中文摘要：

根据各向异性媒质理论，设计了一种宽带、反射型超材料极化旋转体，能够将线极化波极化方向旋转90°，极化转化率大于90％的工作带宽为5．5—14．5GHz．该极化旋转体由两层介质板、金属双开口谐振环和金属底板周期排列构成，具有各向异性的特点，单元两对角线方向的电场分量反射系数相同，反射相位相差180°，导致其极化旋转特性．利用表面电流分布图，分析不同极化波入射时该极化旋转体的谐振状态，实验和仿真结果符合较好．该极化旋转体在新型天线设计和隐身技术等方面具有广阔的应用前景．

英文摘要：

Polarization is one of the basic properties of electromagnetic waves and is valuable in communication, navigation and radar detecting. So it is important to control and manipulate polarization states of electromagnetic waves. In this paper, we design, fabricate and measure a broadband reflective metamaterial 90° polarization rotator which has a double-split-ring resonator （DSRR） structure, composed of two layers of dielectric and a metal plate ground. The explanation of the physical mechanism of the polarization rotator is presented according to the anisotropy media theory. Anisotropic metamaterials can cause a phase or amplitude difference between two crossed polarization waves, which can be used to manipulate the polarization states of the incident waves. The anisotropic polarization rotator behaves different for two orthogonal axes, and the surface current distributions of the DSRR are discussed to analyse the different characteristics of the structure along two orthogonal axes. The DSRR behaves as a dipole resonator that couples with the electric component along one axes and behaves as an LC resonance circuit that couples with the other electric component. Thus, almost an equal magnitude and a 180° phase difference can be generated between the two orthogonal electric components of the reflected waves. The polarization states of the reflected waves will be rotated by 90°, when incident waves are polarized by 45° with respect to the symmetric axis of the rotator, and it will be retained when the incident waves are circularly polarized. Simulation results show that this device can work with the relative bandwidth of 90% from 5.5 to 14.5 GHz, of which the polarization conversion ratio is larger than 90%. The polarization conversion ratio will decrease as the incident angle increases, but this high polarization conversion ratio can be obtained at several frequencies. A 576-cell （24 × 24） prototype of the polarization rotator has been fabricated using a printed circuit board method on the FR4 substrate