基于粒子群算法的低副瓣螺旋天线设计

提出了一种单绕低副瓣螺旋天线的设计方法. 在单绕螺旋天线外加一个金属锥面来改变天线的辐射特性. 采用粒子群算法对影响天线方向图的参数,包括金属锥面两端的口径和长度进行了设计,以降低天线辐射方向图的最大副瓣电平. 仿真分析和实验测试结果说明在要求的1268.5±10 MHz频带范围内该天线驻波比小于1.15,天线方向图的最大副瓣电平低于-25 dB.     

Switched-beam antenna based on modified Butler matrix with low sidelobe level

A switched-beam antenna with a low sidelobe level based on a modified n/spl times/n Butler feeding network is proposed. This novel design only requires addition of 180/spl deg/ power dividers in the Butler matrix part. A four-beam prototype is constructed. Measurement indicates that the sidelobe level is significantly reduced.     

The helicone—A circularly polarized antenna with low sidelobe level

An axial mode helix in a conical horn produces a circularly polarized pencil beam of low sidelobe level over a 2-to-1 bandwidth. The gain of the combination or "helicone" is four times that of a simple helix of the same length and the sidelobes are 15 to 20 dB lower.     

数字阵列天气雷达低副瓣天线设计

为天气雷达设计一维相扫相控阵天线,方位面副瓣低于-30 d B,波束宽度小于1°,俯仰面接收副瓣低于-40 d B。方位面波束采用窄边波导裂缝阵列天线实现,采用全数字T/R组件精确控制幅度和相位,实现低于-40 d B的俯仰面接收副瓣。测试结果表明,副瓣电平与波束宽度指标与理论值吻合较好,满足指标要求。     

L波段双脊裂缝波导低副瓣阵列天线的设计

设计了一种L波段双脊波导裂缝阵列天线。该天线具有好的频率响应特性,实现了低副瓣,水平垂直两个面的交叉极化得到了有效抑制。由于馈电双脊波导的截面尺寸大幅度减小,使得这项研究将有很好的应用前景。     

High efficiency and low sidelobe design for a large aperture offset reflector antenna

A design method giving high efficiency and low sidelobes is discussed for large aperture offset reflector antennas. A new reflector shaping technique using the subreflector and the beam waveguide reflector with the parabolic main reflector is proposed to simplify the main reflector manufacturing process. The effectiveness of the technique is confirmed by the model experiments. One problem with this reflector shaping technique is that the subreflector edge level cannot be controlled independently of the main reflector edge level. By investigating the relation between the gain reduction and the subreflector edge level, which affects the wide-angle sidelobe levels, the realizable characteristics of antennas are studied. In order to decrease the subreflector edge level without reducing the aperture efficiency, a technique using an extended reflector is also proposed. Its effectiveness is shown by theoretical and experimental investigations.     

一种双扼流槽双极化低旁瓣阵列天线

设计了一种新型低副瓣双极化阵列天线,阵列单元采用角锥喇叭,利用探针分层正交馈电实现双极化辐射,利用双扼流槽解决了宽波束降旁瓣的难题.在阵列馈电设计中,利用空气同轴线网络实现泰勒加权降旁瓣设计,同时,利用反相馈电技术改善了极化隔离度和交叉极化.实测结果表明：在工作频带9.5 GHz±500 MHz,回波损耗小于-10 dB,俯仰面、方位面方向图旁瓣电平小于-16 dB,极化端口隔离度小于-30 dB,交叉极化电平小于-35 dB.     

一种空气同轴馈电的X波段低副瓣阵列天线

设计了一种应用于雷达系统中的低成本低副瓣阵列天线, 该天线阵包含256个辐射单元, 由四个64单元的子阵组成, 采用波导合成网络进行功率合成.天线单元采用空气同轴馈电的角锥喇叭, 空气同轴馈线内外导体呈方型结构, 其终端为短路馈电方式, 实现了内导体的自支撑设计和较低的传输损耗, 并依据综合幅度分布采用若干数量的不等功分器进行低副瓣设计.测试结果表明, 小于2的驻波带宽为0.5 GHz, 相对带宽为7.5%.另外, 中心频率的增益为30 dB, 增益大于29.5 dB的带宽为0.2 GHz, E面和H面的旁瓣电平为28.5 dB和29 dB.     

A low sidelobe asymmetric beam antenna for high altitude platform communications

In a communications network served by a high altitude platform, the antenna beams illuminating each cell require minimized sidelobe powers. Asymmetric beams are advantageous so that cell footprints remain circular. At millimeter wavelengths a lens antenna can have the desired properties. We have chosen a 6 km diameter cell at 32/spl deg/ elevation angle and shown how the required beam asymmetry can be implemented using an optimized polynomial for describing the lens profile. The measured average sidelobe level is below -42 dB.     

The design of antenna arrays with tapered sidelobe heights

Arrays for many radar and sonar applications have customarily been designed for equal sidelobe levels. This is, perhaps, as much due to the convenience of the analytical Dolph-Chebyshev technique as to any specific requirement. Using a simple adaptation of a previously reported numerical technique for symmetrical arrays, designs can be obtained whose directional response has a specified taper on the envelope containing the sidelobes. The method is applicable to both sum and difference patterns for both line and planar arrays. However, there seems to be little to be gained by this procedure except in the case when the outer sideiobes are to be more severely controlled.     

具备阻抗和低副瓣宽带特性的脊波导缝隙阵列天线设计

设计了一种16×8脊波导缝隙阵列天线,线阵阵面分成两个子阵,馈电采用同轴馈电与耦合缝隙馈电结合的两级馈电方式,辐射缝隙分布为泰勒分布。天线设计采用近场诊断方法和阻抗过载技术进行优化。天线实物加工测试结果表明,天线在X频段驻波带宽(VSWR≤1.5)为7.3%,最低副瓣达到-25.8 dB,副瓣电平带宽(SLL≤-19 dB)为6.2%。与已有文献相比,该天线同时具备阻抗宽带特性和低副瓣宽带特性,工作频带内具有增益均大于16 dBi的高增益特性。     

Imaging of scatterers on microwave antenna test ranges

A circular synthetic aperture imaging technique for evaluating the performance of antenna far-field test ranges is presented. Using multifrequency data, the fields incident on the region occupied by the scanning antenna are used to produce microwave images showing the distribution and level of scattering artifacts on the test site. Results are presented for S- and X-band ranges on a large outdoor antenna measurement facility. Various primary scatterers are identified, together with a source of secondary illumination of scattering objects     

Near-field blockage of an ultralow sidelobe antenna

An analytical model is presented which describes the farfield radiation pattern of an array antenna blocked by a vertical or horizontal metallic cylinder in the near field of the aperture. The implementation of this model as a generalized computer program has been completed, and the computed radiation patterns have been verified by extensive measurements on a low sidelobeX-band slotted waveguide array. The effects of the blockage are summarized graphically for a wide range of obstacle sizes and distances, and for aperture illuminations ranging from conventional reflector-type distributions to ultralow sidelobe distributions. Using dielectric or absorptive coatings to improve the radiation pattern in the presence of cylindrical obstacles is proposed as a logical extension to the existing model.     

随机误差对模块化阵列天线副瓣的影响

推导了相位误差、单元位置误差和子阵位置误差的取值范围与模块化阵列天线副瓣累积概率的关系,以及单元位置误差、子阵位置误差与整体位置误差的关系.通过实例说明,激励幅相误差、单元位置误差和子阵位置误差,对实现超低副瓣都是至关重要的.     

Measurement distance effects on low sidelobe patterns

Because of the current strong emphasis on low sidelobe antennas, the effects of measurement distance in distorting patterns are reexamined. Previous calculations have used obsolete or suboptimum aperture distributions. The Taylorbar{n}linear distribution is a versatile highly efficient and robust optimum distribution; its use here allows a single curve of sidelobe measurement error versus measurement distance (normalized to far field distance2D^{2}/lambda) for a given sidelobe level. The calculations give data from a uniform distribution to a 60 dB Taylor. For example, the first sidelobe of a 40 dB Taylor pattern is in error 1 dB at a distance of6 D^{2}/lambda.     

Contribution of reflector profile errors to antenna sidelobe radiation

The validity of a simple formula for the level of sidelobe radiation due to profile errors in an antenna reflector has been verified by numerical evaluation of Ruze's integral. The statistical distribution of the sidelobes is discussed before the formula is applied to the practical case of large earth-station antennas. Profile errors may significantly impair the sidelobe performance of these antennas unless adequate tolerances are specified.     

Fading model for antenna array receiver for a ring-type cluster of scatterers

This correspondence presents an alternate method for simulating the time-varying flat fading wireless channels for the antenna array receivers, in which the discrete ring of scatterers is incorporated around the mobile transmitter to model the spreading of azimuth. The ring-type cluster of scatterers continuously changes due to the movement of the mobile unit. Under this time-varying environment, each scatterer, at successive stages of the ring, is correlated with the scatterers at preceding stages of the ring using the second-order Markov modelling. The correlation of fading waveforms generated with the proposed paradigm is compared with the expected analytical correlation, which clearly depicts that the simulation results are consistent with the findings based on Jakes’ model.     

The effects of reflector antenna diffraction on the interference cancellation performance of coherent sidelobe cancellers

While adaptive antenna technology has undergone significant development, little attention has been given to the impact of antenna design on the performance of the adaptive system. A need exists to factor the details of the antenna system response into the analysis of adaptive system performance, particularly in the case where adaptive cancellation is required over a broad bandwidth. At extremely high frequency (EHF) where wide bandwidth allocations exist, reflector antenna technology used with an adaptive sidelobe canceller design is appropriate. This paper uses a simple diffraction model to compare the adaptive performance differences between Cassegrain and offset reflector designs. The reduced diffraction of the offset reflector design results in improved cancellation performance. These analyses also provide the opportunity to explore the impacts of antenna design parameters and interference power levels and arrival directions.     

THE LIMITATION OF MUTUAL IMPEDANCE PRECISION TO THE SIDELOBE LEVEL OF ARRAY ANTENNA

Accurate mutual coupling correction is necessary for an array antenna to reach ultra-low sidelobe level.If the mutual impedance or mutual coupling coefficient matrix of an array isperfectly known,theoretically,one can compensate the effects of mutual coupling completelyand realize the desired low sidelobe level.However,the mutual impedance matrix obtainedwhether by calculation or by measurement has limited precision,which limits the effectiveness ofcompensation.This paper deals with the requirements on the precision of mutual impedance forcompensation in ultra-low sidelobe array antennas.The relationship between mutual impedanceerrors and the amplitude and phase errors of an array is derived,by which the relationship betweenthe mutual impedance errors and the sidelobe level is obtained.     

Design of a low sidelobe double difference beam for a circularaperture

A low-sidelobe double-difference beam is synthesized for a circular aperture in a manner similar to the synthesis of the circular Taylor sum beam and the circular Bayliss difference beam. The method proposed allows the designer to select a peak-to-sidelobe level ratio and an integer N which controls the shape of the close-in sidelobes. Such a beam finds use in main beam ECCM applications