切比雪夫多项式系数特性及其在天线综合中的应用

本文证明了切比雪夫多项式系数间存在的递推关系，在此基础上定义了切比雪夫矩阵和切比雪夫变换，最后给出了切比雪夫变换在天线综合中的应用。     

考虑互耦的切比雪夫线阵天线波束形成

低副瓣是当今电子对抗时代中对雷达天线的必然要求,但由于阵列天线单元间有互耦的影响,实际的天线单元电流分布往往达不到我们设计的要求。本文在介绍切比雪夫线阵的设计公式和互耦的矩量法分析方法的基础上,首先用矩量法精确分析了考虑互耦影响时切比雪夫线阵天线阵元的电流分布,仿真实现了阵元互耦对切比雪夫线阵各阵元电流幅度及相位的影响效果以及互耦对切比雪夫线阵天线波束形成的影响效果,接下来用软件的方式补偿互耦所造成的影响,从而完成了切比雪夫线阵天线波束形成的综合。     

切比雪夫多项式系数特性及其在天线综合中的应用

本文证明了切比雪夫多项式系数间存在的递推关系，在此基础上定义了切比雪夫矩阵和切比雪夫变换，最后给出了切比雪夫变换在天线综合中的应用     

阵列方向图综合的一些方法

介绍了几种常用的阵列方向图综合方法。切比雪夫阵列在指定的副瓣电平下主瓣宽度最窄,在指定的主瓣宽度下副瓣电平最低;相位控制技术通过控制阵列各单元的相位实现波束的指向变化;最后介绍了遗传算法并利用遗传算法优化了8元线阵,将其相对副瓣电平抑制到了-50dB。     

基于遗传算法的阵列天线方向图综合

本文介绍了用遗传算法对阵列天线方向图进行综合的方法。首先利用泰勒及切比雪夫幅度分布的方向图作为优化目标进行幅度优化,验证了遗传算法用于阵列天线方向图综合的可行性。然后给出了某S波段成像雷达天线阵遗传优化结果的幅相分布曲线。最后将优化方向图与标准遗传算法综合的结果比较。结果证明文中所述方法能更好的逼近目标方向图。     

切比雪夫Ⅱ型模拟高通滤波器的设计及实现

提出了一种基于反相积分器的信号流图来实现切比雪夫Ⅱ型模拟高通滤波器的方法。首先,基于归一化切比雪夫Ⅱ型模拟低通滤波器极点分布的特点,推导出归一化切比雪夫Ⅱ型模拟低通滤波器零极点和转移函数的公式,得到归一化切比雪夫Ⅱ型模拟低通滤波器设计的步骤;然后,基于频率变换与逆变换,提出一种利用归一化切比雪夫Ⅱ型模拟低通滤波器来设计切比雪夫Ⅱ型模拟高通滤波器的方法;最后,给出了利用归一化切比雪夫Ⅱ型模拟低通滤波器来设计切比雪夫Ⅱ型模拟高通滤波器的实例及其实现电路。     

基于遗传算法与单纯形下山法的广义切比雪夫滤波器的优化设计

广义切比雪夫滤波器是一种高性能滤波器形式,用经典的综合方法提取其参数复杂且难以实现。本文以指定的电路拓扑结构和传输零点作为已知条件,结合遗传算法和单纯形下山法用MATLAB编程实现了一种新的灵活、有效的广义切比雪夫滤波器等效电路参数的优化提取方法。并给出了归一化耦合系数的物理意义及其工程应用系数转换公式。     

数字接收机中的低通滤波器设计

本文简单介绍了切比雪夫滤波器和考尔参数滤波器的工作原理和参数特性，以及在此基础上，综合设计而成的符合该接收机要求的低通滤波器。     

最佳阻抗变换器设计与应用

切比雪夫多项式在工程中应用广泛。本文对切比雪夫最佳阻抗变换的设计进行探讨,详述了何为最佳阻抗变换。以便更好地在工程中加以利用。     

广义切比雪夫滤波器等效电路参数的提取

通过对等效电路的分析,对广义切比雪夫滤波器各归一化参数的物理意义做了明确的说明,并且,在指定传输零点位置和电路拓扑结构的情况下,采用优化方法,提出了一种灵活有效的提取广义切比雪夫滤波器等效电路参数的方法。最后,用MATLAB编程实现了等效电路参数的自动化提取。     

Compensation of reflector antenna surface distortion using an arrayfeed

Various aspects of reflector surface distortion compensation are explored by first assuming the reflector distortion is given and then designing the compensating feed array. The sensitivity of boresight directivity to changing surface distortion parameters for fixed feed-array geometries is examined. It is found that feed array compensation is feasible only for distortions with low spatial frequency content, such as those distortions induced by thermal and gravitational effects. The optimum directivity methods for determining element excitation is found to yield slightly better values of directivity than those for the conjugate field matching (CMF) technique. However, the CFM technique has, in general, much lower sidelobe levels and lends itself to simple realization in hardware. In view of these results, distortion compensation using an array feed is concluded to be a reasonable approach to improving antenna performance for large, space-based reflector antennas that are not easily accessible for tuning and have time-dependent surface distortions     

平板端射阵列栅瓣抑制研究

平板端射天线通过优化产生了特殊的组阵规律即天线间距为1.5倍波长的阵列形式,该阵列形式存在栅瓣问题。本文通过提出一种解决栅瓣的途径——正交信号激励的阵列形式,建立了阵列模型,针对阵列模型开展了大量仿真计算,仿真结果证明该阵列形式可以有效抑制栅瓣,实现较低的峰值副瓣电平。     

A Design and Analysis of Dolph-Chebyshev Microstrip Planar Array Using Butler Matrix Beamforming Networks

1　IntroductionInrecentyears,personalandmobilecellularcommunicationhasexperiencedanoverwhelmingin creaseinthenumberofusers,leadingtothehugeexpansionofcellularcommunicationsystems.Theproblemsassociatedwiththeearlyusedomnidirec tionalantennasincellularcommunicationbasesta tionsarepartlysolvedbyusingsectoredantennasorcellsectorization ;thatissplittingupa 360°areainto3or 6individualsectorsormore .Thetransmittedpowerisstillnotefficientlyutilizedbecausethean tennabeamsarestillfixedindirectionanddon…     

空间不合成平板端射阵列副瓣研究

平板端射天线组阵不符合常规天线组阵规律,增益随着天线单元间距的增大而提高,在1.5倍波长时增益最高,但同时引入栅瓣问题.采用不均匀布阵抑制栅瓣,将阵元间距的稀疏约束从0.5λ栅格扩展到1.5λ栅格.经过大量仿真分析,发现当天线单元最小间距为1.5λ时,按常规不均匀阵列优化原理优化天线间距,可以抑制栅瓣但无法解决引入的高...     

Position-modulated phased array-space factor considerations

The space factor of an element position-modulated array is expressed as an Anger function series for a general amplitude distribution. The behavior of the main lobe and the diffraction sidelobes for uniform excitation are presented in the form of universal curves. It is found that the nulls near the main lobe disappear for the modulation index above a critical value. The peak level of the grating plateaus and their shapes are given in terms of approximate expressions and are exactly determined computationally. The nature of the curves suitable for design of such arrays for a given scan range and permissible peak sidelobe level is given. An example shows that a high resolution beam may be obtained with a comparatively smaller number of elements than required by a uniformly illuminated periodic array. An exact-series summation formula for the directivity of nonuniformly spaced antenna arrays of isotropic elements is given. The directivity of the modulated array computed by this formula shows a smooth variation at the ends of the scan range in contrast to the sudden fall in the case of the periodic array.     

A study of microstrip array antennas with the feed network

The radiation and losses in microstrip antennas with a corporate feed network are studied. A surface current approach is applied in which the electrical currents in the feed lines are modeled as in ideal transmission lines. The free-space radiation and the surface-wave excitation of typical segments in printed feed networks are studied. A four-element array antenna with its printed feed network is analyzed and predicted radiation patterns, directivity, and gain are presented and compared with experimental results. The gain and directivity of large arrays of 16, 64, 256 and 1024 elements are calculated and measurements in the frequency range of 10 to 35 GHz are reported     

一种新型布局的圆极化微带天线阵优化设计

提出了一款高增益低副瓣新型圆极化微带天线阵。单元天线采用叠层切角圆极化微带结构,通过八边形边界布局和顺序旋转交叠组阵技术,实现了天线阵方向性图的对称性和圆极化辐射性能的最优化;馈电网络采用威尔金森功分器和最大平坦式阻抗变换器实现不等功分宽带阻抗匹配,通过改进馈电方向寻求对称结构,简化了馈电网络的设计。制作了天线阵实物并进行了测量。测试结果表明:天线在3.2~4.6 GHz频段内S₁₁<-10 dB,阻抗相对带宽36%;在3.8~4.5 GHz频段内顶点轴比小于3 dB,圆极化相对带宽17%;在4~4.4 GHz频段内天线增益均在15 dB以上,最高增益达17 dB。     

基于遗传算法的基站天线波束赋形设计

天线阵列俯仰面方向图的赋形设计在整个基站天线设计过程中是一项关键的技术。考虑互耦以及反射板影响的实际天线阵列,选择阵列中每个天线单元的馈电幅度和相位作为优化变量,采用遗传优化算法对天线阵列垂直面方向图的下半空间零陷填充和上半空间副瓣抑制等指标进行优化,结果满足要求,具有较强的实用性。     

Adaptive antenna systems

A system consisting of an antenna array and an adaptive processor can perform filtering in both the space and the frequency domains, thus reducing the sensitivity of the signal-receiving system to interfering directional noise sources. Variable weights of a signal processor can be automatically adjusted by a simple adaptive technique based on the least-mean-squares (LMS) algorithm. During the adaptive process an injected pilot signal simulates a received signal from a desired "look" direction. This allows the array to be "trained" so that its directivity pattern has a main lobe in the previously specified look direction. At the same time, the array processing system can reject any incident noises, whose directions of propagation are different from the desired look direction, by forming appropriate nulls in the antenna directivity pattern. The array adapts itself to form a main lobe, with its direction and bandwidth determined by the pilot signal, and to reject signals or noises occurring outside the main lobe as well as possible in the minimum mean-square error sense. Several examples illustrate the convergence of the LMS adaptation procedure toward the corresponding Wiener optimum solutions. Rates of adaptation and misadjustments of the solutions are predicted theoretically and checked experimentally. Substantial reductions in noise reception are demonstrated in computer-simulated experiments. The techniques described are applicable to signal-receiving arrays for use over a wide range of frequencies.     

一种低方向性的球形共形全向天线阵列设计

传统的球形共形天线阵列馈电网络复杂,每个天线单元需要单独馈电和控制相位,导致天线阵列效 率较低。文中提出了一种采用口径耦合馈电的单馈球面共形全向天线阵。为球形天线阵列设计了一个1 分30 的馈 电网络且直接集成在了阵列内部。这样可以通过一个端口给所有的天线单元馈电,从而降低了馈电的复杂度,提高 了天线效率。阵列的方向图在x-y 平面上是全向的。x-y 平面的增益变化小于1 dB,x-z 平面的半功率波瓣宽度约为 120°,实现了比传统全向更大的空间覆盖范围。天线的方向图最大增益为1 dBi。