Research On The Manipulation Of Polarized EM Waves Using Metamaterial

Metamaterials (MMs) have different macroscopic electromagnetic properties that we cannot find in natural materials, which is result from the diversity and flexibility of unit cell with unique electromagnetic response. Using different unit cell with special electromagnetic resonances, we can design MMs response to electromagnetic wave with special devices and to mimic the quantum phenomena. MMs not only expanded the research scope of electromagnetic theory, but also opened a new way to control the electromagnetic wave propagation and design high performance microwave devices.The paper has designed a reflective polarization converter and simulated electromagnetic induced transparency(EIT)for circular polarized wave model based on the MMs. Using the electromagnetic theory, simulation and experiment methods, we analyzed the characteristics of reflected and transmitted wave in polarization converter and EIT model. Results in this thesis can be summarized as follows:1. Designed a new type of reflective polarization converter based on square loop shaped metamaterial. The incident linearly polarized wave will be converted to its cross-polarized state with a polarization conversion ratio (PCR) lager than 90% in two frequency ranges 5.70-8.62 GHz and 13.30-15.70 GHz, the relative bandwidth of 47.75%and 16.78% respectively. In the same way, circularly polarized wave will be reflected to its co-polarized state efficiently in the same spectrum regimes. The experimental results are consistent with the simulation results.2. A three-dimensional metamaterial that can motivate like-EIT for circular polarized wave is designed. That the experimental results are in agreement with simulated verified the correctness of the design. The unit cell consists of a pair of metallic strips printed on both sides of the Printed circuit board(PCB) which are connected by drilled hole inside the substrate. When right circular polarization wave incidents, destructive interference is excited between metamaterial structure unit, and thus one can achieve a sharp transparency window in the transmission spectral. Surface current model, coupled oscillator model and an electrical equivalent circuit model were applied to quantitatively and qualitatively analysis the coupling mechanism of the like-EIT MMs. Meanwhile, the effect of slow wave propagation in EIT and the designing of the refractive-index sensors were discussed.