A Dual-Mode Millimeter-Wave Folded Microstrip Reflectarray Antenna

A dual-mode folded microstrip reflectarray antenna was developed and demonstrated in this paper. The proposed folded reflectarray antenna contains three parts: a planar main reflector, a planar subreflector, and printed feed antennas. The main reflector is used to produce twisted reradiated fields and to provide phase compensation for focusing. The subreflector parallel with the main reflector is made of a substrate printed with high-density metal grid lines, which is transparent to perpendicularly polarized fields, but would reflect the parallel ones. Three fixed-position patch antennas with polarization parallel to the grid lines are created for the radar mode, so that the radiation beam is switchable. Another patch with perpendicular polarization is designed for communication. A simple approach was proposed for simulating and designing the folded reflectarray. Measured results show good agreement with the calculated ones.     

新型定向超宽带天线

基于圆片单极天线是一种结构简单的超宽带天线,研究了一种新型的超宽带天线,它将4个圆片单极天线垂直交叉放置作为馈源并采用平板反射面,实现定向以及双极化或圆极化特性。分析了2种变形形式:将平板反射器换为抛物面反射器,实现高增益特性;将圆片振子变形,实现更宽的低频端阻抗带宽。通过电磁仿真软件,计算了天线的S参量和辐射方向图随频率的变化规律。分析表明文中的天线对于传统的圆片单极天线有了有效的改进,实现了超宽带、定向辐射、双极化、圆极化、高增益等不同的特性,它们在卫星通信和移动通信中具有良好的应用前景。     

Depolarization properties of offset reflector antennas

The cross polarized radiation for linearly polarized excitation and the beam displacement for circularly polarized excitation have been investigated for offset reflector antennas. Numerical calculations are given to illustrate the dependence upon the angletheta_{0}between the feed axis and the reflector axis as well as upon the half-angletheta_{c}subtended at the focus by the reflector. In the casetheta_{0} = theta_{c} = 45deg, measured results have been obtained for both linearly and circularly polarized excitations with a dual mode feed illuminating an offset paraboloid. The cross polarized radiation of horn reflector and open Cassegrainian antennas rises sharply to rather high values off the beam axis; however, in general, the maximum cross polarized radiation of offset reflector antennas can be made small by using a small angle between the feed and reflector axes. The cross polarization caused by offset is compared with that caused by an unbalanced feed pattern. The effect of the longitudinal current distribution and of departure of the surface from a paraboloid on cross polarization are also examined. The clarification of these cross polarization properties is found to be valuable in the design of reflector antennas.     

双频基站天线中的反射板形状设计

蜂窝移动通信系统中的基站天线通常由直线阵列加反射板构成,而反射板的形状主要影响天线的前后比特性及水平面辐射方向图.该文对适合于基站天线的几种典型反射板形状进行优选,并采用矩量法线栅技术仿真计算了各种反射板形状对天线辐射性能的影响,根据仿真结果给出了满足基站天线双频辐射要求的反射板形状.     

一款面向5G微基站的双频双极化电磁偶极子天线的设计与分析

小型化是进行5G微基站天线设计的重要考虑因素,文中设计了一款适用于5G微基站的电磁偶极子天线. 天线由一对正交放置的单极化电磁偶极子、一对交叉放置的渐变式Γ形馈电线、一个圆形寄生贴片和一块正方形反射板组成,工作频段为2.50~3.62 GHz和4.8~5.0 GHz,能够覆盖工信部规定的5G的全部中频段. 在工作频带内,天线的输入回波损耗小于?10 dB;端口隔离度在低频段小于?25 dB,在高频段小于?42 dB;仿真平均增益在高、低频部分分别为5.57 dBi和9.84 dBi. 该天线能够实现双频段和双极化,可以作为小型化微基站天线设计的参考,同时为5G天线的商用化提供参考.     

多模反射面天线理论与技术研究

在卫星星座跟踪、远距离微波能传输等需要构建大功率均匀场的领域,都需要具有平顶波束的高增益反射面天线.受多模和混合模喇叭天线的启发,文中创新性地在反射面天线设计中引入了多模的理念.首先提出了双模反射面的思路,即在标准抛物面天线的最大辐射方向上引入相位差为180°的反相模式场,由两种模式合成平顶波束.然后,将双模的理念推广...     

L/S双频段圆形阵列单脉冲抛物面天线

该文研究了一种以六单元圆形阵列作为照射器的单脉冲抛物面天线,这种天线具有实现宽频带跟踪的独特优点,其输出信号类似于圆波导单口径多模馈源,具有一个和波束,一个锥形差波束,并给出了没有接收机参与的情况下,将宽频带的和差两个通道变成单通道的途径。研制了一套L(1#61485;2GHz),S(2.2#61485;2.3GHz)宽频带双圆极化单通道单脉冲天线,对该天线的照射器、分波器、波束形成网络、单通道变换器等组件和馈源结构集成化设计进行比较详细的介绍。该馈源安装到一个3.2m的抛物面上,频率为1.1GHz,2.2GHz时,和波束增益分别为22.9dB,30.1dB;差波束零深为35dB,40dB。在L/S两个频段内跟踪稳定。     

宽带极化与方向图可重构天线研究

随着无线通信系统的快速发展, 宽带可重构天线将在未来发挥巨大作用.文中综述了四种宽带极化与方向图可重构天线, 它们都具有提高通信系统容量, 消除极化失配, 扩大辐射范围等特点.首先介绍了一种宽带的多线极化可重构天线.此款天线基于L型探针馈电的贴片天线, 实现了0°, 45°, 90°以及—45°极化的选择, 具有宽带、低剖面、高增益的特点.其次, 同样基于L型探针馈电的贴片天线, 通过引入一个输出相位可重构的功分馈电网络, 实现了宽带的圆极化可重构天线, 其同样具有宽带、低剖面、高增益的特点.除了极化可重构天线, 文中还介绍了两款方向图可重构天线, 可分别实现线极化以及圆极化的全向锥状波束以及定向辐射波束的方向图可重构.前者是基于宽带的单极子贴片天线跟L型探针馈电的贴片天线的有机结合.后者是基于环缝隙的贴片天线配合激励端口可重构的功分馈电网络的组合.此两款天线均具有结构紧凑、宽带、增益稳定的特点.     

Dielectric reflector backed aperture-coupled antennas for reduced back radiation

A new design using a dielectric reflector to reduce the back radiation of aperture coupled antennas is proposed and developed in this paper. To validate the proposed design, a concise theory analysis is first conducted and then the proposed design is analyzed in a modified aperture coupled microstrip antenna. In this design, a radiating patch and a microstrip feed line are both etched on the same side of a top substrate and a coupled slot is etched on the opposite side of this substrate. To examine the effect of the dielectric reflector on the antenna performance, theoretical simulations and experimental investigations were carried out, and a good agreement between the theoretical expectation and the measured results validates the proposed design. The measured radiation patterns show that the proposed structure can offer a high radiation efficiency, a high front to back radiation ratio, and a high co-cross polarization ratio. With these features, the proposed design is significant in the electromagnetic interference and electromagnetic compatibility (EMI/EMC) designs for reduced undesirable radiation.     

Printed millimeter-wave reflectarrays

Periodic and quasi-periodic structures printed on a dielectric substrate can be employed to control reflection and transmission properties of incident waves as a function of structure geometry. This can be done mostly independently for both polarizations. These structures thus allow the realization of different kinds of filters and polarizers. Local variation of the element geometry on a substrate with backside metallization — resulting in respective variations of the reflection phase angle — can be employed to design printed reflectarray antennas. Including the dual polarization properties of such antennas, dual function or dual frequency antennas can be built, or these properties can be exploited for the realization of compact, low-profile folded reflector antennas. Examples for a number of antennas are presented, including dual radiation characteristics, dual frequency operation, and very compact, low loss folded reflector antennas     

非赋形双偏置高性能椭圆波束天线

分析了非赋形双偏置天线产生椭圆波束的机理,将馈源的椭圆波束照射到轮廓线为椭圆形的付反射面上,通过双偏置天线的对称转换原理,主反射面产生椭圆波束.馈源波束由矩形口径的多模喇叭产生,它提供了等化的方向图.给出了馈源及天线的方向图计算公式.实验结果表明,实测方向图基本与理论计算一致.与其他类型的椭圆波束天线相比,本天线加工简单,同时天线效率也较高.     

Mesh antennas for dual polarization

Three mesh antennas, all having an extremely small antenna height of approximately 0.06 wavelength above a ground plane, are presented. First, a mesh antenna excited with a balanced feed is analyzed. It is revealed that the mesh antenna radiates a linearly polarized wave with no cross-polarization component in the principal planes. The radiation mechanism is explained using the current distribution. Second, a mesh antenna excited with an unbalanced feed is analyzed. This antenna shows almost the same radiation characteristics as the mesh antenna with a balanced feed. The frequency bandwidth for a VSWR=2 criterion is evaluated to be approximately 3%. Third, a mesh antenna having two perturbation elements is analyzed. It is found that the antenna acts as a radiation element of circular polarization. The frequency bandwidth for a 3-dB axial ratio criterion is calculated to be approximately 1%. The mesh antennas in the first and second analyses can be used as dual linear polarization elements by appropriately switching the feed. Similarly, the mesh antenna in the third analysis can be used as a dual circular polarization element by switching the feed     

Optimizing multimode horn feed arrays for offset reflector antennasusing a constrained minimization algorithm to reduce cross polarization

This letter presents an algorithm for suppressing the cross polarization of single offset reflector antennas illuminated by a cluster of multimode horn feeds using a constrained minimization routine. The design variables are the mode ratios for the higher order modes excited in the feeds relative to the dominant TE₁₁ mode. The goal is to systematically determine the optimum mode ratios such that the overall crosspole performance of the reflector antenna improves relative to the single TE₁₁ mode excitation. The multimode horns considered are Potter-type (dual mode) horns and trimode horns     

机械调整式极化跟踪器

在低剖面动中通天线系统中,辐射器多为平板阵列或柱形抛物面的形式,由于天线高度限制,无法通过旋转天线面板的方式进行极化跟踪,需要独立的极化跟踪调整机构,针对此提出了一种新型机械调整式极化跟踪器,具有结构紧凑和可靠性高的特点。通过电机驱动波导关节及OMT实现上行极化调整。基于极化波合成的工作原理,提出了系统设计方案,并描述了核心器件的设计方法。给出仿真与实测结果,且二者吻合较好。     

Application of rectangular and elliptical dielcore feed horns toelliptical reflector antennas

The pattern characteristics of elliptical reflector antennas are investigated when they are fed by rectangular and elliptical horns partially filled with a dielectric. The bandwidth characteristics of these dielcore horns are superior to those of their corrugated horn counterparts. Representative reflector patterns are computed to properly demonstrate the utility of these feeds for reflector antennas with elliptical apertures. This reflector antenna exhibits high efficiency and low cross polarization, and may be suitable for radar and satellite antenna applications. The antenna configuration may become useful in relatively small antennas where more than 10% cross-polar bandwidth is required. The efficient dielcore horns may also be used as feeds for elliptical nonshaped dual-reflector antennas     

Single-feed slotted equilateral-triangular microstrip antenna forcircular polarization

Novel designs of single-feed equilateral-triangular microstrip antennas for circular polarization (CP) are proposed and studied experimentally. It is demonstrated that by embedding a narrow slot or a cross slot of unequal slot lengths in the triangular patch, circularly polarized radiation of microstrip antennas can easily be achieved using a single probe feed. Furthermore, results show that for the design with a cross slot, the proposed antenna can perform CP radiation with a reduced antenna size at a given frequency (denoted as compact CP operation here); that is, the required antenna size is smaller for the proposed antenna for performing CP radiation as compared to a conventional circularly polarized triangular microstrip antenna at a fixed operating frequency. Details of the proposed CP designs are described, and typical experimental results are presented and discussed     

Edge-fed patch antennas with reduced spurious radiation

In this paper, a technique to reduce the spurious feed radiation from edge-fed patch antennas by using a dual thickness substrate is presented. A thin microwave substrate is employed for the feed network, and then a transition is made to a thick substrate for the patch antenna element. The new feeding procedure allows the feed network and antenna elements to be optimized independently. Measured results on a single element prototype exhibit a reduction in the level of cross-polarized fields and decreased pattern distortion whilst preserving a reasonable impedance bandwidth. The technique is also proven to be beneficial in an array environment, as an extensive transmission line feed network is required. We present the theoretical and experimental results of a 1 /spl times/ 8 edge-fed patch array that utilizes the dual thickness substrate configuration. Significant improvement in the radiation patterns and gain are observed for the new array compared to a standard edge-fed patch array.     

Étude en optique physique d’une antenne a double réflecteur

After having recalled to mind some fundamentals of the electromagnetic theory, the authors compare experimental and theoretical results obtained in the approximation of physical optics for a few known antennas. For the Cassegrain antenna, the surfaces of the main reflector and of the auxiliary reflector and the incident field generated by the primary source, constitute data. First, the distribution of the field on the auxiliary reflector is determined. After that, the radiation in the area near the auxiliary reflector with regard to the main reflector, is calculated, and then the electromagnetic field radiated at a great distance by the antenna. The calculation programme is a general one, and applies to reflectors of any shape. Results obtained on two Cassegrain antennas belonging to the CNET are presented, one of them being of the revolution type and the other of the asymmetrical dual reflector type.     

Analysis of circularly polarized square ring and crossed-strip microstrip antennas

Segmentation technique coupled with cavity model have been used to analyze square ring and crossed-strip microstrip patch antennas for circular polarization. This technique is found to predict the characteristics of antennas correctly, as is evident from the close agreement between the calculated and measured results for resonant frequency, input impedance, radiation patterns, and bandwidth. Square ring antenna has been found to have larger impedance bandwidth and axial ratio bandwidth because of lowerQ. Crossed-strip antenna has larger size and thus fabrication tolerances can be relaxed.     

一种多功能反射面天线的设计

介绍了一种多功能反射面天线的设计方法,利用同一反射面实现跟踪和干扰的功能。跟踪采用副面为栅条形式的卡塞格伦天线,干扰采用前馈抛物面天线。2种天线正交极化,通过理论计算、仿真优化结合合理的结构设计,保证2种天线的电性能及相互之间的隔离度。