Multibeam planar arrays

The application of general N-port Butler matrices to the generation of multiple beams-from planar arrays is described. It is shown that the array must satisfy a "covering" condition. The interconnection of array and matrix is derived. The method, for determination of beam position is developed and applied to rectangular arrays to improve beam crossover level. Examples are presented.     

Optimization of planar arrays

A method is developed for maximization of the gain of a planar array at a prescribed sidelobe level. The method is iterative and includes a quadratic programming routine. Numerical examples are given for an octagonal array with a quadratic array lattice and for hexagonal arrays with triangular lattices. The latter arrays are compared to the results obtained by sampling the circular Taylor distribution.     

Synthesis of sparse planar arrays

A synthesis method is proposed that is aimed at designing a planar, sparse, and aperiodic array to be used in a beamforming processor. This method minimises the number of elements able to generate a beam pattern that fulfils various a priori fixed constraints. The obtained results are better than those proposed in related literature     

Liquid-crystal polarization controller arrays on planar waveguidecircuits

In this letter, we have developed thin liquid crystal (LC) arrays for use as simple polarization-controller arrays on planar lightwave circuits (PLCs). The 30-μm thick LC arrays are vertically inserted into trenches cut across PLC substrates. Two such LC cells that are in line and parallel to each other, one of which has a direction of alignment that is rotated by 45° relative to that of the other, are able to convert an arbitrary input polarization to a desired one. Twisted-nematic LC cells can switch the polarization of input light between the TE and TM modes with an extinction ratio of 15 dB     

Quasi-optical planar arrays with FETs and slots

This work describes the design concept and experimental results for prototypes of two-dimensional quasi-optical power-combining arrays. Several different quasi-optical circuits were used to obtain the fundamental data for this study. How to incorporate the antenna input impedance into the active antenna circuit and how to analyze the strong coupling condition with two operating modes are addressed using large-signal analysis. Several circuit configurations are demonstrated, including a single active antenna operating at 9.3 and 24.0 GHz, a six-element linear power-combining array operating at 15.6 GHz, and four-element and sixteen-element two-dimensional power combining arrays operating at 10.4 and 7.8 GHz. Important characteristics such as antenna patterns and tuning ranges are discussed. The prospects for a two-dimensional monolithic quasi-optical power-combining array are discussed     

平面FSS阵列的一维截断效应

基于互导纳法进行有限频率选择表面(FSS)计算分析,研究狭缝阵列一维截断时磁流分布、散射方向图及传输特性的变化,考察了单元列数、入射角等因素的影响.与无限平面阵列相比,截断导致边缘单元磁流分布起伏,部分频率产生表面波,散射方向图波束展宽且副瓣电平升高,功率透射系数发生变化,仅谐振频率和传输带宽与无限平面阵列基本相同.     

Evaluation of directivity for planar antenna arrays

In this paper, the directivity, including phase shift factors, for several types of uniformly excited planar arrays is obtained. Four types of dipole arrays are considered: arrays of collinear short dipoles, and of parallel short dipoles; and broadside and end-fire arrays of crosses of short dipoles. Curves of directivity versus inter-element spacing and scan angle for planar arrays with these element power patterns are presented     

平面相控阵宽角扫描技术

平面相控阵天线的宽带、宽角扫描理论与技术是当前天线电波传播领域的核心课题与关键技术,对高性能雷达、通信、导航等信息系统起到重要支撑作用. 研究表明,制约平面相控阵天线宽角扫描的瓶颈主要有：单元的波束形状、阵列排布方式以及扫描阵列中的耦合关系. 据此,本文将从以上三方面回顾平面相控阵宽角扫描理论与技术的发展历程,并对其研究发展做出展望.

     

Performance analysis of planar hybrid matrix arrays

An analysis is presented of overall aperture efficiency, weight, and control power requirements for hybrid matrix arrays in synchronous satellite applications. An array is described which is mounted on a 7-foot aperture in a triangular grid fashion and fed by a hybrid matrix consisting of 3-port building blocks which in turn are fed by 9-port matrices. The beam crossover loss is minimized by beam combining at the outputs of the 9 ports. Component losses are analyzed, and residual array gains are calculated for the 7-foot aperture as a function of operating frequency. It is concluded that arrays of this type are practical for net gains of up to 30 dB.     

An experimental study of collinear and planar arrays

Measurements are described that serve to verify a recently reported new theory of arrays of arbitrarily located parallel elements especially including ones that are collinear and staggered. Since the theory takes full account of the effects of mutual coupling in determining the distributions of current in each element of an array, the experimental studies involved the determination of distributions of current and charge as well as admittances and field patterns. Since the theory should be a good approximation for dipole elements well over a wavelength long, complete measurements are reported for arrays of both half-wave and full-wave elements in collinear and planar arrangements. Experimental and theoretical results are in good agreement.     

Matrix pseudo-inversion technique for diagnostics of planar arrays

It is shown, by means of numerical simulation, that the Moore-Penrose pseudoinverse of a matrix taken from an overdetermined system can be applied to retrieve the excitation distribution of a planar array of parallel dipoles with faulty elements, by measuring the complex radiated field in its near zone. Failures on voltage (considering mutual coupling) and current of several elements, and systematic or random measurement errors, are considered in the simulation.     

Difference pattern synthesis in small planar phased arrays

A pattern synthesis technique for low sidelobe arbitrarily scanned difference beams in small planar phased arrays is presented. The approach is based on adaptive array theory and is the development of a technique used for radiation pattern synthesis in linear arrays. The method has been applied to measured element pattern data from a small planar array, which includes the effects of pattern corruption by mutual coupling. The successful synthesis of low sidelobe difference beams is demonstrated, with arbitrary difference plane and scan angle     

Synthesis of planar arrays based on convolution technique

A noniterative synthesis technique for planar arrays with arbitrary triangular lattice is described. The method, using a convolution process, synthesises the pattern nulls which may be completely arbitrary. An example of a 36-element diamond array synthesis is presented.     

Arbitrary footprint patterns from planar arrays with complexexcitations

Elliott and Stern's (1990) method for synthesising shaped patterns using a circular or elliptical planar aperture or array with a complex excitation distribution is generalised to allow the synthesis of footprints of arbitrary shape. The use of complex excitations allows a given footprint to be synthesised using a smaller array than with real excitations. The procedure is illustrated by synthesising a square footprint using an array with a rectangular grid     

Optimum scannable planar arrays with an invariant sidelobe level

This paper presents two alternative methods for determining the current distribution in the elements of a scanning rectangular array which is optimum in the sense that its radiation pattern has a constant sidelobe level and a narrowest beamwidth in all directions. Exact formulas for both even and odd numbers of elements are given. The dependence of the main-lobe beamwidth on the total number of elements, the element spacing, the sidelobe level, and the scan angle is studied in detail. The minimum required number of controlled elements in a square array with electronic beam scanning over a specified sector for a guaranteed upper limit on beamwidth without grating lobes is determined. Numerical results are included, which illustrate many interesting features of the new design technique.     

Infinite planar arrays of arbitrarily bent thin wire radiators

A plane wave expansion moment method is presented for computing active impedances and current distributions of infinite planar arrays of thin wire radiating elements. The array lattices can be rectangular or triangular. The excitations can be plane waves or progressively phased voltage sources. Each radiating element, including feedline, can be any collection of bent thin wires. Results are given for arrays of straight dipoles with straight feedlines, straight dipoles with bent feedlines, and swept back dipoles (arms inclined with respect to the array planes) with straight feedlines. The experimentally observed phenomenon of array blindness as a consequence of feedline scattering is verified theoretically. The absence of this effect when the dipole arms are inclined with respect to the array plane also is verified.     

Optimal power deposition with finite-sized, planar hyperthermiaapplicator arrays

Improved hyperthermia applicator technology is allowing finer spatial power resolution within the heated tissue volume. Effective utilization of these planar applicator arrays requires an understanding of the interrelationships between the lateral dimensions of the tumor and the applicators, the power field produced by the applicators, the amount of surface cooling, the tumor tissue blood perfusion, and the normal tissue blood perfusion. These interrelationships are investigated using three-dimensional power patterns and temperature fields produced by optimizing the power amplitudes of the individual applicators located within an array of small, but finite, planar applicators. Five major conclusions are obtained. First, optimization works and is effective in determining optimal power fields. Second, for optimal treatments the lateral dimensions of a single superficial applicator need to extend beyond the tumor boundary. Third, surface cooling is needed to reduce the high normal tissue temperatures at shallow depths. Fourth, finer power resolution becomes more important as the tumor size decreases, but, little improvement in the temperature field is achieved beyond a 3 x 3 array configuration. Fifth, increasing the normal blood perfusion rate can decrease the temperature on the tumor boundary if direct power deposition on that boundary is unavailable.     

A new quasi-Yagi antenna for planar active antenna arrays

In this paper, a novel broadband planar antenna based on the classic Yagi-Uda dipole antenna is presented, and its usefulness as an array antenna is explored. This “quasi-Yagi” antenna is realized on a high dielectric-constant substrate, and is completely compatible with microstrip circuitry and solid-state devices. This antenna achieves a measured 48% frequency bandwidth for voltage standing-wave ratio <2, better than a 12-dB front-to-back ratio, smaller than -15 dB cross polarization, and 3-5-dBi absolute gain. Mutual coupling of the antenna in an array environment is investigated. Finally, three simple arrays are presented, demonstrating the usefulness of the antenna as an array element. This novel antenna should find wide application in wireless communication systems, power combining, phased arrays, and active arrays, as well as millimeter-wave imaging arrays     

Ultradense silicon nanowire arrays produced via top-down planar technology

A process is developed for the fabrication of vertically arranged poly-silicon nanowires via a rigorously top-down batch process. The technique allows the production of wire arrays with larger linear density (projected on the surface) than those achievable with any of the other proposed top-down processes.     

基于面阵的三维空间信道模型

5G宽带无线系统需要满足极高频谱效率性能需求,全维多输入多输出(Fulldimension Multiple Input Multiple Output,FD-MIMO)传输技术已成为该系统的潜在的物理层技术之一.3GPP 25.996技术规范涉及了二维(Two-Dimensional,2D)双极化空间信道模型(Spatial Channel Model,SCM),它主要考虑了MIMO系统水平维度的方位角度功率谱,未考虑垂直维度的仰角功率谱.基于几何统计的2D SCM模型和极化MIMO信道模型,研究了基站端采用均匀面阵的三维空间信道模型(Three-Dimensional SCM,3D SCM),该信道模型将便于评估FD-MIMO设计的性能.基于计算机模拟,在含有直达径和反射分量的传播环境下,对比了线阵和面阵配置,研究了角度扩展和交叉极化鉴别率对互信息的影响.最后,研究了基站下倾角对小区覆盖的影响.