Parallel-series feed network with improved G/T performance for high-gain microstrip antenna arrays

A 16 x 8 microstrip antenna array with 28 dB of gain at 18 GHz using a parallel-series feed with reduced conductor traces is presented. The feed network connects antenna elements with about 50% reduction in conductor traces compared to conventional arrays with equal numbers of radiating elements. It also enhances the gain-bandwidth performance of the array and maintains a broadside radiation pattern in a wider frequency band. The full-wave simulation results are verified by means of measurements that demonstrate a relative gain-bandwidth of 4.4% with less than 1 dB of gain ripple.     

Optimum design of feed structures for high G/T passive and activeantenna arrays

In this work, noise analysis of parallel feed structures is presented. Signal and noise behavior of the feed structures are signified by the newly introduced concepts of “coherent” and “incoherent” impedance match of power-combining structures. It is also shown that a feed structure can be redesigned for low-noise operation without affecting the radiation characteristics. Optimum design of parallel feed structures for low-noise operation is explained. Also an optimum use of active elements in such structures is investigated to have a low overall noise temperature of the antenna array with minimum number of active elements. In the analysis, a new method is introduced where a “noise-equivalent line length” (NELL) is defined. This definition, which unifies the contribution of noise from different array elements, is used in the design of a parallel feed structure and as an active circuit replacement criteria in passive arrays     

Fast and rigorous calculation method for MoM matrix elements inplanar microstrip structures

An analytical integration technique is proposed for evaluating the elements of the impedance matrix obtained by using the spatial-domain method of moments (MoM) applied to the mixed-potential integral equation (MPIE). This technique is based on a Taylor series expansion of the integrands involving only polynomial functions, and thus allowing immediate analytical Integration     

High-accuracy direction finding in multipath environment with short-wave antenna arrays comprising a small number of elements

A method for short-wave multipath direction finding is considered. The method allows high-accuracy determination of the directions of arrival and the amplitudes of a priori unknown arriving signals through the use of an antenna array comprising a small number of independent receiving elements with narrow-bandwidth filters placed at their inputs. An algorithm based on eigenvector decomposition of the correlation matrix of the complex signals arriving at the inputs of the radiating elements in each subband; separation of the eigenvectors into signal vectors and noise vectors; determination of the receiving-antenna eigenpatterns from the obtained vectors; and substantiation of the functional equation that allows, with the antenna eigenpatterns taken into account, the signals’ amplitudes and angles of arrival of the signals to be determined, is proposed. The results of a numerical simulation, which confirm the high accuracy of direction finding by the proposed method, are presented.     

Design and testing of a feed network for a transparent antenna array

This paper describes the design and testing of a feed network for a transparent flat-plate array antenna. This antenna is the top of a stack of three antennas that must occupy the same volume while pointing in different directions. At many pointing angles, an antenna will create blockage for the antennas underneath. In order to minimize the blockage, the array and its transmission lines must be as transparent as possible to the antennas underneath. The flat-plate array consists of active elements over a frequency-selective surface (FSS) ground plane that is transparent at the frequencies of the antennas below it. The feed lines must also be transparent to the antennas below it. This is achieved by minimizing the total area occupied by the feed lines. Rather than the traditional corporate feed network, a series feed network was designed. Such a network requires that each individual feed point must be fed with a coupler, where the coupling coefficient is adjusted to distribute the same power to each array element. We show the details of the design of the network as well as a set of measurements that show the performance.     

Asymmetric bow-tie antenna for GSM/CDMA and 3G/WLAN

A bow-tie antenna with asymmetrical and overlapped arms printed on the top and bottom of a dielectric substrate is proposed and tested. By adjusting the asymmetry and overlapping of the two arms, return loss below -10 dB, quasi-omnidirectional radiation characteristics, reasonable gain values and beam tilt can be achieved at GSM/CDMA and 3G/WLAN bands.     

S/X/Ka频段天伺馈系统关键技术分析

采用Ka频段进行星地数据传输是解决数据传输频带资源紧张的有效技术途径,将成为星地数据传输的发展方向。针对目前国内外对S/X/Ka地面接收系统缺乏深入的技术研究和工程化产品的问题,分析研究了S/X/Ka天伺馈系统的关键技术,提出了主要技术指标需求及关键技术实现途径。研究结果可为系统的设计、研制加工等提供技术参考。     

5G时代4G/5G共天馈面解决方案

4G建设时期,存在站点天面资源紧缺、无法新增抱杆、物业协调困难等问题,因此,5G时代在现有站点上新增抱杆的需求较难实现,如何实现4G/5G天线共天馈面及快速部署异常紧迫。探讨了4G/5G共天馈面的解决方案,提出一种适合中国电信单抱杆场景网络建设的天馈面解决方案,可以解决5G网络建设中无法新增抱杆、物业协调困难的问题。由于不增加天面资源,可减少铁塔租金,降低网络运营成本,同时可实现5G网络部署简化、便捷、高效。     

Space-time cross-correlation functions for antenna array elements in a noise field

The importance of designing a radar (or communications) receiver to operate effectively in the presence of spatial noise creates the necessity for determining the space-time cross-correlation functions between antenna array elements. A representation of a general, polarized, nonisotropic noise process is used to determine the cross-spectral densities and cross-correlation functions between arbitrarily oriented dipole antenna array elements in the presence of a noise field only. Several examples have been worked out for isotropic noise to show the variation of the cross-correlated noise function vs. the spatial separation of the dipoles. One important result is that the noise cross correlation is shown to be a function of the receiver element spatial orientation when the elements are dipoles. For certain spatial orientations between dipoles it is possible to reduce the noise cross correlation between these antenna array elements to zero.     

兼容4G/WiFi/WiMAX的新型宽带人工电磁媒质天线设计

设计了一款新颖的基于互补开口谐振环结构和条形缝隙的贴片天线。通过在金属贴片上蚀刻圆环形互补开口谐振环结构,并且在金属接地板上蚀刻条形缝隙完成天线的人工电磁媒质结构设计,它们和介质板共同作用将天线工作频段明显扩宽到1.7~2.98 GHz和3.99~5.34 GHz。该天线仅使用单层双面覆铜板即可完成加工,具有结构简单的特点。同时,天线的电尺寸仅有0.408λ0×0.408λ0×0.0086λ0(在天线最低工作频率1.7 GHz处),且最大增益为6.04 dBi;可以同时兼容中国的第四代(4G)移动通信的所有频段(1.88~2.66 GHz)、WiFi频段(2.4~2.484 GHz)和微波存取全球互通(WiMAX)频段(2.5~2.69 GHz)。     

多天线系统的电磁耦合及干扰特性研究

随着移动通信系统的快速更新迭代,使用的频段也越来越丰富,支持全频谱接入通信成为未来基站天线的发展趋势. 而日趋紧张的站址资源对未来基站天线的小型化水平提出了更高的要求. 文章首先介绍了当前多频段基站天线的研究进展和成果,概括了并排式、交错式、堆叠式和嵌套式四种多频段结构类型,着重分析了异频耦合的产生原理和抑制方法;然后总结出共口径技术和异频解耦技术是未来全频谱基站天线的关键技术;最后阐述了当前共口径技术和异频解耦技术存在的局限性,展望了未来全频谱基站天线的研究方向,包括多种共口径方式组合技术、宽带异频解耦技术和大规模共口径天线阵列解耦技术.

     

On design and experiment of the feed cable-suspended structure for super antenna

This paper presents design and experiment of the feed cable-suspended structure for the next generation large spherical radio telescope. To begin with, considering the requirement of the orientation of the feed cable-suspended structure increased to 60° from 40°, optimization design of the structure is performed. Then, aiming at the drawback of weak twisting stiffness of the feed cable-suspended system, a method to add stable cables is proposed to enhance the twisting stiffness of the structure; and a great of experiments had been developed combining with the inner FAST model of 5-m built in Xidian University, which demonstrate the effectiveness and feasibility of the proposed method. Next, the qualitative and quantitative analysis of effect of the stable cables on electronic performance is made. In the end, the results of theoretical analysis, simulation and experiment show that the design project of the feed cable-suspended structure can be applied in large radio telescope with the diameter of 500-m.     

Surface doping using ion implantation for optimum guard layer design in COS/MOS structures

Theory and experimental results using COS/MOS devices are presented for using ion-implanted surface guard layers to replace guard bands in LSI COS/MOS circuits. The function of a guardband is to reduce leakage between neighboring devices; surface guard layers accomplish the same end with the addition of a considerable reduction in the space required for a given COS/MOS memory cell. The price paid for the elimination of the guardbands is a tradeoff between the onset of leakage and the onset of avalanche breakdown between drain and substrate. A systematic method is presented for optimizing these two limiting voltages for a given value of field oxide thickness and for defined limits of the Qsoxide charge.     

An array-compensated spherical reflector antenna for a very large number of scanned beams

There are many stringent demands imposed on the applications of spaceborne antenna systems. One of the most challenging demands is the generation of multiple beams with the ability to scan a very large number of beamwidths. Since the parabolic reflectors have limitations in this application, a 35-m spherical reflector antenna is proposed for a geostationary radar antenna at Ka-band (35.6 GHz) due to its inherent capability of scanning the beams to very large number of beamwidths. The utility of using planar array feeds for correcting spherical phase aberrations is investigated to overcome the performance degradation effects. Two different methodologies are developed for the array excitation coefficients determination based on phase conjugate matching and the results are compared. Using the compensating feed array, the radiation characteristics of the compensated spherical reflector are simulated for no scan and large scan cases and the results are compared with the uncompensated case to show performance improvement. In order to demonstrate the technological readiness of the concept a 1.5-m breadboard model is designed to be built for experimental measurements. Some important mechanical design tolerances and realistic array feed topologies are investigated. The antenna concept developed in this paper is advocated to be used in the next generation of geostationary satellite antenna systems for remote sensing radar applications.     

Design of a wideband Y-shaped antenna for the application in IoT and 5G communication

A small wideband Y-shaped antenna is presented in this paper. A monopole of Y-shaped with two rectangular-shape frequency shifting strip is used to produce a compact dimension of 10 mm × 12 mm on a 1-mm-thick FR4 substrate. The antenna has an impedance bandwidth (measured below ?10 dB from 39.57 to 44.63 GHz), a gain more than 4.9 dB, radiation efficiency of 81%, and voltage standing wave ratio (VSWR) < 2, within the bandwidth of interest, making it a viable option for 5G applications. The use of a (01.7850 × 2.6775 × 00.02) mm³ metallic strip located above the feed line is also shown to efficiently increase the antenna bandwidth to values greater than 5 GHz without affecting the other antenna parameters. Additionally, the measured results in comparison with the simulated results reveal negligible changes, confirming that the proposed antenna is also suitable for the applications of 5G with Internet of Things.     

一种面向5G通信的宽带8单元MIMO天线设计

提出了一种面向5G的宽带8端口多输入多输出（multiple-input multiple-output,MIMO）天线.天线单元采用多枝节单极子结构,能够激发多模态,且能覆盖多频段.同时,采用弯折结构来实现小型化,且在相邻单元之间设计T形突出地结构来提高隔离度.仿真和实测结果显示,该天线在3~7.1 GHz内回波损耗大于10 dB,在3.3~7.1 GHz内隔离度高于15 dB.因为进行了有效的去耦,天线体现出明显的辐射分集特性,天线在目标sub-6 GHz频段内的包络相关系数（envelope correlation coefficient,ECC）接近0.在一8×8 MIMO系统中,计算得到的峰值遍历信道容量为43 bps/Hz,达到传统2×2 MIMO上限值的3.74倍.该8单元MIMO天线具有良好的分集和复用能力,能满足5G通信在sub-6 GHz的高速数据传输需要.     

Numerical analysis of small practical feed elements in a ground plane

A new approach to the numerical analysis of circular-waveguide feed elements in a ground plane is proposed. The feed element may protrude from the ground plane, and a finite wall thickness is taken into account. The method utilises both the method of moments and the geometrical theory of diffraction.     

星载赋形波束单馈源单偏置反射面天线设计

为了使星载赋形波束天线远场方向图与服务区形状匹配良好,并且在波束覆盖区内具有较平坦的方向性系数,将表征反射面形状的Zernike多项式展开系数作为优化变量,建立基于最小P乘法和Minmax方法的适应度函数,利用进化算法进行赋形反射面天线优化。利用该方法设计了覆盖中国大陆和巴西的赋形波束反射面天线。仿真结果表明,天线远场方向图与服务区形状均匹配良好,服务区内的方向性系数波动量分别为2.31 dB和11.23 dB,该值比现有方法小,并且该方法具有较高自由度及收敛性好的特点。     

高通量卫星多波束天线馈电系统PIM控制技术

介绍了无源互调(PIM)产生的机理和控制方法,重点研究了高通量卫星多波束天线馈电系统PIM控制技术,通过采用馈电系统高隔离度优化设计、馈源单元法兰面扼流槽设计、馈源阵安装板PIM源控制设计、Ka频段PIM试验系统低PIM设计等手段,将某Ka频段多波束天线馈电单元的7阶PIM性能控制在高低温(-60~+100 ℃)环境下≤-135 dBm,馈源阵7阶PIM性能控制在常温状态下≤-140 dBm。产品的实际应用验证了所述PIM控制技术的有效性,在工程问题中起到指导作用。