Metamaterial-Based Slab Lenses And Their Applications

As a kind of artificially-designed material composed of a series of sub-wavelength unit cells, metamaterial has unique electromagnetic properties which can't be realized by natural materials. By tailoring the metamaterial unit cells, arbitrary permittivity and permeability can be achieved, which means electromagnetic waves can be manipulated flexibly. Therefore metamaterial catches many attentions and many related achievements have been made in different fields. In this thesis, we focus on the metamaterial lenses, and apply lens antennas to different practical engineering systems. The main contents of the thesis are as follows:1. The main design principles of metamaterial lenses antennas are reviewed, including the geometric optics and effective media theory. Two kinds of lens antennas based on different theories are designed to improve the directivity of a traditional circular-patch antenna. One is zero-index lens and the other is gradient-index lens. Both are simulated and experimentally realized with different unit cells. The experimental results show that both lenses improved the directivity of circular-patch antenna and gradient-index lens antenna has a better performance with higher directivity, which match well with the simulations.2. A focusing lens based on gradient-index metamaterial is designed and applied to practical engineering backgrounds, including the radome IPD measurement system and biomedical science. The focusing lens is modeled and simulated. The result shows that a small focal spot can be realized in a long focal distance.3. A mechanically scanned lens antenna based on gradient-index metamaterial is designed and analyzed. By changing the relative position of the feed and the lens, a wide scanning range can be realized. The simulation results of near field and far field of the beam scanning lens antenna show a highly directive main lobe and low side lobe level.