Design of line source antennas for difference patterns with sidelobes of individually arbitrary heights

A design method previously developed to give a sum pattern with arbitrary sidelobe topography is shown to be applicable to difference patterns as well. The basis is Bayliss patterns (Taylor-type patterns for the difference mode) which are transformed through an iterative procedure to the desired result. For practical cases the convergence is rapid and a previously developed do-loop computer program has been modified to facilitate the computations and provide final patterns and aperture distributions.     

基于粒子群算法的阵列天线波束赋形研究

波束赋形可以得到雷达系统所希望的理想辐射波束,然而传统分析方法存在理论分析繁琐、计算量较大的缺点,不利于在实际的工程应用中得到推广和使用。文章提出了一种基于粒子群算法对波束赋形的研究方法,具有代码简单、计算快速准确等优势。根据直线阵列的基本理论建立基本模型及方向图波瓣评估函数,最后得出两个案例的分析结果。计算结果验证了该方法的可行性和高效性,利于在实际工程中得到应用。     

遗传算法在传感器阵列多波束图设计中的应用

由于在水声系统中实际阵列模型往往与理想阵列模型失配,导致基于理想阵列模型设计的波束图在实际应用中严重畸变,从而不能有效地抑制旁瓣干扰,严重影响系统性能.针对常规的波束设计方法应用到实际任意形状阵列时不能有效收敛到期望的最佳波束图,提出了一种基于遗传算法的多传感器阵列波束设计方法,以实现对任意形状阵列的多波束优化设计,获取期望特性的波束图或最佳可得的波束函数.结合运用水池实验测量的16元十字阵的数据,给出了方法基本步骤与多波束设计结果.设计波束满足了应用需要,说明了方法的应用可行性和有效性,且具有很强的宽容性.提出的算法对于实际多传感器系统的多波束设计具有重要意义.     

基于粒子群算法的天线阵方向图优化

雷达阵列天线常涉及方向图综合,而天线阵综合常常是利用优化算法优化单元幅相及间距等参数的过程。粒子群算法具有理论简单、参数少和易于实现等特点,文中基于这一简单易行的优化算法,给出一种阵列天线赋形波束综合方法。通过优化阵列天线中各单元的馈电幅度和相位同时实现主瓣的赋形和副瓣电平的抑制,或通过仅相位加权实现主瓣波束赋形,得到优良的余割平方赋形。通过实例设计验证了粒子群算法优化天线阵方向图的有效性。     

Optimization of Microwave Networks by Razor Search

A new optimization method called razor search is presented. The method, which is based on pattern search, was specifically developed for the automatic optimization by computer of networks for which the objective is to minimize the maximum deviation of some response from a desired ideal response specification. Minimax response objectives, which can lead to equal-ripple optima, will in general give rise to discontinuous partial derivatives of the objective function with respect to the network parameters. Otherwise efficient optimization methods may slow down or even fail to reach an optimum in such circumstances, particularly when the response hypersurface has a narrow curved valley along which the path of discontinuous derivatives lies. Another direct search method called ripple search is also presented. This method was developed to locate the extrema of multimodal functions of one variable in an efficient manner, and is used to determine the maximum deviation of the response from the desired response. Sufficiently detailed flow diagrams are available so that the methods can be readily programmed. The razor search strategy (with ripple search) has been successfully applied to the optimization of inhomogeneous waveguide transformers. It is illustrated in this paper by examples of cascaded commensurate and noncoummensurate transmission lines acting as impedance transformers for which the optima are known.     

Designing the focused and wide beam pattern in linear and planar phased‐MIMO radar considering the antennas' overlap

Phased‐array multiple‐input multiple‐output (MIMO) radar is a new method for collocated MIMO radar, benefiting from its advantages without losing the coherent processing gain considered the main feature of phased‐array radars. In this method, the whole array is divided into several overlapping subarrays; then a waveform is allocated to the antennas of each subarray, which are orthogonal to other subarray's waveforms. In order to obtain a desired beam pattern, appropriate weighting coefficients for each subarray should be designed. This study aimed to design the phased‐MIMO radar's weighting coefficient matrix in two modes: In the first mode, the aim is to design a beam pattern, which has the maximum value in direction of the desired targets. In the second mode, a desired beam pattern is defined, and the coefficients should calculated in such a way that the obtained pattern be as much as possible compatible with the desired patter. In the two modes, the design, at first, is accomplished for linear array and then is extended to the planar array. Moreover, the impact of subarrays' overlap and the power constraints is investigated. The proposed methods, in special cases, are applicable in MIMO and phased‐array radars, too.     

基于有效导热系数法的交界面形状识别算法

基于表面测温的边界形状识别算法研究是红外无损检测技术从定性到定量发展的理论基础,同时也是传热反问题研究的一个重点也是难点问题。对于交界面形状的识别,常规的边界识别算法,由于交界面要在迭代过程中不断变化,所以计算相对复杂,不利于算法的实际应用。在原有边界形状识别研究工作的基础上,通过将交界面形状的识别问题转化为有效导热系数的分布问题,将计算温度和检测温度的吻合程度作为判别条件,利用改进的一维修正算法反演识别有效导热系数的分布,再转化为真实的交界面形状。数值实验表明该方法大大降低了交界面形状识别的复杂性,是解决交界面形状识别问题的行之有效的计算方法。     

基于辅助相位优化的交替投影阵列综合算法

本文提出一种新的方向图快速综合算法.该方法基于交替投影算法（AP）,首先对目标方向图幅度进行限制,其次引入了目标方向图相位变量并对其进行优化,得到最佳目标方向图相位,最后结合临近分裂方法来求解有约束的最小二乘问题（CLMS）以获得满足要求的激励.相比于其他AP类算法只对方向图幅度进行限制的处理,本文对方向图相位的优化处理有助于提高算法的收敛速度和性能.实验结果表明,无论有无激励约束的情况下,该算法均能取得良好的优化效果,且适用于任意阵列,具有很好的推广能力.     

新疆广播电视节目内容监测系统建设的设计

近年来,国家实施了"西新工程",加大了对新疆广播电视事业的建设和投入。建立一个全面、实用、快捷、有效的广播电视节目内容监测系统,必须运用当前先进的数字压缩、网络通讯、视音频比对、智能比对、关键词识别、数据库等技术,采用不同的组网方案,来构建节目内容监测系统的监测方式。通过实时监测、轮询监测、任务监测来达到效果,该系统采用面向服务的架构SOA,基于XML统一标准的系统结构。系统在逻辑上采用基于.Net FrameWork规范的B/S/S(浏览端/服务器/服务器)三层结构模型来设计,形成了整体技术解决方案。     

Radiation pattern of a test reflector antenna from near-fieldmeasurements over focal region of a coupled lens or offsetreflector

A novel scheme has been investigated by which the radiation pattern of a test reflector antenna is determined by rescaling a plot of the electric field distribution in the focal plane of a large lens or in the offset focal plane of a large offset reflector placed in front of the transmitting antenna under test. The major advantage of the technique is that it permits a direct plot of the desired radiation pattern from near-field amplitude data without requiring any phase measurements. The test method is simpler and the test data more accurate than for pervious test methods     

Extension of projection method to nonuniformly linear antenna arrays

The study of linear arrays has been developed in different regions. The computerized techniques that appeared in this century motivated the researchers to find a new techniques that save time. In this work the method of succesive projection is used in solving the nonuniform space and phase arrays. This technique was used before to solve the nonuniform current arrays. The main concept of this method is to find a common point of many different sets. This point will have the best solution to satisfy all conditions. In this technique the solution of the set of inequalities is the main scope. The addition of one or more constraints to the array is only as adding one more set to the group of sets we have. This means that the solution of constrained arrays also is available. Several illustrations are discussed and compared with different other techniques. A simple program is available and easy to establish. In this work, the broadside direction pattern is divided into180degthat represent 180 sets. At each set the synthesized pattern must satisfy the desired pattern.     

分布式阵列方向图综合方法研究

针对分布式阵列孔径栅瓣或旁瓣抑制问题,结合分布式阵列结构与方向图乘积定理, 提出了一种分布式阵列双程方向图设计方法。首先,通过综合适当的阵列因子和子阵方向图函数来最大限度地消除栅瓣并降低旁瓣级;其次,采用 Minimax 准则进行发射方向图权值设计来进一步抑制存在的栅瓣;最终,采用独立的发射和接收天线阵列,基于方向图相乘可以获得无栅瓣影响的大孔径分布式阵列。仿真分析结果表明,该方法能够有效抑制分布式阵列的栅瓣和旁瓣,获得期望的阵列方向图性能,有助于提高雷达探测能力。     

基于约束差分进化的阵列置零

阵列置零的同时,阵列的旁瓣电平升高、主瓣增益降低甚至阵列指向都会发生改变,导致阵列性能降低。针对阵列置零时阵列性能降低问题,提出一种约束优化模型。在约束优化模型中不仅设置了零陷深度约束和近旁瓣电平约束,还设置了阵列期望方向增益约束及阵列指向约束。在满足约束条件下,使得阵列旁瓣电平最低。并且针对标准约束差分进化算法收敛慢,采用自适应约束差分进化(e-SADE)算法,该算法采用多种变异方式相结合、自适应地调节交叉概率和缩放因子。运用自适应约束差分进化分别通过调节阵元相位和阵列功率一定时的阵元权值求解这个约束优化问题,仿真结果表明提出的方法实现了需求的目标方向图,利用自适应约束差分进化算法优化实现阵列置零是有效可行的。     

Design of a Class of Parallel-Coupled Quasi-Stripline Filters by Conformal Mapping (Correspondence)

In some practical cases modified circular-package versions of parallel-coupled stripline fiIters might be more convenient than the conventional flat-package ones. This letter describes a design method for round-package interdigital, comb-line, or similar structures. The method is based on the conformal mapping of a flat filter into the desired configuration.     

傅氏变换迭代法波束赋形的精度和效率

正 (一)傅氏变换迭代法的收敛值和赋形区外的能量 傅氏变换迭代法是新近提出来的波束赋形方法。其赋形精度和效率是天线设计者所关心的问题。本文从迭代法的收敛值和赋形区以外的能量来表示该方法的赋形精度和效率,现讨论如下     

Reducing the Number of Elements in a Linear Antenna Array by the Matrix Pencil Method

The synthesis of a nonuniform antenna array with as few elements as possible has considerable practical applications. This paper introduces a new non-iterative method for linear array synthesis based on the matrix pencil method (MPM). The method can synthesize a nonuniform linear array with a reduced number of elements, and can be also used to reduce the number of elements for linear arrays designed by other synthesis techniques. In the proposed method, the desired radiation pattern is first sampled to form a discrete pattern data set. Then we organize the discrete data set in a form of Hankel matrix and perform the singular value decomposition (SVD) of the matrix. By discarding the non-principal singular values, we obtain an optimal lower-rank approximation of the Hankel matrix. The lower-rank matrix actually corresponds to fewer antenna elements. The matrix pencil method is then utilized to reconstruct the excitation and location distributions from the approximated matrix. Numerical examples show the effectiveness and advantages of the proposed synthesis method.      

Proximity-effect correction for VLSI patterns in electron-beam lithography

A proximity-effect correction method for VLSI patterns has been developed. In this method, a dose ratio has been introduced as a control parameter for the negative- resist thickness after development, in addition to the proximity parameters.A new technique has been used to obtain the proximity parameters. By using the dose ratio and the proximity parameters, both the exposure dose and the size of the irradiated shape are easily determined.A pattern accuracy of ±0.1 μm and a uniform resist of the desired thickness were obtained. The computation time is proportional to 1.2 power of pattern density, and is 100 seconds on a 1.5-MIPS computer when correcting for 10⁴ shapes in a pattern whose pattern density is 10⁴.     

On the design of nonuniformly spaced slot arrays

A technique for the design of nonuniformly spaced waveguide slot arrays is proposed. The slots are in active resonance, and their position is adjusted so that the sources of the array will have the desired amplitudes and phases. The conductances of the slots depend on the desired pattern and the efficiency. Applications on Taylor and cosec ²&thetas; patterns have shown the validity of the method     

A synthesis method for bidimensional apertures

A generalization of the Woodward-Lawson synthesis method is introduced for a wide class of apertures (including as particular cases the rectangular, the rhombic, and the hexagonal). By resorting to a rather general type of bidimensional Fourier series expansion, the aperture distribution is obtained as a superposition of orthogonal constant amplitude linearly phased components, whose complex amplitude coefficients are the values of the radiation pattern in a regular lattice of "cardinal points" on which the desired pattern function is exactly matched As a numerical application of the method, two examples of pattern synthesis with a hexagonal aperture are treated in detail.     

期望主瓣响应下任意阵方向图综合方法

为实现任意阵列天线的方向图综合,特别是考虑到不同空间指向对阵列方向图的影响,提出自适应原理与凸优化理论相结合的方向图综合法.该方法首先利用自适应原理综合法得到所需阵列方向图的旁瓣特性;而后,选择零度角的方向图主瓣作为期望主瓣;最后,在该期望主瓣响应下,将阵列方向图综合问题转化为二阶锥规划问题.采用凸优化循环迭代算法,完成对非凸优化问题的求解,从而保证方向图在满足期望主瓣响应的同时,使旁瓣特性与自适应方向图综合方法得到的结果最接近.理论分析与仿真结果表明,综合后阵列方向图在不同空间指向上具有与期望主瓣一致的主瓣特性,且其旁瓣也能够很好地保持对动态干扰的抑制特性.