【作者】 袁宏伟；

【导师】 龚书喜；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2009， 博士

【摘要】 本文针对天线RCS计算方法和机载天线RCS计算两个研究方向,以目标的电磁散射计算和天线隐身技术为研究对象,分别针对电大尺寸目标散射的精确快速计算和微带天线RCS预估和减缩方法进行了研究。取得的成果归纳如下:1.阵列天线RCS计算方法研究。在基本电磁散射计算的基础上,应用了基于矩量法的快速算法—综合函数矩量法(SBF)来计算阵列天线的散射问题。综合函数矩量法解决了传统矩量法由于计算机硬件系统的限制,对于精确求解阵列天线散射存在的内存和速度两方面问题。该方法首先对阵列天线进行模型分块,在模型的每一分块上进行三角面片的网格剖分,并求出每一块上的综合基函数—RWG基函数的线性叠加。综合基函数的获得使计算未知数大幅度减少,从而减少了内存占用和提高运算速度。2.自适应积分(AIM)精确分析电大尺寸目标的散射。详细推导了基于矩量法的另一种快速算法—自适应积分(AIM),并介绍了整个算法流程的关键问题。利用该方法加速求解了电大尺寸目标的散射分析速度并降低储存量,从而提高了现有计算机硬件条件对电大尺寸问题的处理规模和能力。在矩阵与矢量相乘时,采用双共轭梯度法(BICG)改进了求解矩阵方程的方式,进一步提高了程序的运算速度。3.电大尺寸目标散射的自适应积分并行计算。为了进一步提高求解问题的规模,可对自适应积分算法采用并行计算技术。并行计算的关键点是针对自适应积分的具体并行化过程,包括对阻抗矩阵填充和双共轭梯度迭代求解部分进行并行处理,以达到各进程的高并行效率和负载均衡,使求解规模扩大的同时也提高了计算速度。论文分析了电大尺寸的散射算例,计算结果表明了自适应积分并行计算的优越性。4.微带印刷振子天线的散射分析。对于天线隐身技术研究的重点内容,首先引入一种包含馈电结构的微带印刷振子天线散射分析方法。主要目的是用来分离带有馈电结构的微带印刷振子天线的结构模式项散射和天线模式项散射。利用在参考面处设置开路和短路,可以计算在任意负载情况下的结构模式项散射和天线模式项散射。最终分离了任意负载下微带印刷振子天线的散射,明确了散射的根本来源,为微带印刷振子天线的RCS减缩提供理论基础。5.微带印刷振子天线及其阵列RCS减缩研究。研究重点在于微带印刷振子天线及其阵列的宽带化和低散射特性。首先分析了基本天线单元的辐射和散射特性,针对基本天线单元的带宽缺陷提出了用PBG结构来改善其带宽性能,实现了单元的宽带化。其次,根据基本单元天线的散射特性,提出了在地板上采用平面PBG结构来对天线单元进行RCS减缩。最后设计的4×2宽带印刷振子阵列天线既拥有良好的辐射性能,又具有低RCS特性,对微带印刷振子天线的RCS减缩研究具有重要的意义。6.微带贴片天线RCS减缩方法研究。主要是针对微带贴片天线及其阵列的RCS减缩研究。首先引入微带贴片天线开槽方式对单元进行RCS减缩,并详细讨论其散射减缩的基本原理。其次引入贴片阵列天线散射减缩的新方法——贴片天线单元渐变开槽方式。通过对不同的单元开不同尺寸的槽,在等幅度馈电的情况下实现远区辐射场的低副瓣特性。该方法不仅实现了远区辐射场的低副瓣,而且又兼顾了结构模式项散射场的RCS减缩,从而有效的实现了阵列天线的低RCS特性。最后在理论推导的基础上,设计出1×9贴片阵列天线,实验证明了该方法的正确性和实用性。更多还原

【Abstract】 Being associated with two research projects, this dissertation is mainly concerned with the electromagnetic computation of targets and stealth techniques for microstrip antennas. Fast and precise scattering computation algorithms for electrically large targets and methods for antenna RCS prediction and reduction are studied. The author’s major contributions are outlined as follows:1. Research on array antenna RCS computation. Based on the fundamental theory of electromagnetic computation, the method of synthetical basis function (SBF) is proposed as a fast algorithm of MoM to compute the array antenna scattering. The memory and time limitation of traditional MoM in terms of PC hardware is avoided. Firstly the array antenna is divided into blocks, and each block is subdivided into triangle facets. Secondly the sum of RWG base functions on each block is obtained, which can reduce the number of unknowns thus accelerate the computation speed.2. Precise scattering analysis of electrically large targets by use of AIM. As another fast algorithm of MoM, AIM is deduced in detail. The algorithm improves the scattering computation ability by reducing the storage quantity. The solving method of matrix equation is improved by introducing BICG, which increases the computation speed to a further extent.3. AIM parallel computation for scattering of electrically large targets. In order to enlarge the scale of problem, the AIM parallel computation technique is utilized. The critical point is the parallel modification of impedance filling process and the solving process using BICG. This dissertation analyzed the scattering of electrically large targets and results show the superiority of AIM parallel computation.4. Scattering analysis of microstrip printed dipole antenna. A scattering analysis method of the microstrip printed dipole antenna is introduced. The main aim is to decompose the structural mode scattering and antenna mode scattering of the microstrip printed dipole antenna with feeding structure. The structural mode scattering and antenna mode scattering of antennas loaded arbitrarily can be calculated by setting open and short circuits at the feed point. The scattering of microstrip printed dipole antennas loaded arbitrarily is decomposed, which is the base of RCS reduction of microstrip printed dipole antennas.5. RCS reduction analysis of microstrip printed dipole antennas and arrays. Attention is focused on the broadband and low scattering performances. Firstly the radiation and scattering characteristics of element antenna are analyzed. The PBG structure is introduced to improve the bandwidth of the element antenna. Secondly, the ground size reduction method is proposed according to the scattering performance of the element antenna. Finally a4×2broadband printed dipole array antenna designed using this method has both a favorable radiation performance and low RCS.6. Research on microstrip patch antenna RCS reduction technique. Attention is mainly focused on the RCS reduction of microstrip patch antenna and array. The principle of scattering reduction is discussed in detail. A novel theory of patch antenna array scattering reduction which is named patch antenna element gradually changed slotting is introduced. Slots of different sizes are carried out for different elements, which can realize the low sidelobe characteristic of far field when the array elements are fed uniformly. This technique not only realizes the low sidelobe characteristic of far field, but also realizes the RCS reduction of structural mode scattering into account. On the basis of theory analysis, a 1×9 patch antenna array is designed and experiments show the correctness and practicability of the technique.更多还原