电磁周期结构设计及其应用

发布时间：2018-01-10 00:32

本文关键词：电磁周期结构设计及其应用　出处：《华侨大学》2017年硕士论文　论文类型：学位论文

【摘要】：平面电磁周期结构发展至今,已研究出多种类型结构如频率选择表面、电磁带隙结构、高阻表面等。现如今由于其独特的电磁特性被广泛地应用于微波领域。基于电磁周期结构的基础理论,本文研究了应用于天线罩的双环型FSS、微波吸波层和MIMO天线的新型周期解耦结构。具体工作内容概括如下:1、设计了一种紧凑的贴片型(带阻型)FSS,其周期单元由双环及连接贴片构成。通过对方形环的等效电路进行分析,合理分布金属贴片的位置,使得频率选择表面具有较小的周期尺寸,能够较好地抑制高阶模的产生,并增加插入损耗。利用HFSS软件对该频率选择表面进行优化,对不同角度的入射波进行仿真,结构体现出较好稳定性。最后通过实验测试,所得结果与仿真结果较为吻合,-15dB插入损耗覆盖整个L频段。2、提出了一种基于宽频带天线理论设计吸波层的方法。根据接收天线与吸波结构工作原理的相似性,选取了一种磁电偶极子宽频带天线为原始模型。以吸波层的吸波原理为理论依据,对宽频带接收天线进行改进,并运用HFSS软件仿真与优化,得到了一种厚度薄且吸波频段宽的新型吸波层。加工与测试结果表明6×6单元吸波层10dB吸波带宽为1.54GHz至3.31GHz,相对带宽为73%,其厚度低于工作频段中心频点自由波长的1/9。由于所设计的吸波层结构具有对称性,它可以工作在双极化条件下。3、设计了一种基于锥形缝隙天线单元的MIMO天线,采用半椭圆型微带线的渐变结构,实现了UWB(3.1-10.6 GHz)功能。通过在地板刻蚀两组对称的缝隙,实现了对WiMAX(3.4-3.7 GHz)和WLAN(5.15-5.85 GHz)的陷波功能。另外,将一对倒L型缝隙作为解耦结构置于两个天线单元之间,测量结果显示在工作频段内天线的?S21?-20dB。为了进一步提高MIMO天线的隔离度,在本文设计的微波吸波层单元结构的基础上,提出了一种适用于MIMO天线的新型周期解耦结构,该周期结构使天线的?S21?低于-25dB。
[Abstract]:With the development of planar electromagnetic periodic structure, many kinds of structures, such as frequency selective surface and electromagnetic band gap structure, have been developed. Due to its unique electromagnetic characteristics, it is widely used in the microwave field. Based on the basic theory of electromagnetic periodic structure, this paper studies the dual-loop FSS used in radome. A novel periodic decoupling structure of microwave absorbing layer and MIMO antenna is presented. The detailed work is summarized as follows: 1. A compact patch type (band-stop FSS) is designed. By analyzing the equivalent circuit of the square ring and distributing the position of the metal patch reasonably, the frequency selective surface has smaller cycle size. It can restrain the high-order mode and increase the insertion loss. The frequency selective surface is optimized by HFSS software, and the incident wave at different angles is simulated. The structure shows good stability. Finally, the experimental results show that the results are in good agreement with the simulation results. The insertion loss of 15 dB covers the whole L band. 2. A method of designing absorbing layer based on broadband antenna theory is proposed, and the similarity between receiving antenna and absorbing structure is presented. A kind of magnetoelectric dipole broadband antenna is selected as the original model. Based on the absorbing theory of the absorbing layer, the broadband receiving antenna is improved, and the simulation and optimization are carried out by using HFSS software. A new kind of absorbing layer with thin thickness and wide absorbing band is obtained. The processing and testing results show that the absorption bandwidth of the 6 脳 6 unit absorbing layer is 1.54GHz to 3.31GHz. The relative bandwidth is 73 and its thickness is less than 1 / 9 of the free wavelength at the central frequency point in the operating frequency band. Because the structure of the absorbing layer designed has symmetry it can work under the condition of double polarization. A kind of MIMO antenna based on tapered slot antenna element is designed, which adopts a semi-elliptical microstrip line with a gradient structure. The UWB(3.1-10.6 GHz) function is implemented by etching two sets of symmetrical gaps on the floor. The notch function of WiMAX(3.4-3.7 GHz and WLAN(5.15-5.85 GHz is realized. A pair of inverted L-shaped slots are placed between two antenna elements as decoupling structures, and the measurement results show the antenna in the working frequency band. S21? In order to further improve the isolation of MIMO antenna, a novel periodic decoupling structure suitable for MIMO antenna is proposed based on the microwave absorbing layer unit structure designed in this paper. The periodic structure of the antenna? S21? Less than -25 dB.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN820

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