基于改进杂草入侵算法的阵元失效校正方法

针对天线损伤造成的阵元缺失问题,出现的旁瓣电平升高、主瓣展宽等性能恶化现象,提出一种通过改变计算适应度方法的改进杂草入侵优化算法.算法能够加快程序运行时间,提高算法效率.并利用改进的杂草入侵优化算法,针对-40dB的32单元阵列为例,随机缺失4阵元后进行优化,恢复原方向图副瓣水平.并且为验证算法在实际工程的应用性,针对16阵元天线采集实测数据进行校正优化.结果显示,上述算法能够有效地解决,阵列天线中天线单元失效后方向图恶化问题.     

遗传算法在阵列天线方向图综合中的应用

应用实数编码的遗传算法进行阵列天线方向图综合的优化设计.针对阵列天线方向图综合的特点,运用算法,通过优化单元电流幅度、阵元间距,对阵列天线方向图进行了综合优化,其中包括方向图的波瓣控制和零点生成,并同时压低旁瓣电平使其达到期望值.仿真结果表明,通过优化,天线阵的辐射特性获得很大的改善,在主瓣宽度满足要求的情况下,副瓣电平也可达到-33.6100dB.良好的仿真结果表明遗传算法在阵列天线方向图综合中的应用是有效的,有良好的应用前景.     

阵列天线的FEKO仿真分析

为在有限的硬件资源下,对复杂单元的大规模阵列天线进行有效分析,提出采用FEKO软件分析任意大规模阵列天线的有效方法. 首先应用FEKO进行相控阵分析,然后根据阵列天线的单元激励方向图(Active Element Pattern,AEP)进行阵列天线FEKO仿真分析. 实例表明,在普通硬件资源条件下,FEKO仿真分析可以在考虑单元互耦等实际因素的影响下,分析任意大规模阵列的方向图和端口特性等指标.     

基于微遗传算法的稀疏天线阵列优化方法

为生成无栅瓣、高空间分辨率的方向图,均匀平面阵列使用的天线单元数量很多,实现难度和成本高。稀疏布阵只需要相对较少的单元数目,会出现旁瓣电平升高、测向模糊等问题。通过对天线阵列特性进行分析,以全向一致、无栅瓣、低旁瓣的高分辨方向图为目标,利用微遗传算法对多重圆环阵列单元的位置参数进行优化,性能分析表明综合出的多重圆环阵列具有方位角对称、旁瓣电平低、起伏小的特点,且该算法优化效率高、收敛速度快。     

增加主瓣增益控制的阵列天线方向图综合遗传算法

阵列天线方向图综合是针对阵列天线方向图进行的相关研究中的一项基础性的研究内容。不同的应用场景中不仅需要设计形式不同的天线阵列,更需要阵列天线方向图并根据不同的性能参数指标要求进行分析优化,从而获得符合使用要求的阵列方向图。针对传统阵列天线方向图综合算法在方向图综合过程中未考虑主瓣增益约束的问题,提出了一种用于阵列天线方向图综合的改进遗传算法。在经典遗传算法的基础上设计了新的适应度函数以满足特殊情况下对主瓣增益进行约束的需求;并在算法计算过程中增加了精英保留策略,设计了随进化代数改变的交叉、变异概率。经仿真实验,结果表明所提算法能够在阵列天线方向图综合时在保证主瓣方向上的增益满足要求的同时可以获得相对低的副瓣电平水平。     

利用超宽带技术测试相控阵天线单元移相量

关于相控阵雷达天线性能优化设计中,由于某型相控阵雷达天线单元辐射器和移相器用同轴电缆连接不便于拆卸和分解,用传统的测试方法无法从辐射器端对其直接进行准确测试.设计了一种利用超宽带技术直接从辐射器对相控阵天线单元移相量进行快速测试的方法.采用耦合馈电的方式,把超宽带信号耦合馈电到天线单元上,对输出信号进行采样来测试天线单元移向状态.为了验证改进方法的可行性,搭建了超宽带时域测试系统,对相控阵天线单元移相量进行了测试.通过仿真及实验表明,在一定精度范围内,上述方法可有效对不便于拆卸和分解的某型相控阵天线单元移相量进行准确测试.     

P 波段抛物柱面天线的矩量法分析

应用矩量法对波长为0. 70 m 的P 波段抛物柱面天线进行了分析和计算, 该天线的馈源由7 元半波振子阵列构成。分析了馈源阵列偏离抛物柱面焦线时对天线增益、输入阻抗等性能的影响。计算表明, 馈源阵列沿径向向内偏离焦线时, 主要对天线的前后比产生影响, 沿径向向外偏离焦线时,对天线的主瓣和前后比都产生影响。此时, 天线输入阻抗的变化比方向图的变化明显。同样, 馈源振子直径的变化对方向图的影响较小, 而对输入阻抗的影响则较大。还对天线的波束扫描进行了模拟。     

基于凸优化的宽带阵列方向图综合算法

针对宽带任意阵列天线的方向图综合问题,提出了基于凸优化及其求解软件的方向图综合方法.其中针对宽带最低旁瓣方向图综合问题的特殊性,利用了凸优化的优良数值求解特性,以及最新的凸优化求解软件cvx时任意阵列天线的宽带最低旁瓣方向图综合算法进行了有效的建模和求解,获得了满足给定要求的宽带综合方向图.并通过详细的仿真分析验证了所提方法的正确性和有效性,而且优于当前提出的迭代算法.     

基于改进遗传算法的圆阵稀布方法

由于圆形阵列所具有的特性,使其正得到日益广泛的应用,但是圆阵方向图却具有相对主瓣较高的旁瓣电平。为此,针对稀布圆形阵列的天线单元使旁瓣电平尽量降低的问题,应用改进的遗传算法,取角度差值为染色体的基因,进行阵列孔径、单元个数、最小间隔一定的稀布优化排列,减小了遗传算法的搜索空间,提高了搜索效率。仿真结果表明:该方法能有效提高收敛速度、降低圆阵的旁瓣电平。     

PC机智能化天线方向图测试仪

本文介绍一种新研制成功的智能化天线方向图测试仅,整个系统由PC计算机、对数选频微伏表、大线转台及控制与数据采集板组成。系统自动完成转台控制、数据采集、数据处理和方向图绘制等功能,可以计算出天线波束主瓣宽度、主瓣内任一分贝电平的带宽及确定第一旁瓣位置和相对功率电平等天线参数。动态范围为60dB,转台的最小步进角达0.00625°,即22.5角秒     

声波测井圆环阵指向性设计

常规的单极子发射声波没有指向性,能量损失过多,用模态分解的方法设计出合适的阵列加权系数,就可以控制圆环阵的辐射主瓣角宽和旁瓣级,以利于在任意地层中有效激励滑行纵横波和减少能量损失.通过comsol有限元软件对圆环阵声波辐射数值模拟的例子,分析了圆环阵的辐射指向性对声波测井中各种模式波的接收幅度和到达时间的影响.结果表明,只要在圆环阵的各阵元上施加合适延迟时间合适幅度的激励信号,就能根据不同的实际情况设计出各种主声束的宽度和方向.圆环阵的使用可明显地改善声波测井的测量质量,为声波辐射器在石油勘探中的应用提供一定理论依据.     

A nonuniform array of slots in the broad‐walls of rectangular waveguides partially filled with dielectric slabs

This article describes a new nonuniform slot antenna array in the broad wall of rectangular waveguides partially filled with a dielectric slab. The slot elements are nonuniformly spaced to achieve a higher side lobe level while the amplitude and phase of their excitations are identical. Each slot element is fed by one dielectric‐loaded rectangular waveguide with one end shorted for structural simplicity. Experimental results for an 8‐element linear slot array operating at X‐band show that the side lobe level is 15 dB over a frequency range from 9.5 GHz to 10.5 GHz. The simulated side lobe level can reach 20 dB for a 16‐element linear array. Experimental results show that the side lobe level of a slot array can be improved using nonuniform element spacing without degrading the broadside radiation and gain. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

圆形基阵指向性的仿真研究

对一种适用于小型水下航行器的圆形基阵进行了研究.通过建立数学模型,对其指向特性进行了仿真,分析了影响基阵指向特性的各个因素.结果表明,与一般阵元相比,采用具有单向性与超指向性的水听器作阵元,不仪可以消除基阵的栅瓣、降低旁瓣、减小波束(主瓣)宽度,并能大大提高指向性指数,从而全面地改善基阵的指向特性;而且随着频率的降低,改善效果更为显著.采用单向性水听器作阵无的基阵在低频条件下工作更能显示其优越性.     

Design of a linear array of fractal antennas with high directivity and low cross‐polarization for dedicated short range communication application

In this article, the authors proposed an eight‐element linear array of fractal antennas for dedicated short range communication (DSRC; 5.9 GHz) service band. The single element of the array is a newly proposed fractal antenna whose radiating patch is derived from the Fibonacci series with the incorporation of Koch snowflake, and it poses a 2D quadrantal symmetry. The gain of the structure is improved by down shifting the radiating patch with respect to its ground plane. The feed network of the array is designed in such a manner to make the structure compact as well as to use the advantage of array mutual coupling for improving the array radiation pattern. The fabricated single element gives 7.54 dB gain and 128 MHz bandwidth with a radiation efficiency of η = 85.11%. The prototype array gives 15.18 dB gain with 105 MHz bandwidth and radiation efficiency of η = 72.12%. The measured cross‐polarization of single element and the array along the direction of the main beam are less than ?80 dB and ?60 dB, respectively, in both the xz‐ and yz‐plane. Both single element and the array are capable of satisfying the bandwidth requirements for DSRC applications.     

An optimal circular antenna array design considering mutual coupling using heuristic approaches

This article shows the design of a non‐uniformly excited single ring circular antenna array (CAA) for the synthesis of optimal far‐field radiation characteristics. A recently proposed meta‐heuristic based optimization algorithm called gray wolf optimization (GWO) and state‐of‐the‐art swarm intelligence based evolutionary optimization technique known as particle swarm optimization with a distribution based update mechanism (PSOd) are individually applied to determine the optimum set of current excitation amplitude weights and the inter‐element spacing among the array elements to reduce the side lobe level and 3‐dB beamwidth considering the mutual coupling. The results obtained by employing PSOd and GWO are compared to those of the uniform radiation pattern and the recently published results of state‐of‐the‐art literature having equal sets of elements to show the superiority of employed approaches. Three different design examples of 8, 10, and 12 elements CAA are reported in this article to study the performances of PSOd and GWO algorithm‐based results over the results of other recently reported literature.     

超声相控阵缺陷检测聚焦技术仿真分析

采用有限元方法对超声相控阵缺陷检测技术进行分析.首先介绍了超声波波束聚焦、偏转的基本原理,然后使用COMSOL有限元分析软件以及Matlab仿真程序对超声相控阵缺陷检测技术进行建模,在该模型的基础上分析了超声相控阵延时聚焦技术的实现过程与方法.在仿真过程中,通过改变阵元参数,研究其对于超声相控阵缺陷检测信号的影响,并结合物理实验进行了验证.分析结果表明,超声相控阵的延时聚焦技术减小了发射波的波幅宽度,提高了缺陷点回波信号的幅值;基于延时聚焦技术的发射信号,其波束指向性图的主波瓣波束较窄,幅值较高,旁瓣幅值降低,提高了图像分辨率以及成像质量.     

Design of aperiodic planar arrays for isoflux radiation in GEO satellites by applying evolutionary optimization

The design of an aperiodic planar array is presented in this research. This design of aperiodic arrays considers the reduction of the side lobe level and the isoflux radiation requirements for GEO (Geostationary Earth Orbit) satellite applications. In this way, it is considered four different optimization cases. The first two cases are optimizations of amplitude and phase excitations for the antenna elements in a uniform antenna array and the last two cases are optimizations of positions of the antenna elements and certain number of levels of amplitude excitation in an aperiodic array. In this case, it is proposed a simple new approach combining the main idea of both thinned theory and random arrays approaches. For this optimization problem, the well-known method of Genetic Algorithms (GA) is utilized. The obtained results show the proper performance of the array factor to provide the isoflux radiation and low side lobe level. Depending on the performance requirements, the design of the aperiodic array could lead the satellite hardware to be reduced significantly even more that results presented previously in the literature.     

基于模拟退火法的优化线阵的前视三维SAR模型

提出了一种基于模拟退火法的优化线阵的前视三维合成孔径雷达（SAR）模型。针对实线阵需要的阵元个数多、数据计算量大等问题,利用模拟退火法优化3D-SAR的天线阵列得到一个位置优化的非均匀稀疏线阵。分析比较非均匀稀疏线阵和几种不同结构的线阵：非均匀稀疏线阵能以较少的阵元数目达到与其他几种阵列相似甚至更好的波束分辨率,并有效地避免了均匀稀疏阵列的栅瓣问题。分析了前视三维SAR的信号模型。将位置优化的非均匀稀疏线阵应用于前视三维SAR成像并结合BP成像算法。通过仿真实验验证了该模型的正确性和有效性。     

Low‐cost and wideband circularly polarized slot antenna array

A slot antenna with wideband circular polarization (CP) array, which operates on millimeter waves band, is proposed. A four‐direction sequential rotation technique is used in the feed network to feed the 2 × 2 slot element based on waveguide. The shot element resonates at both the fundamental mode and the high‐order mode. The slot element is studied in high order mode, and the radiation lobe can be redirected by changing the size of the slot element, thus improving the multi‐lobe problem. A strong single lobe is formed in the +z‐direction by using the ground edge diffraction characteristics of the slot element in the waveguide. The designed broadband characteristics are obtained through the appropriate combination of the feed network and CP antenna. The prototype of the antenna with an overall size of 137 mm × 137 mm × 0.6 mm³ is processed and verified by experiments. The prototype of the slot array is processed and examined. The test results display that the device has good performance of |S₁₁| < ?10 dB bandwidth of 3.72 to 6.56 GHz (2.84 GHZ, 55.25%), a 3 dB axial ratio bandwidth of approximately 4.39 to 5.43 GHz (21.18%).     

Decoupling antenna array with X‐shaped strip

Manipulating mutual coupling between antenna array elements is always a critical essential in designing phased arrays. In this article, an X‐shaped strip is applied to decouple a five‐element E‐plane microstrip antenna array, whose adjacent elements' center‐to‐center spacing is only 0.45 λ₀. Simulation and measurement results reveal that the proposed array employing the loaded structure exhibits excellent decoupling capability, as in comparison to the reference array, impedance of every port is well matched, mutual coupling between both adjacent elements and nonadjacent ones is efficiently reduced and radiation patterns of every individual patch are markedly corrected. Besides, when beam scanning is performed, the proposed array is equipped with higher gain and lower SLL. The X‐shaped strip predicts a promising application in phased array and a large‐scale array.