Device Design And Experimental Study Of Metamaterials

Metamaterials with fascinating electromagnetic properties are composed of man-made periodic or pseudo-periodic unit cells. In this dissertation, we begin with the novel electromagnetic properties of metamaterials, and investigate the potential applications of metamaterials in transparent cloaks, antennas, lens and invisibility fields. Some experiments in the microwave range have been made to show the excellent performance of metamaterial devices. The following aspects are studied:An electromagnetic transparent cloak is designed with transformation optics. Using the transmission-line unit cells, its equivalent circuit model is proposed for the possible realization and then full wave simulation is executed to show its performance.With the help of quasi-conformal mapping, a planar focusing antenna which has similar performances as that of its parabolic counterpart is designed. Then we take the non-resonant1-shaped metamaterial unit cell to realize the planar antenna, whose feature is verified with simulation and experiment. Its application is also discussed in the real antenna system.Based on conformal mapping, a multiple-beam antenna is proposed using isotropic materials, and its performance is confirmed and analyzed by using simulation. A square fish-eye lens is further introduced and its possible implementation is demonstrated with the proven method.According to the theory of geometrical optics, three kinds of gradient-index microwave devices, i.e. deflecting lens, focusing lens and a45-degree waveguide, have been designed and experimentally verified with the drilling-hole metamaterials. Numerical simulation results have an agreement with the experimental results. A directional cloaking device is also introduced using the analogy between geometrical optics and electrostatics. Moreover, the performance of this cloak is analyzed with numerical method. Taking the broadband I-shaped unit cell, a Maxwell half fish-eye lens antenna is designed and then its performance is experimentally measured using a2D mapper. Its possible application in antenna system is also discussed for its3D extended version.Our study shows that metamaterials combining the theory of geometrical optics and transformation optics, have become a powerful method to design the fascinating electromagnetic devices. Deep research on the controllable electromagnetic properties of metamaterials can further enrich the breadth and width of the electromagnetic theory in wave manipulating and controlling. Furthermore, the pursuing for broadband and low loss unit cell will accelerate the practical application of novel electromagnetic devices. With the development of new interdisciplinary study of metamaterials, they will certainly provide the potentials in the science and engineering application field.