论文标题:基于圆柱载体的共形偶极子天线阵性能研究
Research on Performance of Cylindrical Conformal Dipole Array Antenna
论文作者
论文导师 杨莘元,论文学位 博士,论文专业 通信与信息系统
论文单位 哈尔滨工程大学,点击次数 170,论文页数 125页File Size5474K
2007-04-01论文网 http://www.lw23.com/lunwen_161505232/
conformal antenna;; compensating for mutual coupling;; electromagnetic scattering
在电子战与信息战飞速发展的今天，各种先进的飞行器和交通工具(飞机、导弹、卫星、舰船和车辆等)所携带的天线除了要求具有优异的性能之外，更要求天线单元能安装嵌入载体表面，使阵列天线的表面与这些载体表面吻合，共形天线就是在这种情况下定义的。不仅传统的军事工业对高性能的共形天线有着强烈的需求，而且随着移动通讯的飞速发展，共形天线作为基站天线或便携式天线，都有着良好的应用前景。因此，分析研究共形天线的特性具有极其重要的国防意义和工程价值。 共形天线的性能研究是一个非常活跃的研究领域，也是未来电子战争中隐身技术的重要部分。共形天线就其本质而言，是一种要考虑周围环境对其性能影响的天线形式。对天线的建模越接近于其工作的实际环境，就能越精确地预测其工作特性。现阶段共形天线建模及其技术研究主要存在的不足有：理论研究多在理想条件下进行，没有考虑实际载体对天线的影响；分析算法收敛速度慢、耗时大，难以满足对共形天线进一步分析的需求。为此，本文着重对基于圆柱载体的共形偶极子天线阵进行建模并对其分析算法进行研究。本课题的主要研究内容和创新点如下： 本文首先研究了一种应用RWG基函数和偶极矩联合分析平面天线阵特性的方法。该方法利用在偶极子天线模型中，每个RWG基边缘元素上的电流分布都可以由一个无穷小的偶极子天线产生的电流代替，每个小天线具有相同的偶极矩的原理，通过对所有偶极矩产生的电场求和得到阵列的电场。该方法将电场积分方程转化为电场求和运算，因此很大程度上缩减了计算时间，提高了计算效率。 其次，针对电大尺寸共形天线的分析方法收敛速度慢、数值计算不准确的问题，提出了一种依据圆柱载体模型、改进积分路径的Watson变换简化电场公式的方法。该方法根据圆柱载体的特殊结构，利用Watson变换将电场积分路径进行改造，改造后的积分路径缩减了求解电场过程，从而提高了积分计算效率。仿真结果证明，其计算结果与直接积分所得的结果比较，该方法在不影响精度的前提下大大减少了计算的复杂性，缩短了计算时间，可以方便有效地处理复杂结构，具有较强的适用性。 再次，针对现有共形天线理论研究多忽略互耦和没有进行互耦补偿的问题，分别提出了计算互耦和补偿互耦的方法：在计算互耦方法中，提出了一种应用偶极矩的性质修正混合算法计算广义阻抗矩阵的方法，该方法利用偶极矩连接RWG基相邻区域信息的特点，修正混合方法没有考虑不同区域互耦影响的不足；在互耦补偿方法中提出了一种利用接收电压信号进行补偿期望信号，从而得到补偿矩阵的方法，该方法以偶极子天线电流分布相对稳定为前提，将电流分布进行归一化提取，得到互耦影响下的实测电压值，将实测电压值与期望信号电压值进行比较推导出互耦补偿矩阵。因此在互耦特性的考虑上，本文采取双保险，先是计算广义阻抗矩阵方法中计入各“小单元”之间的“互耦”，而后再对广义阻抗矩阵进行补偿。仿真试验表明，互耦补偿效果在很大程度上降低了辐射方向图和RCS的旁瓣效应。 最后，针对共形天线散射特性的建模精度和RCS减缩的问题，本文分别提出了新的共形天线建模方法和RCS减缩技术：在共形天线散射特性的建模方面提出了一种应用非均匀有理B样条理论(NURBS)+MOM混合技术对共形天线进行建模方法，该方法将柱体共形天线分为圆柱载体和天线两个区域分别进行NURBS建模和MOM建模，在很大程度上消除了用平面元近似圆柱载体模型所造成的误差，大大减小了天线周围的曲面个数，从而有利于提高计算速度，该方法在分析散射特性时计入了载体的影响，使算法更具有实际意义；在RCS减缩方面提出了一种加载感应线圈实现RCS减缩的方法，该方法在共形天线馈电处加载可调电感来控制天线的谐振频率，从而控制RCS值，仿真结果证明，该方法在增益影响不大的前提下，在一定程度上降低了天线的RCS值。 综上所述，本论文研究了基于圆柱载体的共形偶极子天线阵的建模及性能，提出了辐射特性、互耦估计及补偿、散射特性和RCS减缩的相应解决方案，仿真结果证实了本文所提出的算法及方案能够获得较好的效果。
With the development of electronic wars and information wars, excellent performances and good matches to carrier surfaces of antenna are required in the application fields of advanced aerocrafts and vehicles(aeroplane、missle、secondary planet、warship and vehicle), and conformal antenna is defined in the circumstances. Not only the traditional military affairs have a great demand for conformal antenna, but also the mobile communication does with the development of mobile communication, in which conformal antenna can be used as station antenna and portable antenna. So the research and analysis on conformal antenna is valuable in the fields of engineering and national defense. The research on conformal antenna"s performance is a very active research field, and it is the important technique in the future intelligent stealth technique and weapon system. In the essence of conformal antenna, there is a kind of antenna which must consider the effect from ambience. When the modeling of antenna is closed to the natural ambience, then we can dope out the antenna performance exactly. However, there are some disadvantages in the study and application of conformal antenna technique at present: most of the studies on conformal antenna have been made in ideal condition, but few in actual working conditions; the analysis method converges slowly and the research hardly meets the requirements of the next analysis. Therefore, theoretical modeling、efficient and accurate analysis methods are done in this paper about dipole antennas conformal to electrically large cylinder. Main contents and innovation points in this paper are as follows: Firstly, the research on finite planar dipole array is presented, which discussed a hybrid method that contained RWG function and equivalent dipole moment model. In the dipole moment model the surface current distribution for each RWG edge element is replaced by the current of an infinitesimal dipole, having an equivalent dipole moment and strength. So the total radiated field is then obtained as a sum of all these contribution of infinitesimal dipoles. This method reduces computation time, and enhances the computation efficiency. Secondly, for solving convergence problem and computation precision problem, an improved integral path"s Watson transformation is put forward, which based on cylindrical carrier model, to predigest the radiated field integral expression. The method based on cylindrical carrier model to use Watson transformation rebuild the path of integration along a steepest descent path on which the integrand decays most rapidly. The simulation results are presented, which indicate the representations obtained here are efficient and valid in the premise of accurate value. Because it deals with complex configuration efficiently, it has larger applicability. Thirdly, for the research on conformal antenna according to its existent theories where mutual coupling effects and mutual coupling compensating are ignored, new methods to compute mutual impedance and compensate for mutual impedance are put forward. In the computing mutual impedance: the new method applying the dipole moment character to amend the mutual coupling from the different integral region, which the hybrid method ignored. In the compensating for mutual coupling, applying receive voltage to compensate the expected voltage method is proposed, thereby the compensating impedance is obtained. Therefore, in the discussion of mutual coupling, the paper adopts double protection, which ensure the little coupling reckon in the mutual computation. The simulation results are presented, which indicate the representations obtained here made a great reduce of sidelobe of radiated pattern and RCS efficiently. Finally, for the model precision and RCS reduction to realize stealth of conformal antenna"s scattering performance, new methods to compute RCS and realize RCS reduction are put forward. In the computing of RCS: it is proposed in the paper that NURBS+MOM hybrid technology should be applied to model electrically large cylinder, and the method reduced the error which comes in the planet element approximate to cylindrical carrier greatly. The method optimized computation efficiency and accuracy, which analyses scattering character reckoning in the carrier effect, and this made the method have practical meaning. In the RCS reduction: induction loop is used to control impedance value and the resonant point. The simulation results proved that the method reduced the RCS greatly in the premise of little effect on gain. Inclusion, the research on performance of dipole antennas conformal to electrically large cylinder had been simulated in this paper, and new algorithms and scheme to resolve the radiated performance、mutual coupling estimate and compensating for mutual coupling、the RCS estimate and RCS reduction have been proposed, the experimental results indicated that the algorithms and scheme can get better results.
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