用特征散射方向图预估电大平面阵的散射

利用平面照射波在无限大周期阵列上感应电流的周期特性，对无限阵列格林函数加窗的方法得到了有限阵列的格林函数，从而将电大有限阵列的分析缩减到单个的阵元上。进而由矩量法得到单个阵元上的电流分布和散射场，并定义为单元的特征散射方向图。仿照阵列综合理论，整个阵列的散射归结为特征散射方向图和阵因子的乘积，极大的简化了电大有限阵列的散射分析，并通过算例验证了该方法的有效性。     

大型阵列结构电磁散射的P-FFT算法

提出利用预校正的快速傅立叶变换(P-FFT)和矩量法(MoM)快速分析电大阵列结构的电磁散射特性.研究了适合于电大尺寸结构近区和远区场计算的格林函数的快速算法,同时,利用Rao-Wilton-Glisson(RWG)函数作为基函数和测试函数,可以考虑阵列单元任意方向的表面电流或磁流分布,并利用P-FFT加速矩量法的矩阵求解,减少内存需求和计算时间.计算结果表明该方法特别适合于大型阵列电磁散射特性的分析.     

基于Bessel权向量的宽带波束形成器

针对均匀线阵接收宽带信号产生的方向图畸变问题, 提出了一种基于Bessel权向量的宽带波束形成器.从截断后的Bessel级数展开式与均匀线阵的方向图函数相似的特性出发, 推导Bessel级数的截断位置与阵列单元数的关系, 并确定使用第一类Bessel函数设计均匀线阵的权向量.仿真结果表明:应用Bessel权向量后, 在1~3 GHz频率范围内, 均匀线阵可以无失真地接收宽带信号, 不同频率的方向图函数幅值与期望方向图函数幅值的相对误差降低到10-3以下, 且单元越多相对误差越小.与现有方法相比, 本方法直接利用截断后的Bessel级数展开式系数设计权向量, 计算简单且精度高.     

平面波导缝隙阵列的散射特性分析与计算

应用矩量法和混合位积分方程(MPIE)计算了平面波导缝隙阵列的电磁散射.以屋顶函数(roof-top)作为基函数和检验函数,计算了x方向和z方向的磁流分量,进而求解了整个阵列的散射.为了减小求解矩阵方程时的计算量和存储量,采用了加速方法对整个计算进行加速,并将所得的数值结果与实验值进行了比较,验证了方法的准确性和有效性.     

大型平面阵列天线散射场的快速计算方法

基于子阵思想,提出利用小型平面阵列中的各天线单元的散射场,来等效大型平面阵列中相似阵列环境下的各单元的散射场,进而利用叠加定理来计算大型阵列的总散射场.并通过公式推导,进一步简化了该方法的操作过程,将大型平面阵列的散射计算问题转化为四个小型平面阵列的散射总场计算问题,显著减小了计算量,同时避免了逐个计算单元场而带来的操作复杂度.计算结果与HFSS仿真结果基本一致,验证了方法的正确性.     

平面近场测量中一种口径场重构技术研究

研究了一种用于平面相控阵天线幅相校准和诊断测试的口径场重构技术.该技术基于等效磁流法,引入矩量法建立平面近场数据与阵列天线口径场分布的联系方程,求解此方程获得阵列天线的口径场分布.模拟计算结果与传统的模式展开法对比,证明了等效磁流法的正确性和可行性;接着讨论了平面近场测试中各关键参数对重构结果的影响;最后基于等效磁流法口径场重构技术实现了某有源相控阵天线的测试和校准,证明了该方法的有效性和实用性.     

基于最大功率传输效率法的近场三维方向图赋形

讨论如何利用带约束的最大功率传输效率(CMMPTE)法通过阵列天线来综合三维方向图.通过引入测试接收阵列天线,待设计的阵列天线与之构成无线功率传输(WPT)系统,从而将方向图的综合问题转换成WPT系统功率传输效率(PTE)的优化问题.通过调整约束条件,在保证PTE最大化的条件下可获得阵列天线的激励分布,根据激励分布设计...     

方向图重建方法及其在自适应阵列互耦校准中的应用北大核心CSCD

介绍了方向图重建方法,并将该方法应用在自适应阵列的互耦校准中。该方法基于天线方向图与阵列接收信号间的关系,通过对阵列单元方向图的变换得到阵列互耦校准矩阵。方向图重建方法对于阵列单元结构具有广泛的适应性,不仅可用于线天线阵列,也可用于由微带天线这类平面单元构成的阵列中。论文推导了互耦校准矩阵的公式,并采用一个对称振子阵列、一个微带阵列和一个柱面共形阵列验证了本方法的有效性。     

基于不同等效面的漏波天线辐射特性研究

基于等效原理计算了一款分别使用线电流源与线磁流源激励的一维无限长漏波天线的总场辐射方向图和漏波辐射方向图.应用等效原理,两种辐射方向图均分别使用了等效面电流和等效面磁流两种不同的等效方法推导.使用谱域法推导出天线总场与漏波辐射场方向图的解析解并使用互易性原理推导出总场的辐射方向图以作对比.对比结果显示不同等效面得出的漏波场辐射方向图不同.     

EBG对圆波导介质棒相控阵扫描特性的改善

将电磁带隙(EBG)结构应用到圆波导介质棒相控阵列中,利用EBG结构所具有的表面波带隙特性有效消除了相控阵中的扫描盲区.比较了无限阵列的扫描特性和有限阵列中心单元方向图在EBG加载前后的变化.仿真分析表明,以EBG结构作为圆波导介质棒相控阵的地平面,能有效消除扫描盲区,扩展扫描范围.     

波导端头裂缝有限相控阵单元的阵中特性

本文利用矩量法对以矩形波导端头裂缝为辐射单元的有限相控阵的单元阵中方向图及口面磁流分布进行了计算,讨论了不同位置辐射单元在不同扫描角时互耦对口面分布的影响。     

A theoretical and experimental study of mutual coupling inmicrostrip antenna arrays

Each microstrip antenna element in the array is replaced by an equivalent magnetic current source distribution over a grounded dielectric slab derived from the electric field on the walls of the element as given by the cavity model. A dyadic Green's function is developed for a grounded dielectric slab, using the rectangular vector wave functions. The function is used to calculate the magnetic field due to the magnetic current distributions. The formula for mutual impedance based on the reaction concept is used to calculate the mutual coupling in arrays of antenna elements. Some measurements have been conducted for mutual coupling between two rectangular patches in the C-band. Calculated results are in excellent agreement with measurements, including those of other authors     

Fractal design of multiband and low side-lobe arrays

Most array factor design techniques are highly dependent on the operating wavelength. In this paper, a novel technique based on fractal structures is described for multiband operation. The analysis is focused in two different approaches: the fractal spatial arrangement of array elements and the fractal design of array factors. Although the patterns of fractal arrays show some interesting similarity properties at several bands, the directivity is not held constant through the bands. Nevertheless, such structures have been shown to be useful for designing low side-lobe arrays with equally weighted current elements. On the other hand, the fractal array factors presented do keep the same shape at several bands because they are designed as self-similar curves. The arrays that would synthesize such patterns present a characteristic power-law current distribution analogous to the spectral distribution of the bandlimited fractal Weierstrass function     

矩形波导纵缝阵列的理论计算

利用矩量法对矩形波导宽边纵缝阵列进行了理论计算。首先利用等效原理及切向磁场的连续性给出了求解阵列纵缝口面磁流的积分方程．后对一实际阵列进行了计算．计算结果与测试结果吻合良好。     

A current mirror based on single electron devices

We have fabricated Coulomb blockade devices which act as current mirrors. Each sample consists of two nominally identical one-dimensional arrays of small tunnel junctions. Each electrode of one array is capacitively coupled to two electrodes in the other array. By measuring the current voltage characteristics of the two arrays simultaneously, we observe a coupling between the currents in the two arrays. We have studied the properties both in the superconducting state and in the normal state, and we interpret the data in terms of correlated transport of charges in the two arrays. The locking between the currents in the two arrays is strongest for intermediate magnetic fields where the electrodes are still superconducting. At best we find current locking over a range of ±6.7 pA     

模拟退火法在阵列天线综合中的应用

介绍了模拟退火法的基本原理。该方法具有全局寻优能力,在阵列天线综合中主要有以下3方面的应用:对均匀阵列的电流分布,对非均匀阵列的阵元位置及电流分布进行优化,对阵列进行稀疏化。仿真结果表明,模拟退火法是一种有效的阵列天线优化综合方法。     

Properties of a cylindrical antenna in an infinite planar or collinear array

A solution is given for the active impedance and current distribution on a cylindrical antenna in a uniform, infinite, planar, or collinear array. The analysis is applicable to the case in which the distance in the collinear direction between the ends of adjacent elements is small. The current distribution on the collinear array is found by relating the antenna current and electric-field variation on the cylindrical surface of infinite length which contains the array. This analysis is then extended to consider a planar array. Results obtained are applicable to any combination of element length and array phasing, for arrays with or without a ground plane. Comparisons with other investigations based upon sinusoidally distributed currents reveal substantial discrepancies for some configurations.     

曲面阵列结构散射与辐射特性的迭代分析

建立了一种适用于曲面有限阵列结构辐射与散射特性分析的迭代方法。首先根据阵列结构相同单元电流分布的相似性,对曲面有限阵列单元几何形状和表面电流分布作了两个假定,将有阵阵格林函数法推广应用于曲面有限阵列结构的分析;然后给出曲面有限阵列结构迭代分析的一般公式,通过迭代运算来消除两个假定近似的影响;最后迭代运算来消除两个假定近似的影响;最后以有两曲面带栅的散射和线源激励曲面带栅结构的辐射分析为例,验证了方法的有效性,并同逐元法作了比较,给出了有关的数值计算结果。结果表明：这种迭代法不受阵面曲率变化、单元数量和分布情况的限制,对有限周期和非周期阵列的分析都有着较高的计算效率和稳定性。     

Rate equations analysis of phase-locked semiconductor laser arrays under steady state conditions

Rate equations analysis of phase-locked semiconductor laser arrays has been carried out. It was found that for given (Laser) current densities, the photon density distribution in the array elements is that particular one which maximizes the total photon density. The results of this analysis were then combined with the waveguiding properties of the laser array waveguide, yielding a basic model of phase-locked diode laser arrays. This model explains the effects of the variation of the current combination through the array elements on its mode structure that were observed recently.     

一种计算电磁棍合微带振子上电流分布的新方法

微带天线振子上电流分布以及微带天线阵中单元间相互耦合分析是微带天线及其阵列分析的关键,由于此分析过程涉及到Sommerfeld积分,使得微带天线上电流分布的求解十分烦琐、费时。为此,本文提出了一种基于Chebyshev多项式展开的方法来计算Sommerfeld积分,进一步求出微带天线上电流分布。结果表明,这种方法在保持较高计算精度的同时大大地提高了计算效率。