螺旋倒相型天线的分析

本文应用反应积分方程，考虑任意倾斜导线间的互阻抗，建立起广义阻抗矩阵，采用矩量法求出该天线的电流分布，进而获得辐射特性及输入阻抗等。计算结果与实测值吻合较好，计算精度令人满意，本文的分析结果对螺旋倒相型天线的设计、改进、提高是很有用的。     

嵌入匹配网络的电小天线的优化设计

本文提出一种把电感级联网络嵌入多偶极子电小天线中,用来展宽偶极子电小天线的阻抗特性的天线模型和网络参数综合的方法.由于在电小天线阻抗计算中,存在着较大的误差,影响匹配网络参数设计准确度,本文依据多端口阻抗测试的结果,采用随机优化方法,综合出电感级联网络的参数,最终参数综合计算的结果与实验的结果相当吻合,验证了这种方法的有效性.     

离子回旋共振加热天线阻抗模拟计算

利用三维天线平板模型对托卡马克离子回旋共振加热天线阻抗进行模拟计算,并以托卡马克离子回旋共振加热简单环天线为例,计算得到不同条件下的天线阻抗。计算结果表明,天线结构尺寸、等离子体密度分布以及天线与等离子体间的距离参数对天线阻抗都有不同影响。结果有助于离子回旋共振加热天线的设计和阻抗匹配。     

一种基于FDTD的简单有效的天线阻抗计算方法

本文从有源区的软激励时Yee差分方程出发,推导了一种适用于理想的间隙激励(δ-gap source)和探针激励的天线输入阻抗新的计算公式,该方法简洁、有效,公式物理意义明确,能够有效地消除硬激励(hard source).计算天线阻抗时,在频率很低接近零时阻抗值的严重失真,使得应用时域有限差分法计算天线输入阻抗变得更加快捷适用.最后,本文应用该方法分别计算了一个单极子天线和同轴馈电的微带天线,单极子天线的计算结果和前人的计算结果吻合得很好,并且消除了频率接近零时以前计算结果的严重失真,微带天线和已有软件的计算结果进行了比较,得到了满意的结果.     

双环天线的阻抗计算和匹配

本文介绍了、有关计算平行双环互阻抗的文献,提供了双环天线的阻抗计算公式和有关数表,讨论了终端加载以及附加调配线的实用双环天线的阻抗计算方法。     

阻抗加载对微带天线辐射和散射的影响

计算了阻抗加载对微带天线RCS的影响，以及加载不同阻抗时天线的辐射性能。结果表明，阻抗加载主要降低天线带内RCS。适当的阻抗加载能有效降低天线RCS，同时还能保证天线的辐射性能。     

有源天线的原理与应用

本文叙述了单个有源发射天线、单个有源接收天线、有源发射天线阵及有源接收天线阵的工作原理和基本特性。详细讨论了计算有源发射天线阵和有源接收天线阵的自阻抗与互阻抗的公式。并给出了一些实验结果。     

基于多项式的弯折偶极子射频识别标签天线阻抗预测研究

在解决射频识别(RFID)标签天线设计中阻抗计算速度慢的问题的过程中,针对其中较为复杂的阻抗耦合情况,该文提出一种基于多项式的弯折偶极子RFID标签天线阻抗预测方法。首先使用基于天线尺寸的阻抗变换与线性化假设建立模型假设;然后在具体的天线结构中收集数据并进行相关性分析与回归拟合验证假设正确性;最后实验验证使用该方法进行的阻抗预测相对于计算机仿真的准确性、高效性与普适性。试验结果表明,使用该方法替代计算机进行弯折偶极子RFID标签天线阻抗计算时,其预测阻抗相对于计算机仿真结果在保持较高预测准确率的同时极大地缩短了阻抗计算时间,同时该方法在中国应用频段上针对不同弯折次数的弯折偶极子RFID标签天线仍然适用。     

基于多项式的弯折偶极子射频识别标签天线阻抗预测研究

在解决射频识别(RFID)标签天线设计中阻抗计算速度慢的问题的过程中,针对其中较为复杂的阻抗耦合情况,该文提出一种基于多项式的弯折偶极子RFID标签天线阻抗预测方法.首先使用基于天线尺寸的阻抗变换与线性化假设建立模型假设;然后在具体的天线结构中收集数据并进行相关性分析与回归拟合验证假设正确性;最后实验验证使用该方法进行的阻抗预测相对于计算机仿真的准确性、高效性与普适性.试验结果表明,使用该方法替代计算机进行弯折偶极子RFID标签天线阻抗计算时,其预测阻抗相对于计算机仿真结果在保持较高预测准确率的同时极大地缩短了阻抗计算时间,同时该方法在中国应用频段上针对不同弯折次数的弯折偶极子RFID标签天线仍然适用.     

V型天线的行波加载公式

本文研究了ｖ型天线上电流分布与阻抗加载的关系，导出了支持天线上行波电流的阻抗加载公式。讨论了天线张角、振子半径以及振子长度与加载量的关系和规律，说明了加载Ｖ型天线的宽带特性。文中还计算了在高斯脉冲激励下，不同加载量的天线上瞬态电流的分布，由此可以表明所导加载公式的正确性与重要性。     

A numerical technique for calculating mutual impedance and element patterns of antenna arrays based on the characteristics of an isolated element

A numerical technique for calculating mutual impedance and element patterns of antenna arrays based on the characteristics of an isolated element is presented. The basis for this technique is the theory of minimum-scattering (MS) antennas and, in particular, the interpretation of the mutual impedance between two canonical minimum-scattering (CMS) antennas as the first term in a perturbation series of the mutual impedance of arbitrary antennas. For the computation of the mutual impedance via the CMS approximation this pattern must be continued analytically into the complex domain. However, numerical codes provide radiation patterns only for real observation angles. To overcome this problem, the numerically calculated patterns are expanded in terms of spherical modes and the computation over complex angles is carried out analytically. Numerical results for collinear and linear arrays of parallel electric dipole antennas and rectangular probe-fed patch antennas are presented and a comparison is made with direct calculations using the WIPL-D code. Results presented show the good agreement between the CMS approximation and the WIPL-D code.     

Theoretical Investigation of the Input Impedance of Gap-Coupled Circular Microstrip Patch Antennas

In this paper, we have explored a simple theoretical input impedance computation technique for the two gap-coupled circular microstrip patch antennas by using circuit theory approach. The frequency characteristics of the input impedance of the two gap-coupled circular microstrip patch antennas with the gap-distance between the feed patch and parasitic patch is analyzed and simulated. The effect of feed location in the feed patch on the input impedance of proposed antenna is also studied. The theoretical results are compared with the simulated results as well as other reported literature. The simulation has been performed by using a method-of-moment based commercially available simulator IE3D.     

Wide-band EMC analysis of on-platform antennas using impedance-matrix interpolation with the moment method-physical optics method

An efficient method for the broadband EMC analysis of on-platform antennas is proposed, where the hybrid moment method-physical optics (MM-PO) formula is employed to generate the impedance matrix. The impedance matrix is calculated at relatively large frequency intervals and interpolated to approximate its values at intermediate frequencies. Numerical examples, including the coupling and radiation pattern evaluation of on-platform antennas, are presented. Through these examples, it is shown that the proposed method can greatly reduce the computing time in the wide-band computation compared with the traditional MM-PO method.     

Efficient wide-band evaluation of mobile communications antennasusing [Z] or [Y] matrix interpolation with the method of moments

The development of novel antennas for mobile communications often relies on performance simulations. The evaluation of the antenna surface currents for many frequencies using the method of moments (MoM) can take a long time since the impedance matrix must be computed for each new frequency. This paper investigates and compares two efficient methods for the computation of the broad-band performance of mobile communications antennas using frequency interpolation of either the MoM impedance matrix [Z] or admittance matrix [Y]. In either method, the elements of only a few matrices at relatively large frequency intervals are directly computed. These matrices are then used to interpolate the elements of the respective [Z] or [Y] matrices at the intermediate frequencies. Both methods reduce the time it takes to compute the antenna performance over a wide frequency band. The implementation of each method to evaluate the performance of several different antennas used for mobile communications is discussed. Examples with both frequency-domain and time-domain results are presented and both near-field and far-field quantities are considered. The accuracy, the simulation run times, and the computational requirements of direct MoM, [Z] matrix interpolation, and [Y] matrix interpolation are compared     

Efficient analysis of input impedance and mutual coupling of microstrip antennas mounted on large coated cylinders

An efficient and accurate hybrid method, based on the combination of the method of moments (MoM) with a special Green's function in the space domain is presented to analyze antennas and array elements conformal to electrically large material coated circular cylinders. The efficiency and accuracy of the method depend strongly on the computation of the Green's function, which is the kernel of the integral equation that is solved via MoM for the unknown equivalent currents representing only the antenna elements. Three types of space-domain Green's function representations are used, each accurate and computationally efficient in a given region of space. Consequently, a computationally optimized analysis tool for conformal microstrip antennas is obtained. Input impedance of various microstrip antennas and mutual coupling between two identical antennas are calculated and compared with published results to assess the accuracy of this hybrid method.     

Analysis of microstrip antennas using moment methods

The method of moments is used to analyze microstrip antennas of rectangular and nonrectangular shape. Surface currents are used to model the microstrip patch and volume polarization currents for the dielectric slab. The method requires unusually precise computation of the impedance matrix but is capable of accurately predicting currents, impedance, and resonant frequency of the antenna.     

Analysis of microstrip antenna structures using the `add-on'technique

Microstrip antennas and antenna arrays are analyzed using the add-on technique. The goal of this work is to provide a way of handling more than 1000 unknowns while maintaining agreement with the moment method. The problem of a 1008-unknown finite array, with 11 elements and connecting and feeding lines, is an example of the capability of the method. In a CPU time of 1.5 h for each frequency point, accurate impedance results are obtained from the resultant standing-wave pattern along the feeding microstripline. The accuracy of the method is established by comparison with published results when possible, and by the computation of the root mean square (RMS) error in the boundary condition on the conductor     

快速PO-MoM技术分析电大载体线天线宽带特性

PO-MoM混合方法是研究电大尺寸载体上天线特性的有效方法。在应用PO-MoM分析复杂载体上天线宽频带电磁辐射问题时,由于需要在间隔很小的多个频率点进行填充阻抗矩阵的运算,计算过程耗时多,效率低。本文采用阻抗插值技术,通过构造有理插值函数来快速计算PO-MoM中的阻抗矩阵,并在迭代求解方程过程中采用了一种近场预条件技术,节省了计算时间,提高了计算效率。采用上述快速技术计算了垂直安装于平板的单极子天线和星载螺旋天线的宽带特性,并探讨了阻抗矩阵插值技术实现过程中一些参数的选取的问题。数值结果表明,结合阻抗插值矩阵插值技术并使用预条件技术的PO-MoM可以快速有效地分析大型复杂载体上天线的宽频带特性。     

基于MoM-UTD混合方法的阻抗矩阵插值快速扫频技术

MoM-UTD混合方法是一种分析电大平台上天线问题的有效方法.在用该方法分析机载平台上天线间隔离度的频率特性时,由于每一个频点都需要重新计算阻抗矩阵,因此分析整个频带内隔离度的计算量很大,耗时很长.基于此,笔者将阻抗矩阵插值技术引入MoM-UTD混合方法,只直接计算频率间隔较大几个离散频点的阻抗矩阵,频带内其它频点的阻抗矩阵通过对每一个矩阵元素插值得到,从而实现了隔离度的快速扫频,大大减少了计算量,缩短了计算时间.     

PC集群MPI并行矩量法分析复杂平台多天线特性

为分析安装于诸如飞机、舰艇等复杂目标上多天线的电磁兼容性,本文引入了Costa基函数对多天线线面连接结构进行建模.针对计算量过大、耗时太长这一主要障碍,结合RWG基函数特点,设计了一种高效的适用于共轭梯度方法求解的棋盘状并行矩阵填充算法,避免了RWG基相互作用的重复计算,然后详细地讨论了并行共轭梯度算法求解矩量法矩阵方程的并行实现过程.本文进一步开发并在PC集群中实测了MPI并行矩量法程序性能,作为应用计算了安装于某飞机头部的多天线辐射特性.