基于涡旋光源和相位优化的中继镜系统上行链路光束传输缩比实验研究

激光中继镜技术是一项备受各方瞩目的新型系统作战概念。光束在上行链路传输过程中,接收望远镜的截断和次镜的阻挡导致了严重的能量损耗,降低了中继镜系统的性能。涡旋光源和相位优化是提升激光中继镜系统上行链路能量效率的有效方法之一。以光源口径为1.2 m,上行传输距离为30 km,上行接收望远镜外径为1.2 m,内径为0.24 m的中继镜系统为原型,搭建了相同菲涅耳数的中继镜系统光束上行传输缩比实验装置,通过液晶空间光调制器反射调制NdYVO4光源的方法产生涡旋光源,并由随机并行梯度下降算法优化涡旋光源相位分布,开展了中继镜系统上行链路光束传输缩比实验研究。实验结果表明,通过采用涡旋光源和相位优化,中继镜系统上行链路能量效率得到了显著提高,由71.89％提升至91.59％。     

Further discrete optimizations for continuous aperture illuminations

Two applications of an iterative procedure to establish a means of optimizing theoretical low sidelobe antenna patterns are discussed. Examples described consider discrete element linear array antennas where the parameters involved in the optimization process are coefficients ordinarily associated with continuous aperture illuminations. One application uses the iterative procedure to control far-out sidelobe levels of the far-field pattern to establish array element excitations appropriate for low sidelobe behavior throughout the entire visible region of space. The other application uses the procedure to establish beam port amplitude weightings at a minimum number of beam ports in a multibeam feed network also suitable for low sidelobe antenna pattern behavior.     

Analysis of a cluster feed for the Arecibo trireflector systemusing forward ray tracing and aperture integration

A cluster feed for the Gregorian dual-reflector feed of the Arecibo radio telescope is studied. The system is analyzed by forward ray tracing from each individual feed horn via the three reflectors to the aperture. The radiation pattern is determined by aperture integration. The analysis method is very time efficient compared with physical optics (PO) integration, the latter being unusable at high frequencies because the computer time increases by a factor proportional to the frequency to the power 4. Results obtained by the ray tracing method and PO integration are in very good agreement at frequencies low enough to be used for PO calculations. A special algorithm is developed to determine the squint and directivity of an individual main beam without computing the radiation pattern. This makes it possible to use the program very efficiently when searching for optimum cluster feed geometries. The computer programs are used to design a seven-element cluster feed for the Arecibo trireflector system     

A method for producing a shaped contour radiation pattern using asingle shaped reflector and a single feed

Eliminating the corporate feed network in shaped contour beam antennas will reduce the expense, weight, and RF loss of the antenna system. One way of producing a shaped contour beam without using a feed network is to use a single shaped reflector with a single feed element. For a prescribed contour beam and feed, an optimization method for designing the reflector shape is given. As a design example, a shaped reflector is designed to produce a continental-United-States (CONUS) coverage beam. The RF performance of the shaped reflector is then verified by physical optics     

基于相位混合算法的衍射光学元件优化设计方法

在光束整形衍射光学元件的设计中,为提高目标衍射图样的重构精度,提出了一种基于相位混合的迭代算法。该算法采用复振幅每次迭代循环的初始相位与返回相位的加权和为驱动函数,并以每次循环开始和结束时的光强比较作为光束相位变换的判据。简单讨论了Gerchberg-Saxton（GS）算法的缺陷,并以高斯分布-均匀分布和高斯分布-环分布为例,对比了改进算法与GS算法的设计结果。计算机仿真结果表明,改进算法的极限收敛精度比GS算法高几个数量级,其能量利用率、顶部不均匀性等指标也均优于GS算法。该算法能获得重构精度较高的输出图样,对衍射光学元件的优化设计具体参考意义。     

Maximization of the directive gain of a parabolic reflector antenna

The directive gain of a parabolic reflector antenna is maximized by optimizing the feed aperture distribution. The feed aperture distribution is specified by a set ofNbasis functions weighted by coefficients to be determined. This approach is different from the conventional method where, given a particular feed, the directive gain is maximized by subjecting the reflector aperture parameters to optimization.     

大口径硅基空间红外透镜的高精度加工与检测（特邀）

随着红外技术的不断发展,空间大口径红外光学元件的需求日益增长,其各项制造指标也逐渐接近可见光级光学元件的制造要求,由此对新型空间红外光学元件的加工和检测技术均提出了更高的挑战。针对大口径的高陡度超薄硅基红外透镜,提出了以超声铣磨-机器人研抛-离子束精抛为工艺链路的加工方案,改善了传统红外工艺路线存在的低效率、表面高频误差等问题。针对凸非球面轮廓检测中支撑引起的测试误差,在粗抛和精抛阶段分别采用了柔性缓冲支撑与三点强迫位移支撑方法,有效解决了大口径高陡度超薄透镜测试中的支撑变形问题。经过理论仿真与实验验证,证明该测试方法具有较好的一致性。通过改进的轮廓检测方法,实现了轮廓测试中支撑误差的准确分离,有效提升了加工的极限精度。最终大口径红外透镜凸非球面加工精度达RMS λ/50 （λ=632.8 nm）,满足设计指标要求。     

Design and analysis of a multimode feed horn for a monopulse feed

The design of a multimode feed horn for use in a monopulse feed system is summarized. Both amplitude and phase patterns have been obtained and compared with measurements. The far-field amplitude and phase patterns are computed in consideration of achieving the desired aperture distributions for the sum and difference beams. The phase center of the horn is discussed in relation to the multimode excitation and frequency dispersion. It is shown that the phase center location moves as the mode content changes, and proper adjustment of the mode content will result in design optimization. Some tradeoff curves are also presented for design optimization     

Array Pattern Optimization for Steerable Circular Isotropic Antenna Array Using Cat Swarm Optimization Algorithm

In this paper the steerable isotropic circular array antenna is designed for reducing the side lobe level (SLL) using evolutionary optimization technique. The optimization techniques particle swarm optimization and cat swarm optimization algorithm are used to reduce the SLL as well as to steer the main beam in specific direction. In this design of steerable circular arrays the amplitude excitations are optimized. Obtained results show that the maximum peak of SLL of the resultant patterns are as per requirement. This paper present a good performance in the array factor response and suppressed SLL for different number of array elements with different steering angle of the main beam using evolutionary optimization technique.     

椭圆波束变焦距溅散板天线

导出了变焦距溅散板天线重要几何参数的求解方程,分析了这种天线形成椭圆波束的机理,给出了由初级馈源,介质体和溅散板所构成的综合馈源系统实测散射方向图以及根据这些散射方向图所计算的天线口面的功率等值线图。     

一种Ku波段帽型组合馈源设计分析

针对船载小口径天线的馈源设计需求,对一种新型组合馈源的馈电结构进行了模式分析,给出了一个环形口面辐射场的计算方法。通过优化提出了一个Ku频段线极化工作的组合馈源设计实例。经过CST优化仿真,组合馈源的反射板不到3个波长,且在馈源辐射波束半张角为90°时,主面边缘照射电平约为-10 dB。同时由于该组合馈源具有自支撑结构优点,因此非常适合应用于小口径、小焦径比的反射面天线。     

基于改进引力搜索算法的阵列天线波束赋形

提出了一种改进引力搜索算法,通过引入遗传算法的变异算子,提高了引力搜索算法的局部搜索能 力,解决了引力搜索算法在阵列天线赋形波束应用时的实现方法和早熟收敛问题。在阵元个数及阵元间距一定的 情况下,对阵元激励的幅值和相位进行优化,使赋形波束达到设计要求。实验结果证明了该改进方法的可行性和有 效性。     

纵向槽和径向槽组合波纹喇叭馈源的优化设计

研究了纵向槽和径向槽组合的波纹喇叭馈源的优化设计方法.基于旋转体时域有限差分算法分析波纹喇叭的性能,结合协方差矩阵自适应进化策略,以天线口径效率为目标,优化设计了一款Ku频段波纹喇叭馈源,并加工和测试了馈源样机.计算与实测结果表明,在10.7~12.75 GHz频带内,该喇叭具有良好的阻抗匹配和辐射特性,应用于标准卡塞格仑天线时,天线口径效率优于78%,验证了这种优化设计方法的有效性.     

卫星反射面天线波束赋形的研究

卫星波束赋形天线普遍采用阵馈抛物反射面天线和单馈成形反射面天线。针对前者阵馈和后者反射面表面形状复杂的特点,本文分别采用了遗传算法和共轭梯度法对这两种天线进行了优化,并获得了中国版图的波束赋形,说明上述算法在卫星反射面天线波束赋形优化中是有效的。     

共享孔径同心圆阵稀疏交错优化布阵方法

同心圆阵列天线具有波束对称、360°方位角扫描、抗干扰能力强等优点，被广泛应用于星载、机载、舰载雷达及飞机声呐等领域。在天线孔径有限的情况下，如何进一步提高同心圆阵的孔径利用率，通过孔径的空分复用，设计出子阵稀疏交错分布的多功能同心圆阵列天线，具有较大的研究价值。利用均匀同心圆阵列天线激励与方向图函数存在二维傅里叶-贝塞尔变换关系，基于二维三次插值和密度加权，提出了一种同心圆阵稀疏交错优化布阵的方法。该方法通过对均匀同心圆阵列天线方向图采样值的频谱能量进行分析，采用三次插值的方法，实现了同心圆天线阵列方向图函数到同心圆阵元激励能量的映射转换；基于密度加权的原理，对排序后归一化阵元激励的奇偶交错选取，使得稀疏交错子阵方向图频谱能量均分匹配，实现了同心圆阵的稀疏交错优化布阵设计。仿真结果表明，该方法得到的交错子阵天线具有峰值旁瓣电平低、主瓣宽度窄且方向图性能近似程度高的优点，有效解决了同心圆阵列天线稀疏交错优化布阵的设计难题，实现了两子阵交错的共享孔径多功能同心圆阵列天线设计。     

Reflector radiation pattern from planar near-field measurements of array feed

High gain shaped beam antennas for satellite frequency reuse applications are almost exclusively obtained by the use of complex multielement feed arrays to provide pattern control in conjunction with offset reflectors to remove blockage effects. In the design of complex multielement feed arrays for offset reflectors, the element excitations are usually synthesized using the isolated element properties. Proper performance of the array often requires that these theoretical excitations be modified to account for the effects on the feed elements due to the array environment. Near-field planar probing of the fields of the feed array have been found to provide an efficient and accurate method of predicting the secondary performances, including cross polarization and axial ratio. The nearfield measurement technique, moreover, provides an extremely effective method of determining the element performance and for determining the required compensation for desired antenna performance.     

基于投影矩阵法的阵列天线波束形成方法

该文介绍一种阵列天线波束形成的新算法投影矩阵法,包括复系数、仅相位、仅幅度的波束形成技术,并推广应用到多目标波束综合设计中。文中首先给出采用投影矩阵法进行阵列天线复系数和仅相位波束形成的计算方法,然后提出仅幅度控制下的投影矩阵法,并进一步应用到多目标波束同时优化设计中。该文计算了多种工程应用例子,特别是满足全口径和多子孔径波束优化的仅幅度控制技术、满足多波束优化的仅相位控制及共用幅度优化技术,对算例的设计达到了采用优化激励系数控制波束指向、波束赋形、旁瓣电平等性能要求,实现了阵列天线的波束形成。仿真结果说明了投影矩阵法的有效性,适用范围广泛。      

Development of a 45 GHz multiple-beam antenna for militarysatellite communications

Design and experimental results of a wide-angle coverage 45 GHz multiple-beam antenna for military satellite communications are presented in this paper. The high-gain spot beams with low sidelobe levels and efficient adjacent beam overlap are generated by employing an offset parabolic reflector with overlapping feed clusters. The beam shape can be adapted to cancel either single- or multiple-jammers by varying excitations within the feed cluster corresponding to the beam. Development of antenna components including Potter horn, polarizer, phase-amplitude controller, and beamforming network is discussed. Measured results of the demonstration antenna have shown that sidelobe and crosspolar levels of better than -25 dB are achieved for beams scanned over an eight-degree diameter circular coverage region. The adapted patterns of the antenna agree well with the computations, and null depths of better than 30 dB have been realized over a 4.5% bandwidth     

Element Failure Correction for a Large Monopulse Phased Array Antenna With Active Amplitude Weighting

Recently a new method is introduced to synthesize low sidelobe patterns for planar array antennas with a periodic element arrangement. The method makes use of the property that for a planar array with periodic spacing of the elements, an inverse Fourier transform relationship exists between the array factor and the element excitations. This property is used in an iterative way to derive the array element excitations from the prescribed array factor. The same method is also able to partially compensate the degradation of the sidelobe and gain performance of array patterns due to element failures. Numerical examples of array-failure correction using this method are given for ultralow sidelobe sum and difference patterns of a 5800-element circular array where the failed elements are randomly dispersed across the aperture. The tapers in this array are created exclusively by active weighting in the transmit/receive (T/R) modules using variable gain control.     

光寻址液晶空间光调制器用于激光光束整形的可控系统和设计算法

提出了一种利用光寻址液晶空间光调制器(LC-SLM)来实现实时可控的激光光束整形的系统和算法.用几何变换法和盖师贝格-撒克斯通(G-S)算法对有振幅调制和位相畸变光束进行均匀分布的平顶光束整形及数值模拟,用几何变换法可以得到非常好的小尺度的均匀性输出光束,而G-S算法能够有效地改善入射光束的大尺度不均匀性.为了减少输出光束的均方根误差和顶部不均匀度,提出结合几何变换方法和G-S算法,由几何变换方法得到的相位分布为G-S算法的初始相位分布.计算机设计的仿真结果表明:利用这种算法可以有效减少大尺度的不均匀度值,并得到合适的输出光束.