有源相控阵雷达天线实时校正方法

针对有源相控阵天线的超低副瓣、高增益及精确波束指向等性能的实现进行分析研究。首先分析一般相控阵雷达天线及其校正耦合网络的结构,并对实时校正的原理以接收校正为例进行详细的阐述,最后通过某有源相控阵雷达天线实测数据验证该方法的有效性及可行性。     

Beam tagging for control of adaptive transmitting arrays

Conventionally, self-focusing or steering of an adaptive array has always been controlled by signal measurements made in the receiving mode. By the use of beam tagging, a transmitting array can be made adaptive. The signal from each array element is tagged with identifying modulation, and a single sample from the far field can then be analyzed to find control information for the set of transmitting-element phases and amplitudes. The technique can be used with two-way (transmit-receive) arrays or with arrays used solely for transmitting. It can also be used in combination with conventional techniques for controlling adaptive arrays.     

一种新型圆极化可重构天线

本文利用最大功率传输效率法(MMPTE),通过4个相同左旋圆极化贴片单元作为子阵来实现阵列天线圆极化可重构。通过在被设计阵列(作为发射阵列)远场区引入极化控制接收天线,可以将整个收发系统看作一个无线功率传输系统,这样就可以把阵列天线的设计问题转换为一个天线之间的传输效率最优化的问题。通过调节接收天线的极化方式和接收位置,可控制被设计阵列的极化方式和扫描角度。与传统做法不同的是,被设计阵列单元的极化方式确定时,通过改变接收天线的极化方式,阵列还能产生与单元极化相反的极化方式,同时两种极化方式所得的增益差距在1dBi以内。本文以中心频率在2.45GHz的左旋圆极化单元组成的十六单元阵列为例,说明如何实现阵列左右旋极化的可重构以及+/-60°的扫描功能。     

Construction of a slot-coupled planar antenna for dual polarisation

A new type of feeding technique for a dual polarisation antenna is presented. The proposed feeding system was experimentally investigated for both a single element antenna and basic planar array antenna. This antenna system demonstrated high performance in both isolation characteristics and radiation patterns     

Dual-loop slot array antenna radiating circularly polarised wave

An array antenna consisting of dual-loop slot elements with a simple feeding system is realised. Each dual-loop element has two loop slots that are simultaneously fed by a single triplate transmission line. A narrowed beam, of circular polarisation, with an axial ratio of less than 3 dB, is obtained over a 3% bandwidth. The measured radiation pattern agrees well with a pattern calculated using array theory.<>     

Printed antenna and array with circular polarisation

A new type of printed antenna element, as well as an array of elements with circular polarisation, is shown. The antenna has a much wider bandwidth than known circularly polarised printed antennas, mostly microstrip patches. The method of design and realisation with experimental results is shown     

Dual polarisation of microstrip reflectarray antenna

Dual polarisation of a microstrip reflectarray was demonstrated for the first time. A 16 element array of square microstrip patch antennas operating in the X-band was used to reflect the main beam 20" off broadside in both the E-plane and H-plane     

Conformal array synthesis using alternating projections, with maximal likelihood estimation used in one of the projection operators

A technique is described for the synthesis of conformal arrays. Account is taken of the effect of individual element patterns and polarisation in the presence of the host surface. The application of the method to the case of a linear array of slots on a circular cylinder is discussed.<>     

相控阵孔径级同时收发技术研究

传统同时收发技术主要针对无线通信中的单元级天线配置进行研究,文中以大规模阵列作为研究对象,研究针对孔径级的收发同时技术,实现了大规模相控阵体制下的收发隔离。结合自适应阵列加权和收发隔离技术,以拉格朗日乘子法获得最优加权矢量。通过最小化耦合信号、最大化期望方向增益来构造代价函数,求得在线性约束最小方差准则下的最优权值。结果表明:在不影响目标检测性能的情况下,该方法能提供110 dB以上的隔离度,具有一定的工程参考意义。     

Broadband printed ring-slot array with circular polarisation

A novel design of a printed ring-slot antenna with circular polarisation (CP) is first proposed. The CP radiation of the slot antenna is achieved by a series microstrip-line feed configuration. Using the single CP slot antenna as an array element, the 1times2 and 2times2 slot arrays are constructed and measured. To obtain wider CP bandwidth, phase sequential rotation technique is applied to the feed network of these printed slot arrays. The experimental results show that the 2times2 slot array antenna is capable of 15% bandwidth for an axial ratio of less than 3 dB     

Polarisation switchable microstrip array antenna using proximity feeding technique

A polarisation switchable microstrip array antenna is presented. This array consists of square patch antennas coupled in close proximity to a microstrip line. The polarisation state can be switched electrically by short- or open-circuiting the end of the feedline using a PIN diode. Fundamental characteristics of the proposed array are investigated by measurements performed at S-band to demonstrate the proposal.     

Spiral antenna with coplanar strip line feed

A low-profile spiral antenna composed of a small number of turns is developed as a radiation element for circular polarisation. The spiral is fed without a balun circuit from a coplanar strip line located in the middle of two conducting planes. The upper plane has a circular aperture for the spiral to radiate. The spiral arm is optimised for 11.85 GHz. An array antenna consisting of four spirals is fabricated and the radiation characteristics are presented.<>     

Investigation of an ultrasonic monopulse image restoration method

An algorithm for reconstructing the image of the region sensed by a plane single-pulse wave is synthesized (as a particular case of a general solution) and investigated. Reflected signals are received by a planar array of sensors (transducers) that generates the sensing wave. The influence of the sensing signals’ waveforms and the configuration of the transmit-receive array of transducers on the image quality is analyzed. The results of numerical simulation are presented.     

X-band brick wall antenna fed by CPW

A brick wall antenna fed by a coplanar waveguide is introduced. This antenna can be considered as an eleven element array of reduced size. Analysis is carried out both theoretically and experimentally. The proposed antenna is designed to work in the X-band ~9.5 GHz. The return loss, radiation pattern, and antenna gain of the proposed antenna are presented and briefly discussed. The antenna has several advantages, such as ease of fabrication, good control of input impedance, small cross polarisation level, and high directivity     

Circularly polarised radiation from narrow wall slots in rectangular waveguide

Slots in rectangular waveguides are often used at elements in linear array antennas. The polarisation of the radiated energy is usually linear. Circular polarisation can be obtained with compound slots in the broad wall. Experiments have shown that circular polarisation can be obtained from certain I-shaped slots in the narrow wall.     

Circularly polarised patch antenna array using proximity-coupledL-strip line feed

A microstrip antenna array for circular polarisation (CP) using a proximity L-strip line feed is proposed and experimentally investigated. By placing a cross-slot with unequal slot lengths on the circular patch, circular polarisation can be excited. Also, a sequential rotation technique is adopted for the design of this CP antenna array to widen the bandwidth. The impedance and axial ratio bandwidth values are 78 and 16.15%, respectively. The boresight axial ratio is 0.4 dB at 1.91 GHz     

一种基于四相编码和优化阵列的MIMO STAP实现方法

多输入多输出（MIMO）雷达多信号间正交性和天线阵列结构影响空时自适应处理(STAP)性能。为了提高多信号间正交性,提出了基于遗传算法优化提高四相编码的自相关峰值并降低互相关峰值方法,保证了多发射信号间良好正交性,基本抑制了盲速影响。针对天线阵列稀疏导致盲速、阵元密布导致天线孔径过小的问题,基于最大连续孔径思想,提出了一种优化阵列结构,在不显著增加天线阵列长度和阵元数目条件下,与四相编码信号结合,实现了动目标检测。仿真实验证明,基于四相编码正交信号和收发阵列设计,MIMO STAP可实现良好动目标检测性能。     

基才多相编码和收发阵列设计的机载MIMO雷达STAP方法

针对提高MIMO雷达多信号间正交性问题．提出了基于遗传算法优化提高多相编码信号自相关峰值、降低互相关峰值方法,提高多发射信号间正交性,降低盲速影响。针对天线阵列稀疏导致盲速、阵元密布导致天线孔径过小问题,从等效天线特征出发,给出了一种发疏收密阵列结构,与多相编码信号结合,进行动目标检测。仿真实验证明,基于多相编码正交信号和收发阵列设计。MIMO STAP可实现良好动目标检测性能。     

Four-element varactor diode loaded polarisation-agile microstripantenna array

A square, varactor diode-loaded polarisation-agile microstrip patch, radiating either circular polarisation (left or right hand) or linear polarisation (in two orthogonal planes) is described. A linear array comprising four such patches has been designed. Measurements show, when operated in circular polarisation, axial ratios better than 0.5 dB and, in linear polarisation, cross-polar levels better than -20 dB     

基于俯仰频率分集技术的波束形成方法

传统频率分集阵列雷达在水平阵元间引入线性频率偏差,其波束在方位维与距离维具有耦合性,且存在栅瓣。针对此问题,该文提出一种基于俯仰频率分集技术的波束形成方法。首先建立俯仰频率分集阵列雷达信号模型,详细分析了发射方向图的时间依赖性和栅瓣特性。然后通过设计接收端的阵元参数,合成无栅瓣的发射-接收方向图。仿真实验验证了所提方法的有效性,所得波束在距离维与方位维无耦合,且主瓣宽度较窄。