一种宽带圆形阵列天线的矩量法分析

利用矩量法对宽带圆形阵列天线的互耦特性进行分析。为了对较粗线天线进行精确分析,矩量法采用正弦差值基函数与点配法,并采用全域线天线积分核计算Pocklington方程,得到天线的广义散射矩阵,实现互耦分析。为了验证其计算结果,对所设计阵列天线进行了CST软件仿真和实验测试。仿真和测试结果表明：矩量法计算与CST仿真结果基本相同,实验测试结果在主波束方向、主波瓣宽度、副瓣电平等特性上与计算和仿真结果近似一致,说明此方法能够有效的对宽带阵列天线进行互耦分析。     

圆形波导中线天线的辐射和互阻抗＊

本文采用并矢格林函数,场量变换和反应原理讨论了圆形波导中线天线的辐射和互耦合,给出了场强和互阻抗的普遍公式。波导是半无限长的,端面反射系数为Γ.天线的长度、馈电点和它们在波导中的位置都是任意的。作为例子,我们给出了四种特殊情况下的互阻抗公式,并进行了讨论。     

矩形波导中线天线的辐射和互阻抗

本文采用并矢格林函数,场量变换和反应概念讨论了矩形波导中线天线的辐射和互耦合,给出了场强和互阻抗的普遍公式。波导是半无限长的,端面反射系数为Γ。天线的长度、馈电点和它们在波导中的位置都是任意的。作为例子,我们给出了八种特殊情况下的互阻抗公式,并进行了讨论。     

天线与天线系统

0210897阻抗加载天线的计算机辅助分析〔刊〕/陈海涛//现代通信技术.—2001,(4).—20～23(C) 本文讨论了用矩量法对线天线的阻抗加载进行计算机辅助分析的问题。详细阐述了阻抗加载天线各种电气指标的计算方法,最后给出了一些计算结果,并与实验测量结果进行了比较,证明本文所介绍的算法是有效可行的。参3     

考虑互耦修正的机会阵雷达波束方向图综合优化

机会阵雷达大量天线单元在空间随机分布,波束方向图综合时考虑阵元间的互耦影响十分必要。该文基于子阵思想,提出交叉划分子阵,利用子阵的互阻抗矩阵构建任意阵的互阻抗矩阵,并结合自适应算法实现了互耦情况下的机会阵雷达的波束综合优化。该方法利用矩量法计算子阵的广义互阻抗矩阵,应用最大输出信噪比准则,在方向图区域施加干扰信号自适应地调整阵因子,综合了非均匀偶极子线阵和面阵,结果与FEKO软件仿真结果吻合良好。     

双位积分方程在分析地面上线天线中的应用

导出了任意取向线天线在基于sommerfeld积分的反射系数近似条件下的双位积分方程,采用多项式基函数和点匹配的矩量法对该方程求解,给出阻抗元素计算的一般表达式.计算结果表明了该方法的有效性.     

耦合腔结构的互作用阻抗的计算

正 1.引言 互作用阻抗是行波管设计中一个十分重要的参量。在耦合腔行波管中,由于电路结构的复杂性,迄今还没有一种分析方法能够精确地计算其互作用阻抗。所以通过冷测来计算互作用阻抗几乎还是唯一实用的方法。虽然利用谐振法测量耦合腔结构的-图和用频率微扰法来测量电场已经是成熟的方法,但是如何从测量的结果来计算互作用阻抗却仍是一个正在探索的问题。本文讨论了从大微扰的测量结果,利用Kosmahl     

分布作用速调管大信号计算模型的研究

该文建立了分布作用速调管(EIK)注波互作用模拟的大信号计算模型。该模型基于1维电子圆盘模型,考虑了电子圆盘间的空间电荷力。在电子与高频场互作用计算中采用双间隙耦合腔等效电路方法,并在间隙阻抗矩阵的计算中考虑了耦合腔中每个间隙电子电导的影响。依据该模型编写了计算程序,并与MAGIC3D仿真结果进行了比较验证,结果相符合。该计算模型可以扩展到三间隙乃至更多间隙谐振腔的分布作用速调管注波互作用的大信号计算模拟中。     

金属介质混合目标散射分析的快速偶极子法

基于等效偶极矩法,该文利用快速偶极子法用于快速计算金属介质混合目标的电磁散射。通过分组技术和简单的泰勒级数展开,将远场组之间的矩阵向量积自然地转化为聚集-转移-发散的形式,实现了矩阵向量积的快速计算。另一方面,由于远场组之间的互阻抗元素不用存储,大大降低了内存消耗。在仿真分析中,为了进一步快速计算近场组中的互阻抗元素,还采用了等效偶极矩法。数值结果表明该方法具有较高的计算效率和令人满意的数值精度。     

线天线的小波矩阵变换法求解

本文研究天线的小波矩阵变换法求解。首先采用三角插值基函数和线天线的一种精确计算模型,利用矩量法得到矩阵方程,然后通过Daubechies离散小波变换进行快速求解。计算结果表明,该方法能够使阻抗矩阵稀疏化,从而提高了求解速度。     

相位加权阵列天线的互耦分析及补偿

采用分段正弦基函数Galerk in法计算了阵列天线的阻抗矩阵,利用互耦阻抗方程分析了相位加权阵列的幅相恶化程度,且用矩量法分析了互耦对两种相对加权阵列天线性能的影响。提出了一种互耦补偿的方法即网络分析法,仿真结果表明了这种补偿方法的正确性和有效性。     

THE LIMITATION OF MUTUAL IMPEDANCE PRECISION TO THE SIDELOBE LEVEL OF ARRAY ANTENNA

Accurate mutual coupling correction is necessary for an array antenna to reach ultra-low sidelobe level.If the mutual impedance or mutual coupling coefficient matrix of an array isperfectly known,theoretically,one can compensate the effects of mutual coupling completelyand realize the desired low sidelobe level.However,the mutual impedance matrix obtainedwhether by calculation or by measurement has limited precision,which limits the effectiveness ofcompensation.This paper deals with the requirements on the precision of mutual impedance forcompensation in ultra-low sidelobe array antennas.The relationship between mutual impedanceerrors and the amplitude and phase errors of an array is derived,by which the relationship betweenthe mutual impedance errors and the sidelobe level is obtained.     

Mutual impedance of hemispherical dielectric resonator antennas

The mutual coupling between two hemispherical dielectric resonator antennas is studied analytically. The radiation fields of the antennas are derived rigorously from a Green's function. The mutual impedance is then determined from a reaction formula. Comparison between theory and experiment is presented     

A broad-banded folded monopole antenna

Electrically short folded monopole antennas with lumped mutual coupling between driven and folded sections are considered, showing that the input radiative impedance exhibits a resonance frequency depending upon the sign and magnitude of the coefficient of coupling. If extended to "n-folded" monopoles with separate lumped mutual couplings, the analysis shows the input radiative impedance will exhibitnstaggered resonance frequencies and bandwidth broadening.     

Theory of mutual coupling among minimum-scattering antennas

A novel and rigorou formulation for mutual impedance among a class of idealized but realizable antennas is presented. Unlike past treatments of mutual coupling, which have proceeded from structurally specified antennas, the present treatment deals with a class of antennas, all the electromagnetic properties of which are rigorously expressed explicitly in terms of their radiation patterns alone. Employing a network formulation based on a scattering representation of electromagnetic fields in terms of spherical (or cylindrical) modes, the mutual impedances between such antennas are computed exactly. Several alternate representations for the mutual impedance are derived, one of which is an integral representation involving the power pattern function for both real and complex angles. In special cases, these exact results agree with published results obtained by applying well-known approximate techniques to structurally specified antennas. An important and illuminating example is provided by an infinite planar array of antennas radiating into a half-space for which the present formulation yields the well-known grating-lobe series representation of the active impedance without an explicit reference to structural properties of the radiating elements.     

Comments on “Anomalous mutual coupling between microstripantennas” [and reply]

The paper by Haddad and Pozar (see ibid., vol.42, no.11, p.1545, 1994) contains important observations about the mutual coupling between printed antennas. It presented the oscillatory behavior of the mutual coupling between two printed dipoles as the separation between elements is increased. The authors used a closed form asymptotic Green's function to evaluate the mutual impedance between the elements. The oscillatory behavior of the mutual coupling is supposed to be a consequence of the interference between the surface waves and the space waves. The authors of the aforementioned paper stated that this behavior was previously unreported. Rosales here comments that the "anomalous" oscillatory behavior of the mutual coupling between microstrip antennas was in fact reported in a paper presented at the Ninth Computing Conference on the Computation of Electromagnetic Fields, and by Haddad and Pozar in their paper, almost simultaneously. The results and conclusions of both papers confirm each other. Haddad and Pozar reply to the Comment     

利用混合模型法计算微带天线间互耦

基于微带天线的传输线模型和空腔模型，提出了一种计算微带天线间互耦的新方法。在本方法中，首先根据腔模法原理，将微带天线等效为相距半波导波长的两个辐射缝隙；然后分别利用微带天线的传输线模型以及微带天线边缘面上的等效磁流分布求出微带天线的自阻抗和互阻抗，并进一步计算微带天线间的耦合系数。最后，利用本文方法编写Matlab程序求解矩形微带天线间的互耦，并与实验进行对比，比较结果验证了方法的高效性和可靠性。     

Theoretical and experimental investigations on microstrip active array antennas and power combiners

In this paper, microstrip active array antennas and power combiners are investigated. The mutual impedance of a rectangular microstrip patch array is analyzed based on the Richmond's reaction integral equation and Galerkin technique in spectral-domain. The computer-aided analysis and design of the active array are then carried out by coupling the mutual impedances to the large-signal characteristics of Gunn diodes with a harmonic balance technique. Based on the theoretical study, microstrip active patch array antennas are investigated experimentally.     

COMPENSATION FOR THE MUTUAL COUPLING EFFECT FOR THE ESPRIT ALGORITHM IN SINGLE SNAPSHOT ARRAY PROCESSING

An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.     

Scattering properties and mutual coupling of antennas with prescribed radiation pattern

An analysis is presented of the interrelations among the radiative, scattering, and coupling properties of arbitrary lossless antennas. The analysis is based on a well-known scattering representation of antennas in terms of spherical modes in free space. This scattering representation is given a network interpretation which brings into focus the degree of interdependence between scattering and radiation characteristics. The scattering matrix of a reciprocal antenna with one port and a prescribed radiation pattern is represented in a canonical form which exhibits explicitly the permissible range of adjustments in the antenna scattering characteristics. The significance of the canonical form is examined from several points of view, noting in particular its connection with the concept of resonant modes of a scatterer. The network interpretation also facilitates the evaluation of mutual coupling, and the mutual impedance between two antennas is expressed explicitly in terms of the radiative and scattering parameters of each antenna. It is shown that, generally, the mutual impedance may be expressed as a sum of two terms: a zeroth-order term, dependent exclusively on the radiation pattern, and a second term involving the scattering properties as well as the radiation patterns. Under certain conditions the mutual impedance may be approximated by the zeroth-order term alone. It is also shown that a similar zeroth-order approximation of the active impedance in an infinite planar phased array leads to a grating lobe series type of representation.