simulation results are consistent to the results in COMSOL.3) The distributed transmission-line network is introduced, and field averaging method is applied to retrieve effective material parameters. The design of distributed transmission-line network based on any known medium parameters is also discussed.