Particle-Swarm Optimization in Antenna Design: Optimization of Log-Periodic Dipole Arrays

This paper presents a short tutorial and overview of optimization algorithms based on particle-swarm schemes, and their application to solving electromagnetic problems. As a practical example, a particle-swarm optimization (PSO) tool has been applied in conjunction with the Numerical Electromagnetics Code (NEC) to get the design curves of optimized log-periodic dipole arrays (LPDAs). The graphs show the performance of several radiation parameters (directive gain, front-to-back ratio, bandwidth, SWR, and half-power beamwidth in the E and H planes) as a function of typical design parameters of log-periodic dipole arrays (geometrical parameters and characteristics of the feed). Examples of optimized antennas are given, and their performance is compared to that of standard log-periodic dipole arrays.     

Periodicity Perturbed Grounded Frequency Selective Surface Arrays as Millimeter Wave Random Phase Coherence Destroying Diffusers

This paper presents the design, construction and testing of perturbed periodicity slot type grounded Frequency Selective Surface (FSS) array as millimeter wave (mm-wave) random phase diffusers to eliminate speckle in active mm-wave imaging. To create a random phase diffuser for destroying the coherence of mm-wave sources we proposed FSS based diffusers arrays where the periodicities between the elements are different thought the slot of the cells are similar. The impacts of periodicity variations of both TM and TE field directions have been investigated. The periodicity of an FSS is the main design parameter used to optimize the phase shifting properties of the arrays. The critical parameters of the diffuser arrays design, such as phase relation with periodicity and optimum designed consideration are discussed. We designed the FSS arrays with Finite Integral Technique, fabricated by using etching technique and characterized the S-parameters with a free space Millimeter Wave Vector Network Analyzer (MVNA).     

Simple design rules for single-lobe operation of (evanescentlycoupled) index-guided phase-locked arrays of diode lasers

The author presents both a simple yet very accurate Gaussian beamwaist approximation for the fundamental mode of the symmetric slab waveguide as well as simple design criteria for virtual, sing-lobe operation of phase-locked arrays of diode lasers. Closed-form analytic expressions, involving all parameters characteristic of index-guided, uniform arrays, are determined for the condition that at least 80% of the emitted energy is contained in the main lobe when all emitters are in phase. The effects of the various array parameters on the single-lobe condition are discussed     

一种可折叠的米波超宽带天线阵列设计

扩大槽线单元开口渐张的比例因子并优化其他参数,压缩天线尺寸,采用金属框架结构,结合镂空和局部切割方法,实现米波超宽带天线单元小型化和轻量化设计。双极化单元正交排布,通过单元分步折叠和阵列骨架分块折叠,实现大型阵列天线自动化撤收与架设。实验阵列口径超过18 m×6 m,可在15 min 内实现快速折叠或展开。实验天线的测试结果与设计一致,表明分析与设计方法正确有效,可推广应用于各种宽带天线及大型阵列天线设计。     

一种新型小型化带线印刷对数周期偶极天线

为了实现带线印刷对数周期偶极天线的小型化,本文采用一种矩形电容贴片的单元作为该天线的谐振单元,实现了该天线的小型化。文中对该贴片单元的各种设计参数的设计原则进行了计算和分析,根据分析结果设计了尺寸减缩比为0.7的小型化对数周期偶极天线和普通印刷对数周期偶极天线,进行了驻波比和方向图的测试,测试结果表明这种方法没有带来性能的剧烈恶化,是一种有效的小型化方法。     

Maximizing Transfection Efficiency of Vertically Aligned Silicon Nanowire Arrays

Vertically aligned silicon nanowire (VA‐SiNW) arrays are emerging as a powerful new tool for gene delivery by means of mechanical transfection. In order to utilize this tool efficiently, uncertainties around the required design parameters need to be removed. Here, a combination of nanosphere lithography and templated metal‐assisted wet chemical etching is used to fabricate VA‐SiNW arrays with a range of diameters, heights, and densities. This fabrication strategy allows identification of critical parameters of surface topography and consequently the design of SiNW arrays that deliver plasmid with high transfection efficiency into a diverse range of human cells whilst maintaining high cell viability. These results illuminate the cell‐materials interactions that mediate VA‐SiNW transfection and have the potential to transform gene therapy and underpin future treatment modalities.     

一种小型四阵元GPS天线阵列的设计

分析了GPS微带天线阵列阵元间的互耦特性,得出了满足互耦要求的合适的最小阵元间距;设计了一种小型四阵元GPS微带偏振天线阵列,该阵列采用传统右圆极化阵元舜口双线性极化阵元相结合,使得相同阵元的天线阵列的自由度提高;从仿真的结果可以看出,在不增加阵列面积的情况下,该阵列能够在干扰方向产生比传统微带天线阵列更深的零陷,很大程度地提高了阵列的抗干扰性能;最后给出了GPS微带双频偏振层叠天线的一些重要的设计参数.     

Waveguide electrooptic switch arrays

A review is presented of electrooptic waveguide switch arrays with strong emphasis on those based on titanium-diffused lithium niobate waveguides. Crosspoint and array design considerations and performance are discussed as are waveguide technology limits. Switch array demonstrations are reviewed. Experimental demonstrations of switch arrays are described and particular parameters of the array, including insertion loss, crosstalk, and switching voltage achieved by several laboratories, are discussed and compared. Results of high-speed switch arrays are also described     

The Pareto Optimization of Ultrawideband Polyfractal Arrays

The application of global optimization techniques, such as genetic algorithms, to antenna array layouts can provide versatile design methodologies for highly directive, thinned, frequency agile, and shaped-beam antenna systems. However, these methodologies have their limitations when applied to more demanding design scenarios. Global optimizations are not well equipped to handle the large number of parameters used to describe large- antenna arrays. To overcome this difficulty, a new class of arrays was recently introduced called polyfractal arrays that possess properties well suited for the optimization of large- arrays. Polyfractal arrays are uniformly excited with an underlying self-similar geometrical structure that leads to aperiodic element layouts. This paper expands on polyfractal array design methodologies by applying a robust Pareto optimization technique with the goal of reducing the peak sidelobe levels at several frequencies specified over a wide bandwidth. A recursive beamforming algorithm and an autopolyploidy based mutation native to polyfractal geometries are used to dramatically accelerate the genetic algorithm optimization process. This paper also demonstrates that the properties of polyfractal arrays can be exploited to create designs that possess no grating lobes and relatively low sidelobe levels over ultrawide bandwidths. The best example discussed in this paper maintains a dB peak sidelobe level with no grating lobes from a , to more than a minimum spacing between elements, which corresponds to at least a 40:1 bandwidth for the array.     

Signal Relay Systems Using Large Space Arrays

The results of an investigation of the feasibility of using passive space arrays as highly efficient signal reflectors is reported. The design selected as having the maximum efficiency in terms of the ratio of the signal energy reflected in the required direction to the weight of the space array is a gravity gradient stabilized planar array of dipoles connected and supported by lightweight dielectric filaments. The system and space array parameters required to give a high capacity system output are examined together with the flexibility of the system parameters and operations. This analysis is to determine if a high-capacity space array system can be designed with a potential capability to operate with small stations in both the transmit and receive modes; to achieve significant improvements in spectrum utilization over that achieved in conventional active satellites; and to provide accurate position information. The status of the investigation and the need for additional experimental programs are also discussed. The Appendixes are on signal processing for the space arrays, dipole arrays as reflectors for active satellites or ground antenna systems, and space grating arrays to relay optical signals.     

Design of the microlens arrays coupling with imaging fiber bundle

To ameliorate the disadvantages of imaging system coupled with imaging fiber bundle, a method by adding square aperture microlens arrays at both entrance and exit ends of the imaging fiber bundle is proposed to increase the system’s coupling efficiency. The expressions for solving the parameters of both ends’ microlens units are deducted particularly. The microlens arrays used for an infrared imaging fiber bundle with the single fiber diameter of 100 μm and core diameter of 70 μm are designed by this method. The simulation results show that compared with the system without microlens arrays, the fill factor of the imaging fiber bundle coupled microlens arrays system is increased from 44.4% to more than 90%, and the coupling efficiency is doubled too. So the design method is correct, and the introduction of microlens arrays into imaging fiber bundle coupled system is feasible and superior.     

Statistical signal integrity analysis and diagnosis methodology for high-speed systems

This paper discusses an efficient statistical analysis methodology for system-level signal integrity analysis. In the proposed method, statistical variations of the design and operational parameters are mapped to system performance through simulations based on orthogonal Taguchi arrays. Using the sensitivity functions derived from these simulations, statistical distributions of the performance measures are computed. The sensitivity functions and probability distributions of the design parameters are utilized as a diagnosis tool to estimate the design parameters of a system for a given measured performance. The statistical methodology is applied for design space exploration to improve system performance. For demonstrating the concept, a source synchronous memory bus and a peripheral input-output (I/O) bus have been analyzed under design and operational variations.     

Design of Fiber-Laser Arrays with Genetic Algorithms

The optimization of the far-field pattern of fiber-laser arrays is investigated based on genetic algorithms. A derived objective function of the far-field pattern performs the task of evaluating each of the fiber-laser designs generated by the genetic algorithm. The constrained parameters of the design included are radius of the fiber a, the important V value, the fiber-to-fiber separation S, and the operational wavelength λ. As results, sidelobe level is optimized to be -38.83 dB for a circular arrays with the given constrained parameters.     

高性能LD阵列脉冲电源

本文主要论述了高性能半导体激光二极管阵列脉冲电源的电路设计和工作原理,同时,给出了最简单的电路模式和脉冲电源的性能指标。     

Closed-form mapping conditions for the synthesis of linear processor arrays

This paper addresses the problem of mapping algorithms with constant data dependences to linear processor arrays. The closed-form necessary and sufficient mapping conditions are derived to identify mappings without computational conflicts and data link collisions. These mapping conditions depend on the space-time mapping matrix and the problem size parameters only. Their correctness can be verified in constant time that is independent of problem size. The design of optimal linear processor arrays is formulated as a mathematic programming problem, which can be solved efficiently by a systematic enumeration of a polynomial search space.     

电磁异向介质在阵列天线中的应用研究

为了抑制阵列天线单元的表面波,并减小阵元间的耦合效应,研究了电磁异向介质材料在抑制阵列天线互耦效应中的应用. 基于开口谐振环(Split-Ring Resonator,SRR)负媒质材料特性,将SRR结构单元加载于阵列天线之中,提出了具有互耦抑制效应的天线设计方法. 仿真结果表明：加载SRR结构单元后,天线谐振工作频点处的耦合系数降低了8.8 dB,即由原来的-16.3 dB降低到了-25.1 dB,而对天线阵列的增益和方向图没有太大的影响,可以满足工程的基本要求. 为设计低耦合的微带阵列天线提供了理论支持.     

一种波导裂缝阵列天线设计方法

结合等效电路法和有源导纳法,将设计波导裂缝阵列天线的Elliott方程改写为两个方程组进行求解,利用归一化电导迭代求解两个方程组,得到裂缝参数,避免了直接求解二元非线性方程而产生的大量无用解。互耦系数gmm的计算采用Taylor级数展开式近似。用等效电路法与本文方法分别设计了64元驻波线阵,仿真结果表明,本文方法降到了天线副瓣。     

Analytic design of conformal slot arrays

A completely analytic design process has been developed for small slot arrays which accounts for the varying effect of mutual coupling as a function of element position. A previously developed theory for the design of small arrays has been extended to include conformal dielectric-filled waveguide slot arrays. Computer software has been assembled which enables calculation of the slot geometries required to implement a specified aperture distribution and input impedance condition. The slot self- and mutual admittances are calculated numerically, thus eliminating the traditional measured slot data from the design process. This design technique has been applied to conformalX-band slot arrays on cylinders of a few wavelengths diameter. The arrays consist of multiple dielectric-filled waveguides, each of which is a narrow-band standing-wave linear array of longitudinal shunt slots. The computerized design process adjusts the length and offset of each slot in the total array until the desired aperture distribution and impedance match are achieved. A flow diagram of the design program and test results from experimental arrays are presented.     

Control generation in the design of processor arrays

The problem of mapping algorithms onto regular arrays has received great attention in the past. Results are available on the mapping of regular algorithms onto systolic or wavefront arrays. On the other hand, many algorithms that can be implemented on parallel architectures are not completely regular but are composed of a set of regular subalgorithms. Recently, a class of configurable processor arrays has been proposed that allows the efficient implementation of piecewise regular algorithms. In contrary to pure systolic of wavefront arrays they are distinguished by a dynamic configuration structure. The known trajectories, however, cannot be applied to the design of configurable processor arrays because the functions of the procesing elements and the interconnection structure are time- and space-dependent. In this paper, a systematic procedure is introduced that allows the efficient design of configurable processor arrays including the specification of the processing elements and the generation of control signals. Control signals are propagated through the processor array. The proposed design trajectory can be used for the design of regular arrays or configurable arrays.     

斜射波束梳形微带行波阵的设计

本文讨论了一种关于微带天线阵的设计技术,这种技术可用于设计任意波束指向的梳形微带行波阵。由于采用了行波结构和特殊设计,所以能够获得较宽的频带和较低的副瓣电子。文中给出了两个斜射波束梳形微带行波阵的设计实例,实验表明这种天线具有良好的电特性。