【作者】 宗显政；

【导师】 聂在平；

【作者基本信息】 电子科技大学 ， 电磁场与微波技术， 2008， 博士

【摘要】 为实现功能的多样化,越来越多的天线被架设到装备平台上,系统也变得更为复杂。天线与平台之间的相互耦合不仅影响天线本身的性能,同时也影响到系统整体的电磁兼容特性、电磁隐身特性、空气动力学特性等等。因此平台与天线一体化建模分析的重要性逐渐体现了出来。在具体的工程应用中,为降低平台载荷、减少天线数目,有效的宽带/超宽带天线被放到一个显著的位置;另外,弹载/机载平台天线的共形或共口径研究等也被提到了日程上来。本文的工作正是基于上述背景而开展的,研究内容不仅包括平台天线的一体化电磁建模技术,还包括应用需求极强的工程设计。所涉及到的方法不仅有精确的积分方程方法、高效的混合/近似方法,还包括实验测试、缩比模型等方法。围绕平台天线一体化建模的数值方法,本文首先以矩量法为基础,考查了基本流程,分析了其中的关键技术,也给出了在电小或谐振尺度平台下天线问题的实例。在涉及到馈电区几何/电磁建模的细节时,提出了“线簇—面”型及“角—面/角”型单点连接基函数,优点是能够节省未知量、加快求解时间。为提高求解效率,进一步研究了混合的电磁场迭代方法及(多层)快速多极子方法。这些方法,特别是后者,不仅具有精确性、同时具有显著的高效性。对于(多层)快速多极子方法,本文不仅研究了其用于电大PEC平台天线建模的详细过程,同时还将其应用于金属—介质复合平台上的天线仿真。所给出的验模及应用实例也都具有较强的针对性。平台天线问题实际上具有显著的特点,即局部或本地特性。基于这个特点,一些混合或近似方法可被利用以节省计算量、提高求解效率。本文主要考查了平台远端边界硬截断、忽略平台中远区互耦的矩量法—物理光学混合方法、新型相位基函数在辐射问题中的应用、考虑有耗地面影响的格林函数平面波反射系数修正法等。这些方法的有效性在与精确结果的对比中得到了很好地体现。舰载短波/超短波全向超宽带通信天线的设计是本文基于实验研究方法的一项重要工程实践。在综合现有天线宽带技术的基础上,本文采用结构复用、双端馈电、套筒匹配、分布参数优化等手段设计出的新型双馈组合式笼锥超宽带舰载通信天线在超过30个倍频的带宽内实现了很好的匹配,而所需尺寸却较国内外同类型参考天线表现出明显的优势,因而在实用上更具竞争力。本文还在真实的弹载介质罩下研究了很具挑战性的定位+遥测、定位+引信两个双天线共口径方案。将传统的四绕螺旋天线加以改进并作为定位天线,遥测天线考查了环形地板上的单极振子及二元阵列,而引信天线简单地采用以腔壁为地的水平单极振子。通过实验详细研究了口径尺寸及互耦对天线性能的影响,最终的布局方案能很好地实现定位天线口径法向右旋圆极化辐射、遥测天线口径面线极化掠射及引信天线的法向线极化辐射,各自的带宽也得到了满足。虽然所作工作还较为粗浅,然而已在平台天线一体化建模及实验探索方面形成了大概的轮廓,已经具备了精确求解电大复杂平台天线辐射问题的能力,为将来的研究打下了较好的基础。两项工程设计均具有很好的技术性能及应用前景,目前已经开始向实用化方向努力。更多还原

【Abstract】 More and more antennas are being mounted on weapon platforms for multifunction, and armament systems become more complex. The mutual couplings between the antennas and the platform affect not only the parameters of the former but also the other characteristics of the whole system including electromagnetic compatibility, low observability, and aerodynamics, etc. Hence, the importance of the integrative platform-antenna modeling and analyzing gets more evident. In actual engineering, to decrease the platform load and the antenna number, efficient wideband/ultra-wideband antennas have been put on an important position; in addition, co-aperture or conformal studies for onboard antennas have also been recorded in calendar.The work in this paper is carried out based on the above mentioned backgrounds; its content includes some integrative electromagnetic modeling techniques and also some engineering designs according to urgent requirements. The involved methods include rigorous integral equation methods, high efficient combined/approximate algorithms, experimental testing and scale model methods, etc.Surrounding the integrative numerical modeling, this paper firstly takes the moment methods as a foundation. The main process of this approach is shown, some key techniques are analyzed, and several examples of antennas mounted on electrically small or resonant platforms are given out. When emphasis focused on the details of the geometrical/electromagnetic modeling of the antenna feed regions, two new-typed wires-to-surface and pyramid-to-surface/pyramid junction bases are presented, which enjoys the benefits of decreasing unknowns and accelerating solving speed.To improve computational efficiency, the hybrid electromagnetic iterative methods and the fast multipole method (or multilevel fast multipole algorithm, MLFMA) are further studied. These two categories of methods, are accurate and high efficient. For the MLFMA, its detailed process in the modeling for problems of antennas mounted on electrically large PEC objects and also its applications in dielectric-metal combined platforms are studied in this paper. All the examples for demonstration are pertinent.Platform-antenna problems have distinct characteristics, namely the localized or restricted features. Some hybrid or approximate methods based on these characteristics can be adopted to save computational cost and increase solving efficiency. In this paper, the emphases are mainly put on the truncations of the far ends of the platforms, the hybrid moments-physical optics methods in which the mutual couplings between the elements of the middle/far regions of the platforms are ignored, the applications of the new-typed phase-extracted basis functions in radiation problems, and the modification to the Green’s function by plane-wave reflection coefficients when considering the effects of lossy grounds. The efficiencies of these methods are well confirmed by the comparisons between their results with those obtained through accurate methods.The design of the shipboard shortwave/ultrashort ultra-wideband communication antenna in this paper is an important engineering practice based on experiment methods. With the aid of some existing wideband techniques, a new-typed dual-feed combined cage/cone-shaped ultra-wideband antenna for shipboard omnidirectional communication has been designd successfully though the integration of structure combining, dual-port feeding, sleeve matching, and distributed parameter optimizing. The proporsed antenna has a good impedance match in a bandwidth larger than 4.9 octaves, and its geometrical dimensions are much smaller than those of the internal/external congeneric ones, so it is more preponderant in practicality.Two very challenging co-aperture arrangements of dual antennas for orientation plus telemetry or orientation plus fuze are proposed under actual missile-board dielectric radomes in this paper. A traditional quadrifilar helix is improved to act as the orientation antenna, a single monopole or a two-element array mounted on a ring-shaped ground are adopted to suit the telemetry role, while the fuze antenna is simply made of a horizontal monopole threaded out of the inner wall of the cavity. The effects of the aperture dimensions and the mutual couplings on the antenna performances are analized through a large number of experiments. A right-hand circular polarized radiation normal to the aperture surface for the orientation antenna, a radiation in the grazing direction of the aperture surface for the telemetry antenna, and a linear polarized radiation normal to the aperture for the fuze antenna are simultaneously and well realized in the final arrangements, and the bandwidth requirements for these antennas are also met.Although the work might be some superficial, it has formed a rough profile about the integrative modeling and the experimental investigating methods for platform-antenna problems. At the same time, it has formed the capability to analize radiation problems of antennas on electrically large and complex platforms and also formed a good base for future studies. The two engineering designs both have good electric performances and application foregrounds and are being put forward with great efforts.更多还原