【作者】 常雷；

【导师】 廖成；

【作者基本信息】 西南交通大学 ， 电磁场与微波技术， 2013， 博士

【摘要】 超宽带天线是超宽带无线系统中不可缺少的重要组成部分,超宽带技术能够广泛应用于雷达、定位、探测及控制等领域,天线无疑承担了很重要的的角色,也使得超宽带天线及阵列成为了近年来的研究热点以及超宽带技术中的重要研究方向之一。本文的研究围绕着超宽带天线及阵列的快速设计方法展开。在对电大尺寸的超宽带天线及阵列进行全波模拟时计算时间长、占用内存大,甚至一台电脑有时都无法进行仿真,为了解决这个问题,本文基于并行自适应结构网络应用支撑软件框架(JASMIN)研究了适用于大型并行平台的高效并行时域有限差分(Finite-Difference Time-Domain,FDTD)法。首先研究了均匀网格并行FDTD方法及其关键技术,对其正确性进行了验证,并采用500个处理器核对144单元TEM喇叭及加脊TEM喇叭天线阵进行了仿真计算；接着研究了渐变非均匀并行FDTD方法,可以有效解决天线及阵列结构中存在细微结构时均匀网格内存需求和计算量大的问题,采用此并行算法在200个处理器核上模拟了64单元螺旋天线阵列的辐射特性；最后,为了快速求解具有旋转对称结构的天线辐射问题,研究了并行旋转对称FDTD方法,实现了对主反射面直径为280个波长的标准卡塞格伦天线的并行计算。同时超宽带天线及阵列中涉及到的参数较多,且参数与设计目标之间的关系是非线性的,因此有必要引入全局优化方法对其进行辅助设计,而优化算法的性能将直接影响天线与阵列的性能以及设计所需要的时间。为了提高全局优化算法的性能,首先研究了并行微遗传算法(Micro Genetic Algorithm,MGA).并行整数编码微分进化策略(Differential Ecolution Strategy,DES),将粗粒度和细粒度并行MGA、整数编码DES应用于32元对称线阵的方向图综合问题,证明了其性能优于串行优化算法和文献中提出的DES；接着研究了基于DES和连续蚁群优化(Continuous Ant Colony Optimization,CACO)算法的混合改进算法—HDECACO,通过对两个典型数学函数的优化,证明了改进算法的高效性。随后论述了本文提出的并行全局优化算法和HDECACO算法对超宽带喇叭天线的优化设计。将并行全局优化算法与三维均匀网格并行FDTD结合,实现了TEM喇叭天线的自动优化,进一步证明了并行MGA更能保持种群的多样性,搜索能力更强；为了设计出高效的反射而天线的馈源,对多模圆锥喇叭天线进行了研究,提出了旋转对称FDTD算法与全局优化算法相结合的自动优化设计方案,并应用HDECACO算法对半径突变和多节变张角圆锥喇叭天线进行了优化设计,验证了方案的可行性；采用细粒度并行MGA优化设计了工作在8-13GHz的波纹多模圆锥喇叭天线,在整个工作频带内,边缘照射电平、增益和主瓣宽度等指标都具有较好的恒定值,而且电压驻波比小于1.5.其后对平面超宽带(Ultra-wideband, UWB)天线及功分器进行了研究。针对平面UWB天线中涉及到的热点研究方向展开了研究,首先提出了一款新颖的带宽增强型微带天线,具有双频带的工作特性,覆盖了2.1～2.6GHz和3.3～20GHz频段；而UWB频段会对其它无线通信系统产生干扰,为了解决这一问题,研究了具有陷波功能的UWB微带天线,提出了一种开路环谐振器结构和U形结构,均可以实现双频段陷波功能,与常用的多陷波天线实现方法不同；也考虑了UWB平面定向辐射天线的应用需求,采用基于指数曲线和椭圆曲线的混合渐变线方法,实现了Vivaldi天线的小型化设计,并借鉴了这种技术,采用粗粒度并行MGA与商业电磁软件结合对功分器进行了优化,获得了比文献中的结果更好的一款UWB功分器；最后,还采用HDECACO方法与传统DES、CACO算法优化了一款超宽带E形贴片天线,进一步证明了混合优化算法的优越性。最后将并行MGA和HDECACO算法应用于超宽带天线阵列的优化问题。首先采用主从式并行MGA优化了含有49个单元的TEM喇叭天线阵,在200处理器核上通过并行FDTD方法求解了适应度值,减少了优化所需的时间；其次将有源单元方向图技术用于天线阵列的分析,可以考虑天线单元间的互耦,得到的阵列方向图与商业软件全波模拟后的方向图吻合很好,并与提出的全局优化算法相结合,实现了超宽带天线阵列的快速设计：采用HDECACO优化设计了一个8元H面排列的直线超宽带Vivaldi天线阵,优化变量为天线单元的馈电幅度,其激励相位相同,与等幅度和-30dB切比雪夫激励阵相比,优化后的副瓣电平明显降低了；以E形贴片天线为单元,采用细粒度并行MGA,对矩形栅格排列(256个天线单元)和三角形栅格排列(200个天线单元)平面阵的馈电幅度,以及4圈同心圆环平而阵(60个天线单元)的馈电幅度和相位进行了优化设计,有效的减少了优化所需的时间,并获得了较好的优化结果。更多还原

【Abstract】 The ultra-wideband (UWB) antenna is an important and indispensable component of UWB wireless systems. The antenna undoubtedly plays a very important role for the UWB technology widely used in many areas such as radar, positioning, detection and control. So in recent years, the study of UWB antennas and array becomes hot investigation, as well as one of the important research directions in the UWB technology. This paper is mainly focused on the rapid design methods of the UWB antennas and array.The simulation of the electrically large UWB antennas and array needs long time and great memory, and even one computer sometimes can not complete the calculation. In order to solve this problem, some highly efficient parallel finite-difference time-domain (FDTD) methods for the large-scale parallel platform are studied, based on the "J parallel Adaptive Structured Mesh applications Infrastructure"(JASMIN) framework. Firstly, the uniform grid parallel FDTD method and its key technologies are studied and verified. Then the144-element TEM horn and Ridged TEM horn antenna array are calculated using500processors. Secondly, the gradual non-uniform parallel FDTD method is studied, which can effectively decrease memory requirements and computational effort problems by comparison with the uniform grid FDTD method, when the antennas and array have fine structure. Using this parallel algorithm, the radiation characteristics of a64-element spiral antenna array is simulated on200processors. Finally, the parallel body-of-revolution FDTD (BOR-FDTD) method is studied for fast solution of the antenna with rotationally symmetric structure. A standard Cassegrain antenna is parallel computed and the diameter of its main reflector is280wavelengths.The UWB antennas and array involve many parameters, as well as the relationship between the parameters and design goals is nonlinear. Therefore it is necessary to introduce global optimization algorithms for antennas and array aided design. The performance of optimization algorithms will directly affect the performance of the antennas and array, as well as the design time. In order to improve the performance of global optimization algorithms, the parallel micro genetic algorithms and integer coded differential evolution strategies are first studied. The coarse-grained and fine-grained parallel MGAs, integer coded DESs are applied to a32-element linear array pattern synthesis problem. It is shown that performance of the parallel algorithms is better than the serial optimization algorithms and the DES proposed in a literature. Then a hybrid optimization algorithm (HDECACO) based on DES and continuous ant colony optimization (CACO) algorithm is proposed to improve the search ability. Two representative mathematical functions are minimized using the HDECACO algorithm and the convergence rates are compared to prove its high efficiency.Subsequently, the proposed parallel global optimization and HDECACO algorithms focusing on the design of UWB horn antennas are discussed. The parallel optimization algorithms and the3-D uniform grid FDTD method are combined to achieve an automated parallel design process for TEM horn antenna. The results show that the parallel MGAs can be better to maintain the population diversity, and have stronger search ability. In order to design high efficient feeds for reflector antennas, the multimode conical horn antennas are studied. The automatic optimization design with combination of BOR-FDTD and global optimization algorithms is proposed. The HDECACO algorithm is applied to optimize the multimode conical horn antennas with a step of radius and multi-section changing flare angles. The feasibility of automatic design is verified And then the fine-grained parallel MGA is used to design a corrugated conical horn antenna in the8-13GHz. In the entire operating band, the tapered edge irradiation, gain and main lobe width have preferably constant values, and the voltage standing wave ratio is less than1.5.Thereafter, the paper studies the planar ultra-wideband (UWB) antennas and power divider. The hot research directions related to planar UWB antennas is carried out. A novel compact ultra-wideband planar antenna fed by a microstrip line is proposed. It has been demonstrated that the proposed printed compact antenna can achieve a good impedance bandwidth,2.1-2.6GHz and3.3-20GHz. Within the whole UWB band (3.1-10.6GHz), there still exist several narrow bands for other communication systems,, which may cause severe electromagnetic interference to the UWB system. Therefore, it may be necessary to have a notch for those bands in order to avoid potential interference. In this paper, two new simple dual band-notched printed antennas with variable frequency band-notch characteristic are proposed, unlike the commonly used methods. Only by using the split ring resonator and U-shaped parasitic elements on the back side of the radiation patch, two desirable operating bands can be achieved for the proposed antennas. The application requirements of UWB planar directional radiation antennas are also considered here. A tapered microstrip line comprising exponential and elliptic sections is applied to achieve the UWB performance and miniaturization design for the Vivaldi antenna. By using this technology, an UWB power divider is designed, which is optimized by the combinatorial method of the coarse grained parallel PMGA and a commercial electromagnetic software. The optimized power divider exhibits better performance. Finally, The HDECACO algorithm is applied to design an E-shaped wideband patch antenna, which achieves the impedance bandwidth4.8-6.53GHz. The advantage of this hybrid method over the DES and the CACO is also demonstrated.At last, the parallel MGAs and HDECACO algorithm are applied to UWB antenna arrays optimization problems. Firstly, a49-element TEM horn antenna array is optimized by the master-slave parallel MGA. The fitness values are calculated by parallel FDTD method on200processors, and the optimization time is reduced. Secondly, the active element pattern (AEP) method is used to solve the array radiation problems. The AEP method is very effective because it includes the effects of mutual coupling rigorously for computing the far-field pattern of a fully excited array. The array patterns calculated by this method are in good agreement with the results by the full-wave simulation of commercial software. The UWB antenna arrays can be fast designed by combining with the proposed global optimization algorithms:A8-element H-plane linear UWB Vivaldi antenna array in the same phase is optimized by the HDECACO algorithm. The excitation amplitudes are as the optimization variables. Compared with the uniform amplitude and-30dB Chebyshev antenna array, the side lobe level (SLL) obtained by the optimization algorithm is lower. Using the fine-grained parallel MGA, the excitation amplitudes of the256-element rectangular lattice and200-element triangular lattice E-shaped patch antenna array in the same phase is as the design parameters. To the4-circle60-element concentric circular ring E-shaped patch antenna array, the design parameters to be optimized are excitation phases and amplitudes. The optimization time is effectively reduced, and good results are achieved.更多还原