用MOM-UTD混合方法计算共形天线阵单元间的互耦

采用矩量法(MOM)结合一致性绕射理论(UTD)来计算共形天线阵单元间的互耦。这种混合方法通过UTD来修正MOM中的广义阻抗矩阵将理想导体曲面对天线的影响考虑在内。克服了单独采用这两种方法的缺点。既减少了计算量又达到了一定的精度。计算结果与文献中已有的结果吻合得相当好。     

波导缝隙天线的EBG 的应用

研究一种新型的EBG 结构在波导缝隙天线中的应用。这种新型的EBG 具有可以有效抑制表面波的特性,提出了在阵面缝隙单元间加载EBG 周期单元结构的方案,抑制波导缝隙天线之间的互耦。通过与传统的波导缝隙天线进行比较得出加载新型EBG 结构的波导缝隙天线在互耦上有很大改善。     

HFSS/UTD混合法计算电大尺寸导体上的天线

采用高频方法一致性绕射理论(UTD)与电磁场计算软件HFSS相结合的方法,提高HFSS在计算电大尺寸导体上的天线时的效率和精度。文中以圆形地面上的单极子天线为例,说明了该方法的实用性。     

测绘雷达缝隙天线的设计

引言本文采用考虑了缝隙间外部互耦影响的新方法,研制了用于测绘雷达的缝隙天线。该天线长4米,工作在X波段。这种方法能从确定的天线照射求得精确的缝隙尺寸。结果比要求的性能更优。本文还概述了天线结构的设计原则,在最后一节中给出了试验结果。     

遗传算法在非对称单脊波导缝隙天线设计中的应用

将遗传算法成功地应用到非对称单脊波导缝隙天线的优化中,详细讨论了脊形波导缝隙天线进行优化的适应度函数的设计。整个优化过程分为两步进行:首先对天线阵元激励幅值进行初步优化,随后进行波导缝隙偏置以及脊波导双边槽深的优化,并且动态处理阵元间的互耦,最后结合Elliott设计思想采用遗传算法得出了4 cm(1×10)缝阵结果,从而验证了GA算法的有效性与准确性。     

多层介质多导体系统的时域分析

本文给出了谱域法和频域波形迭代法相结合的分析多层介质多导体系统的时域响应算法，考虑了多导体系统中的色散、互耦效应。文章给出的计算结果验证了该方法的可靠性和适用范围。     

背腔式缝隙天线混合方法降耦研究

运用混合降耦方法,提出了一种简单但高效率的减小背腔式缝隙天线耦合的结构,通过放置两对称寄生单元和去介质的降耦方法,经点频优化,与无附加结构的天线相比,在反射系数小于-10dB 的1. 7% 带宽范围内(中心频率为12GHz)互耦降低了9. 7dB,天线的方向图得到了改善,端射方向的能量减小。在点频优化的基础上,通过带宽内的优化进一步改善了耦合性能,在反射系数小于-10dB 的2. 2%带宽范围内互耦降低了11. 5dB。该降耦方法结构简单、成本低、易加工。     

最大似然法测向中的互耦补偿

本文分析了自适应圆阵中阵元间互耦导致最大似然法测向性能下降的机制，提出了一种互耦补偿方法，该方法简便易行，补偿效果良好。     

新型快速波导缝隙天线设计方法

对馈电网络和天线的散射矩阵进行级联,推导了互耦条件下阵列天线输入端口散射参数和天线实际激励分布的计算方法。基于该方法,提出了一种新型快速波导缝隙天线设计方法,并设计了一副12 元宽边纵缝一维波导缝隙天线。测试结果表明,在9. 82 ~10. 21 GHz 内反射系数和副瓣电平分别优于-15 dB 和-28 dB。测试结果与计算、仿真结果吻合良好,验证了该方法的准确性和有效性。     

超低副瓣偶极子相控阵互耦的研究＊

本文首次提出了从网络定义出发求偶极子阵列天线单元间互阻抗的方法,然后提出了用互阻抗矩阵来补偿单元间互耦的方法。计算结果表明:在扫描角不太大的情形下,用本文提出的互耦补偿方法是有效的。并在此基础上讨论了互耦对单元上电流分布规律的影响以及对副瓣电平的影响,为实现超低副瓣相控阵提供了详细的分析依据。     

A UTD based asymptotic solution for the surface magnetic field on a source excited circular cylinder with an impedance boundary condition

An asymptotic solution based on the uniform geometrical theory of diffraction (UTD) is proposed for the canonical problem of surface field excitation on a circular cylinder with an impedance boundary condition (IBC). The radius of the cylinder and the length of the geodesic path between source and field points, both of which are located on the surface of the cylinder, are assumed to be large compared to a wavelength. Unlike the UTD based solution pertaining to a perfect electrically conducting (PEC) circular cylinder, some higher order terms and derivatives of Fock type integrals are found to be significantly important and included in the proposed solution. The solution is of practical interest in the prediction of electromagnetic compatibility (EMC) and electromagnetic interference (EMI) between conformal slot antennas on a PEC cylindrical structure with a thin material coating on which boundary conditions can be approximated by an IBC. The cylindrical structure could locally model a portion of the fuselage of an aircraft or a spacecraft, or a missile. Validity and accuracy of the numerical results obtained by this solution are demonstrated in comparison with those of an exact eigenfunction solution.     

源在曲面上的NURBS-UTD方法的爬行波射线寻迹算法研究

辐射源位于凸曲面上的一致性几何绕射理论(UTD)在分析设计电大尺寸平台上天线的应用广泛,本文给出了一种源点位于任意光滑凸曲面上的UTD爬行波射线寻迹算法,使用数值的微分几何方法对暗区爬行波射线进行寻迹.对目标模型引入非均匀有理B样条(NURBS)曲面进行建模,这使得UTD方法可以应用于以往板、柱、锥模型以外的任意光滑曲面模型.本文算法可应用于任意曲面上,数值结果表明了本文算法的有效性及工程适用性.     

用MoM-UTD混合方法分析机载平台天线间的隔离度

天线间的隔离度是机载平台电磁兼容(EMC)的重要指标之一。由于机载平台的电尺寸很大,因此单纯矩量法(MoM)很难解决。一致性几何绕射理论(UTD)虽是高频方法,适合解决电大问题,但其精度较低。该文采用MoM-UTD混合方法分析机载平台天线间的隔离度,兼顾了计算精度和速度,得到的计算结果和测量值吻合良好。     

Coupling between mutually orthogonal slot antennas covered by an overdense plasma sheath

Measurements of the isolation between mutually orthogonal slot antennas on the surface of a metal cone covered by an overdense plasma sheath are presented. The measurements show that the isolation is essentially the same for small and large input powers and independent of the antenna used as the transmitter. The results also show that the coupling between antennas is greater in the presence of the plasma sheath.     

基于UTD和GA混合算法的无人机载天线布局优化

为克服无人机天线之间的相互干扰,采用遗传算法对天线进行优化布局,以减少天线间的耦合。通过采用一种新的目标函数,结合一致性几何绕射理论对圆柱体上的单极子天线和无人机表面上单极子天线的布局进行优化,得到了最佳的优化位置。通过Feko仿真对优化位置结果进行验证,得到了最佳位置处S参数值,可知天线优化位置后相互之间的耦合度变小,这也间接证明了该方法计算的正确性。该方法能够及时准确地对机载天线间的耦合度进行预测和评估,具有实际应用价值。     

Modeling conformal antennas on metallic prolate spheroid surfaces using a hybrid finite element method

In this paper, the hybrid finite element-boundary integral (FE-BI) method appropriate for modeling conformal antennas on doubly curved surfaces is developed. The FE-BI method is extended to model doubly curved, convex surfaces by means of a specially formulated asymptotic dyadic Green's function. The FE-BI method will then be used to examine the effect of curvature variation on the resonant input impedance of a cavity-backed, conformal slot antenna and a conformal patch antenna recessed in a perfectly conducting, electrically large prolate spheroid surface. The prolate spheroid shape provides a canonical representation of a doubly curved mounting surface. The numerical results for conformal slot and patch antennas on the prolate spheroid are compared as a function of curvature and orientation.     

On the accuracy of the UTD for the scattering by a cylinder

The UTD formulation for the scattering by a cylinder is valid for antennas that are removed from the cylinder surface. The usual guideline is that reliable results can be obtained for antennas that are about λ/4 or more away from the surface. By exploring a few cases, we show that λ/4 is unnecessarily large for the lit region and sometimes too small for the shadow region. In addition, we find that with a simple heuristic modification to the UTD, heights as small as λ/20 can be accommodated, with an accuracy that is sufficient for most engineering applications     

椭球面上缝隙天线间互导纳

本文以微分几何为基础，运用短程线常数和ＵＴＤ公式，首次分析计算了一般椭球面上矩形缝隙天线间互导纳，并给出数值结果。     

Mutual coupling between reduced surface-wave microstrip antennas

An investigation of the mutual coupling between reduced surface-wave microstrip antennas is presented and compared with that for conventional microstrip antennas. Numerical results are presented from a theoretical analysis of the mutual coupling along with confirming experimental results. It is shown that for electrically thin substrates, the space-wave coupling, not the surface-wave coupling, is predominant for typical element spacing, for both the conventional and reduced surface-wave antennas. In addition, the mutual coupling behavior is examined using an asymptotic analysis, which demonstrates how the coupling falls off much faster with patch separation for reduced surface wave antennas compared to conventional microstrip patch antennas     

Hybrid2: combining the three-dimensional hybrid finiteelement-boundary integral technique for planar multilayered media withthe uniform geometrical theory of diffraction

The fully three-dimensional (3-D) hybrid finite element (FE)-boundary integral (BI) technique is extended by further hybridization with the uniform geometrical theory of diffraction (UTD) resulting in a so-called hybrid² FE-BI-UTD approach. The formulation is capable of modeling arbitrarily shaped strongly inhomogeneous objects together with electrically large obstacles of relatively simple shape within the common environment of a planar-multilayered medium. The arbitrarily shaped inhomogeneous objects are discretized by finite elements, whereas, the electrically-large obstacles are described by the UTD and both of these models are included into an integral equation derived from the equivalence principle for planar-multilayered media. Thus, full-electromagnetic coupling is realized between all parts of the formulation. The integral equation is implemented using mixed potentials with appropriate Green's functions derived from Sommerfeld integral representations for planar-multilayered media. The UTD contributions are accounted for by corresponding modifications of the Green's functions and the FE technique is coupled to the integral equation via introduction of equivalent surface current densities in the bounding surfaces of the discretized objects. After presenting the formulation of this novel fully 3-D hybrid² technique, the implemented computer code is validated against conventional hybrid FE-BI computations and a wireless base station antenna is analyzed in several situations of complex real world, microcell environments