基于梯度折射率透镜的波达方向估计技术研究

发布时间：2018-01-25 23:19

本文关键词： 无源探测定位波达方向估计梯度折射率透镜电磁谐振器高阻抗电磁表面　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：作为无源探测定位技术的核心，波达方向估计技术有着极其广阔的应用前景。但传统的波达方向估计技术为了获得较为精确的结果，通常都会在系统前端设置数量众多的天线阵元，这就使系统的构造复杂体积庞大，制造和维护成本较高，从而制约了波达方向估计技术的实际应用。龙伯透镜作为梯度折射率透镜的一种实现小型化的形式，可以将入射的平面波汇聚到透镜边缘的一个焦点上，非常适合作为多波束天线。本文利用梯度折射率透镜的特殊电磁特性，将其应用到波达方向估计技术中，减少系统所需接收天线的数量要求，降低成本和算法难度。本文的主要内容可分为如下几部分：首先，本文基于等效媒质理论，通过推导得出了利用S参数提取等效电磁参数的方法。提出了一种新型的立体十字型结构作为梯度折射率超材料的单元，并计算出了其结构尺寸与电磁参数的对应关系。在此基础设计出三维结构的梯度折射率透镜。仿真结果表明，在平面波入射情况下，该透镜在X波段能够实现良好的汇聚效果。其次，本文将电磁谐振器引入到梯度折射率透镜的设计中来。利用电磁谐振器在低于谐振频率时，其等效电磁参数基本保持一致的特性，通过仿真计算得到了其电磁参数随结构尺寸的变化规律。在此基础上设计出了低剖面型的二维结构的梯度折射率透镜。此外还提出了一种基于高阻抗电磁表面的梯度折射率透镜，通过调整表面波阻抗来控制电磁波的传播路径。由于利用PCB制作工艺即可完成制作，具有透镜制作成本较低、体积小的特点。最后对波达方向估计进行算法的设计。由于梯度折射率透镜可以很好的将电磁波汇聚到一点，因此可以通过最大信号法来实现对波达方向的测量。在透镜边缘放置信号接收装置，旋转透镜的同时检测接收到的信号幅度，当幅值最大时，，接收装置和透镜中心所指向的方向就是波达方向。该算法简单易行，而且仿真和实际测量结果显示其精确度较高。
[Abstract]:As the core of passive detection and location technology, DOA estimation technology has a very broad application prospects, but traditional DOA estimation technology in order to obtain more accurate results. Usually, a large number of antenna elements are set in the front end of the system, which makes the structure of the system complex and huge, and the cost of manufacturing and maintenance is high. Therefore, the practical application of DOA estimation is restricted. As a miniaturized form of gradient index lens, Lomber lens can converge the incident plane wave to a focal point on the edge of the lens. It is very suitable as a multi-beam antenna. In this paper, the gradient index lens is applied to the DOA estimation by using the special electromagnetic characteristics of the gradient index lens, which can reduce the number of receiving antennas required by the system. The main contents of this paper can be divided into the following parts: Firstly, based on the theory of equivalent medium, the method of extracting equivalent electromagnetic parameters by using S parameters is derived, and a new type of stereoscopic cross structure is proposed as the element of gradient index metamaterials. The corresponding relationship between the structure size and electromagnetic parameters is calculated. On this basis, the gradient index lens of three-dimensional structure is designed. The simulation results show that the incident plane wave is the case. The lens can achieve a good convergence effect in X band. Secondly, the electromagnetic resonator is introduced into the design of the gradient index lens. The equivalent electromagnetic parameters of the electromagnetic resonator are basically consistent when the resonance frequency is lower than the resonant frequency. The variation of electromagnetic parameters with structure size is obtained by simulation. Based on this, a low profile gradient refractive index lens with two-dimensional structure is designed. In addition, a kind of high impedance electromagnetic surface based gradient index lens is proposed. Gradient index lens. The transmission path of electromagnetic wave can be controlled by adjusting the surface wave impedance. Because the fabrication process can be completed by using PCB, it has the characteristics of low cost and small volume of lens fabrication. Finally, the algorithm of DOA estimation is designed. Because the gradient index lens can converge the electromagnetic wave to a point well. Therefore, the maximum signal method can be used to measure the direction of arrival. A signal receiving device is placed at the edge of the lens, and the amplitude of the received signal is detected while rotating the lens, when the amplitude is the largest. The direction of the receiver and the center of the lens is the direction of arrival. The algorithm is simple and feasible, and the simulation and actual measurement results show that the accuracy of the algorithm is high.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN95

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