Polarisation control of a loop antenna by PIN diodes

A wire loop antenna with two electronic switches is introduced to control polarisation (left-hand, right-hand or linear polarisation). The loop is fed through an electromagnetically coupled monopole antenna. The loop and the monopole are located on a ground plane. The switching circuit with PIN diodes is installed near the feed point of the monopole to obtain symmetric radiation patterns. Good axial ratio and impedance characteristics are obtained. The experimental results show the capability of the polarisation control by electronic switches     

圆极化高温超导微带天线阵

在0．62mm厚的MgO衬底上,设计和制造了一个用于直接广播卫星（DBS）系统的圆极化和单一馈电网络的四单元高温超导微带天线阵,中心频率为12．2GHz。为了比较,一个天线采用金膜制造,另一个采用超导薄膜钇钡铜氧（YBCO）制造。为了提高圆极化阵的轴比特性,运用连续旋转技术,分别在室温和液氮温度下测试效率、方向性、回波损耗和带宽。采用超导薄膜钇钡铜氧（YBCO）制造的阵表现出很好的圆极化特性,在77K时的增益比室温时的金膜天线阵大1．64dB。在谐振频率12．24GHz时回馈损耗为-30．6dB,总有效带宽约为3．52％,表明当高温超导体用于微带天线阵时,能提高天线阵的效率。     

Second-order discriminant function for amplitude comparisonmonopulse antenna systems [EW antenna array]

The technique of using three receiving elements for amplitude comparison monopulse direction finders (DF) is examined. An appropriate second-order discriminant function is chosen for this technique. Simulation is then used to compare the system performance to that of the two-element system. In performance evaluation, errors coming from receiver noise, antenna pattern, amplitude imbalance, and mechanical and quantization origins are accounted for     

General synthesis method for linear phased antenna array

An efficient phase-only control method is presented to synthesise directive lobe and multilobe patterns, and create adaptive nulls in interference direction. The proposed method is based on iterative minimisation of a function that incorporates constraints imposed in each direction with respect to excitation phases. To verify the performances of the proposed technique, an eight-element array has been realised and tested for various types of beam configurations.     

Microstrip antenna array controlled with active phase shifter

Abstract

A two‐element microstrip antenna array controlled with active phase shifters has been fabricated and tested. The phase and amplitude of the active phase shifter output can be continuously changed by controlling the gate voltages of the dual gate FET. This array can be mounted on aircraft or missiles and be used in the direction finder or adaptive array systems.

The mutual couplings between microstrip patches are also experimentally studied. It is found that the self‐impedance and resonant frequencies depend highly on the separation if the patches are separated less than 0.4 wavelength and become constant as the separation is greater than 0.5 wavelength. The effect of mutual coupling in the E‐plane is less prominent than that in the H‐plane. In array patterns synthesis, the mutual coupling can be neglected if the separation is greater than 0.5 wavelength. However, if the separation becomes smaller, the mutual coupling must be considered such that the calculated patterns are in good agreement with the experimental results.     

一种多波束可旋转的金属波导太赫兹阵列天线

随着移动通信的高速发展和通讯环境的日益复杂,多波束天线在多目标雷达、卫星通信以及多点无线通信等领域有着广泛的应用需求。轨道角动量是电磁波的基本属性之一,它具有螺旋形波前,可独立于振幅、相位、偏振等基本属性,能为电磁波提供新的复用维度。基于亚波长金属波导阵列对电磁波优异的调控能力,我们设计了一种多波束可旋转的太赫兹(THz)阵列天线,通过调控入射波两正交偏振分量的相位分布,可将其分别转化成强度分布一致、阶数相反的涡旋波束。通过改变两分量的相位差,可实现45°偏振方向上波束的干涉图样发生旋转。此外,该阵列天线还展现出了高增益(31 dBi)和宽带宽(61 GHz)的特性。该工作可为基于多波束阵列天线的方位角测量提供新的思路,对丰富THz频段的阵列天线设计具有重要意义。

     

Dynamic null steering in an ultrawideband time-steered array antenna

We develop a method for forming squint-free wideband nulls in the antenna pattern of an ultrawideband array antenna. The technique uses an optical dispersive-prism beam former to provide time-delayed microwave signals to each antenna element for forming a squint-free main beam. The amplitude-modulated optical carrier is propagated through a set of optical links. Each link feeds an array element and includes an amount of dispersion proportional to element position. Tuning the wavelength of the optical carrier controls the microwave signal's arrival-time delay gradient across the array. A dispersive-prism tapped delay-line microwave filter is used to frequency shape a nulling signal. The wideband nulls do not significantly distort the main beam and are steered independently of the main beam. The technique is applied to sidelobe nulling for a transmitter and for jammer suppression for a receiver array.     

新型折叠卷收式反射阵天线的设计与制作

 设计了一种新型折叠卷收式反射阵天线,减少了天线展开前的质量和体积．为了使反射面得到最好的平面精度,从理论上证明反射面的边界形状应当为圆形．给出了悬索详细的设计计算方法．在此结构中使用了一种新型的、通过钢卷尺强化的充气可展开铝箔圆管．通过非线性屈曲分析,研究了钢卷尺的厚度、圆心角角度以及铝箔厚度等因素对圆管承载力的影响,并通过实验验证了非线性屈曲分析结果的正确性．最终制作了这种新型天线,并对其展开后的形面精度进行了测试,实验证明此种新型天线完全可以满足反射阵天线的精度要求．     

Frequency-invariant pattern synthesis of conformal array antenna with low cross-polarisation

Despite their potential and promising advantages over classical planar arrays, conformal arrays also present many challenges to the antenna designer, including varying element normal due to curvature, serious cross-polarisation effect, limited operational bandwidth and so on. A uniform method for the element polarised pattern transformation of arbitrary 3D conformal arrays is presented based on Euler rotation. A space-time-polarisation filter structure is proposed for the pattern synthesis of conformal array, in which the finite impulse response (FIR) filters assigned to every element are used to acquire the frequency-invariant array pattern and the element polarisation diversity in array global coordinates is used to depress the cross-polarisation level. The optimal weight vector is obtained by alternating projection method. The alternating projection method is a powerful and attractive method for the pattern synthesis in that it requires relatively smaller amount of computation burden and a wide variety of desirable constraints can be freely implemented in a -visible- way, which is usually impossible for other optimisation method. The pattern synthesis method proposed has established a unified frame for the frequency-invariant and low cross-polarisation pattern synthesis of conformal array. Simulation results are provided to demonstrate the effectiveness and behaviour of the proposed method.     

大阵面天线液压折叠技术研究与实现

为了实现对大尺寸平面阵列天线的公路和铁路快速运输,把大阵面天线分割成相互独立而又连接的上下2个阵面.系统采用液压控制技术和伺服控制技术,以液压回转缸作为天线展开/折叠的驱动执行机构,以可编程控制器PLC为伺服控制器,实现天线自动展开、折叠与锁固.试验及实践表明:该系统性能稳定,操作简单,阵面重复面精度高,锁定简单可靠,具有广阔的应用前景.     

Phase-only adaptive nulling with neural networks for antenna array synthesis

A new approach to adaptive phase-only nulling with phased arrays is described. An efficient method is presented to synthesise directive beam and multi-beam patterns and create adaptive nulls in interference direction. The proposed method is based on iterative minimisation of a function that incorporates constraints imposed in each direction with respect to excitation phases and neural network technique. Various results are presented to show the advantages and limitations of this approach. The back-propagation algorithm proves to be better than previous phase-only adaptive algorithms. To verify the performances of the proposed technique, an eight-element array has been realised and tested for various types of beam configurations.     

Omnidirectional 3D nanoplasmonic optical antenna array via soft-matter transformation

Inspired by the natural processes during morphogenesis, we demonstrate the transformation capability of active soft-matter to define nanoscale metal-on-polymer architectures below the resolution limit of conventional lithography. Specifically, using active polymers, we fabricate and characterize ultradense nanoplasmonic antenna arrays with sub-10 nm tip-to-tip nanogaps. In addition, the macroscale morphology can be independently manipulated into arbitrary three-dimensional geometries, demonstrated with the fabrication of an omnidirectional nanoplasmonic optical antenna array.     

Sectorised antenna array and measurement methodology for indoor ultra-wideband applications

A new sectorised antenna array (SAA) and measurement methodology are proposed for indoor ultrawideband (UWB) applications. The proposed SAA comprises of one centre element and six side elements. The one centre element and six side elements are arranged in a semi-spherical antenna array configuration. The measurement system and methodology for the coverage of the SAA are developed. The measured bandwidth of the SAA for voltage standing wave ratio (VSWR) <2 is 37.5%, ranging from 3.06 to 4.47 GHz. The boresight gain is more than 5.2 dBi across the impedance bandwidth. The proposed SAA is able to provide omni-directional pattern with an average gain of 5.2 dBi over the angles (0-3608). The discone reference antenna is used to measure the coverage of the proposed SAA. The proposed measurement study shows that the proposed SAA offers omni-directional coverage desirable in UWB indoor location and short-range communication systems.     

Wi-Fi/WiMAX双极化阵列天线研究

提出一种应用于Wi-Fi/WiMAX的宽带高增益双极化阵列天线.它由+45°和-45°正交极化的两个天线组成。当频率为2.38~2.72 GHz时,天线的回波损耗大于-10 dB;端口1与端口2之间隔离度大于20 dB;端口1在2.45 GHz时获得最大增益为17.14 dBi,端口2在2.483 GHz时获得最大增益为17.15 dBi.仿真和测试很好相吻合,该双极化天线能满足Wi-Fi/WiMAX通信网络要求.     

基于阵列分解的星载相控阵天线波束成形网络设计

根据"子阵列"理论,对星载阵列相控阵多波束天线的阵元空间和波束空间进行子阵分割,分析天线阵元空间成形系数的复用情况,并结合分布式算法,在阵列分解基础上提出了一种波束成形网络的复用结构,节省了67%以上的资源。最后实现了波束成形网络的试验验证平台,并完成了算法的移植和验证。结果表明,该波束成形网络比常规方法节省了大量资源,并实现了多波束等通量覆盖的设计目标。     

Eigenspace-based blind pattern optimisations of steerable antenna array for interference cancellation

A novel adaptive algorithm for an array using directional elements called a hybrid smart antenna system is proposed. The algorithm controls the element patterns on the basis of an objective function composed of eigenvalues of a covariance matrix. A high and stable array output signal-to-interference-plus-noise ratio is achieved by improving both the received powers and the spatial correlation coefficient between incident waves, without prior knowledge such as directions-of-arrival, channel state information or training signals. The characteristics of the proposed algorithm are theoretically and numerically clarified for a simple case involving two incident waves. Convergence with least mean squares algorithm is found to be as fast as that with recursive least squares algorithm in this system. Also, simulation for statistical performance evaluation is carried out in comparison with a conventional system. Furthermore, a method to implement the proposed eigenspace control algorithm without having to solve the eigenvalue problem is shown.     

一种相控阵雷达天线极化特征的外场测试方法

为了解决相控阵雷达天线极化特征的外场测量问题,研究了极化的幅相测量法和斜天线测试场的布局方法,设计了基于双通道接收技术的相控阵雷达天线极化特征的一种外场测试方法。给出了应用该种方法的测量装置、测量布局、测量内容、测量步骤,分析了测量误差。该种测试方法在相控阵雷达天线极化特征测试任务中得到成功应用,为某武器系统的研制提供了准确的测量数据和宝贵的研究资料。     

Diagnostics of a short-wave transmitting antenna array in the near-field zone

An electrodynamic calculation is presented of the field of an antenna-feeder device. This calculation is used as the basis for proposing a diagnostic method for determining the operation of a feeder device in which probes are introduced into the aperture zone of the antenna. The diagnostic signals measuring the state of the feeder are considered together with an algorithm for processing them. Translated from Izmeritel'naya Tekhnika, No. 1, pp. 41–48, January, 2000.     

阵列天线CDMA系统用户相干多径信号波达方向估计

提出了一种适用于阵列天线CDMA系统用户相干多径信号波达方向(DOA)估计的有效算法.该算法巧妙利用CDMA系统用户扩频序列的先验知识和特性,对用户相干多径信号进行解扩和匹配滤波处理,实现了对用户多径信号的有效分离和对多址干扰的抑制,对解扩后的用户多径信号采用DOA估计的综合方法进行波达方向的估计,对N元阵列,可同时估计出任一用户2N/3个相干多径信号的DOA.仿真结果表明该算法十分适合应用于CDMA类移动通信系统用户相干多径信号的波达方向估计.     

Impact behavior of composite antenna array that is conformed around cylindrical bodies

In this paper, one structurally integrated array that is conformed around cylindrical bodies has been designed and fabricated for a part of the aircraft outer skin. The effects of the mechanical topology are considered in the antenna design, confirming the optimal integration without compromising either the mechanical or the electrical performance. The measured results show that the radiation pattern is strongly dependent on the radius of curvature. The results of a study of the response and failure characteristics subjected to low-speed impact damage are presented; they indicate that the value of the contact force decreases as the radius of curvature decreases. As the impact energy was increased, the specimens experienced significant damage consisting of a dent localized in the region of impact. These results suggest that the radius of curvature is an important electrical and mechanical parameter in the design of conformal arrays.