Research On Asymmetric Transmission Utilizing Composite Metamaterial

Electromagnetic metamaterial (EMM), regarded as a novel artificial electromagnetic (EM) material whose EM parameters can be manually arbitrarily manipulated, has gain a lot of extraordinary properties which cannot be obtained from natural materials. It is widely concerned and investigated in recent decades. Based on EMM, a lot of novel devices have been proposed, which covers several frequency ranges and have been applied to many domains, including military and communication techniques. Among them, utilizing EMM to realize asymmetric transmission (AT) can get rid of traditional bulky static magnetic field biasing, which leads to the abilities of integration and miniaturization of AT EM devices. Therefore, it becomes a potential and practical investigation area.This thesis focuses on the approach of utilizing EMM to realize AT properties through theoretical analysis, simulating calculation and experimental measurements. AT devices with potential applications in defense detection, electromagnetic compatibility and polarization manipulation are proposed in the paper. The contents are arranged as:1. We make analysis on the realization condition of AT based on transmission matrix theory and summary on transmission matrix forms of standard EMMs structures with mirror or rotation symmetry.2. We propose a one-way absorber for linearly polarized electromagnetic wave utilizing composite metamaterial. The energy of certain linearly polarized electromagnetic wave can be absorbed along one particular incident direction, but will be fully transmitted through the opposite direction. For the cross polarized wave, the direction dependent propagation properties are totally reversed. A prototype is verified through both full-wave simulation and experimental measurement and it achieves desired asymmetric transmission property. The factor that affects the working performance of composite metamaterials is also investigated and the influence from the compositing distance on the absorption curve of the one-way absorber is also investigated and analyzed.3. We propose a reciprocal composite metamaterial device which can mimic the nonreciprocal property of Faraday rotation. The designed device can achieve 90° polarization rotation for the incident linearly polarized EM wave and the rotation direction is irrelevant to propagation direction of the incident wave, but depends on the direction of the incident polarization. Full-wave simulation is carried out to verify the performance of the proposed device, and through further analysis the results are coincident with the ideal.