Offset Cassegrain Earth Station Antenna for the Japanese Domestic Satellite Communication System

Offset reflector antennas have advantages for communication systems because they are not severely subject to blocking. Difficulties mainly arising from structual asymmetries have inhibited the realization of an offset reflector antenna with a large aperture for commercial use. This paper describes the design of an offset Cassegrain earth station antenna for the Japanese domestic satellite communication system. Antenna measurements showed 76 and 69 percent aperture efficiencies at 20 and 30 GHz, respectively, less than -20 dBi wide angle directivity and an 18 K noise temperature in operating conditions. Performances are far superior to conventional axisymmetrical earth station antennas. The antenna was reassembled on a telephone office building after the measurements. The antenna gain was reconfirmed there, using the sun as a radio frequency source. Experiments show that the earth station antenna and a terrestrial antenna can be placed on the same building without serious interference.     

Micromachined Loop Antennas on Low Resistivity Silicon Substrates

The integration of K-band (20-40 GHz) full wavelength square wire- and slot-loop antennas on low resistivity (11-70 Omegacm) silicon substrates is addressed. By the use of polymer or silicon oxide/nitride membranes to support the slot or wire loop over micromachined trenches the efficiency of the antennas is enhanced while the majority of the bulk silicon within the aperture of the antenna is preserved to enable the integration of active devices. A 3.6times3.6 mm² large slot loop antenna chip with 200 mum micromachined trench width yields 1.5 dBi gain at 29.5 GHz, while 1.0 dBi gain is obtained at 24 GHz for a wire loop antenna on a 4.5times4.5 mm² large chip with 360 mum wide trenches     

高增益高效率的Fabry-Perot谐振腔天线研究

提出了一种采用非均匀频率选择表面（frequency selective surface, FSS）盖板以及非均匀电磁带隙（electromagnetic band gap, EBG）结构反射地板的高增益Fabry-Perot（F-P）谐振腔天线. 基于漏波理论模型,针对大口径F-P谐振腔天线设计非均匀的FSS盖板和EBG反射地板,控制衰减常数α和相位常数β,改善了口径场上幅度相位分布的均匀性,并抑制了非谐振频率时天线辐射性能的恶化,实现高增益和高口径效率的同时,保证了天线的工作带宽. 所提出的圆形F-P谐振腔天线直径为6.6λ₀,仿真增益为24.6 dBi,口径效率达67.9%,阻抗带宽为4.1%,3 dB增益带宽为3.7%;实测增益为23.9 dBi,口径效率达56.9%. 由于对口径场均匀性的设计,该天线克服了传统F-P谐振腔天线的口径效率和增益间的相互限制.     

Cavity-Backed Miniature Wideband UHF Circular Polarized Antenna With Textured Dielectrics

Use of high permittivity dielectrics with antennas is known to reduce their operating frequency but also introduces side effects such as reduced gain and bandwidth. This paper presents a miniaturization scheme for a 15 cm (6 inch) square circularly polarized (CP), cavity-backed antenna using textured dielectric loading and a folded metallic strip feed. The proposed design has an operational frequency f, around 500 MHz implying a linear size of 0.25lambda₀. The challenge in designing such a small size antenna is to increase bandwidth (10-15%) while retaining a gain of 2-4 dBi. By carefully positioning high permittivity textured dielectrics within the aperture in conjunction with shape design, we show that bandwidth and gain are retained as compared to comparable size antennas in the literature. As part of our design, we present parametric studies through computer simulations and a prototype antenna is fabricated and measured for verification     

基于口面场方法的W波段高口面效率单脉冲卡塞格伦天线

本文提出来一种应用于直升机防撞雷达的高口面效率W波段单脉冲双反射面卡塞格伦天线。口面分析方法的提出解决了W波段反射面天线口面相位分布不均匀的缺陷,从而有效的提高了口面的利用效率。利用该方法,本文研究并制作了口径为135mm、焦距为40.5mm的W波段卡赛格伦天线,并且设计了由四个E面多缝隙电桥和四个四分之一波导波长延迟线级联构成的和差网络。经测试,该单脉冲天线在93GHz具有38.6dBi的和波束增益,相应的口面效率为54.7%;差波束的零深优于-22dB,副瓣电平小于-18dB。测试结果与基于口面分析方法的仿真结果吻合,从而证明了本文所研究天线可以应用于高口面效率的W波段单脉冲系统中。     

一种双模式短波对数周期天线设计

为了适应电离层传播特性,使短波天线更好地与电离层环境匹配,进行大纵深覆盖,设计了一种双模式短波对数周期天线.天线在垂直方向上由两层水平极化对数周期天线构成,通过同相和反相两种激励模式,使得天线能够同时形成低仰角辐射和高仰角辐射.理论仿真和实际测试表明:双模式短波对数周期天线在6～30 MHz频带内,两种模式的电压驻波比...     

The polarization losses of offset paraboloid antennas

In this paper the electric field in the aperture of offset front-fed paraboloid antennas and open Cassegrainian antennas, excited by an electric dipole or Huygens source in the focus, is compared with the fields of front-fed circularly symmetrical paraboloid reflector antennas and classical Cassegrainian antennas. The aperture field forms the basis of expressions to calculate the polarization efficiency of all four types of antenna. Computed results are given, showing that offset antennas can compete with front-fed paraboloids if they are excited by an electric dipole; the classical Cassegrainian antenna, however, shows better results. If offset antennas are excited by a Huygens source, the result is very unfavorable compared with the symmetrical antennas which show no cross polarization.     

Circularly polarized dielectric-loaded planar antenna excited bythe parallel feeding waveguide network

A new receiving planar array antenna for DBS (direct broadcasting satellite) is proposed. The element antenna is a short waveguide aperture mounted in the ground plane, loaded with a dielectric and polarizers, and excited through its side wall by another feeding rectangular waveguide. The gain of the element antenna loaded with a dielectric is so high that the grating lobes can be reduced sufficiently even if the element spacing in the array is wider than the wavelength in free space. Therefore we can reduce the number of the array elements, and parallel feeding by the low loss waveguide network can be feasible to provide a planar array antenna. This paper describes the experimental results of several kinds of the circularly polarized dielectric-loaded element antennas and the planar antennas fed by the waveguide network. In the 12 GHz band the planar antenna with 64-element radiators has a maximum gain of 31.9 dBi with an aperture efficiency of 94.7%, the 1 dB-down frequency bandwidth of the gain is about 800 MHz (6.7% for a center frequency of 11.85 GHz), and the frequency bandwidth of the axial ratio is less than 1 dB of 850 MHz (7.2%)     

低剖面可承载UHF/L双频共口径圆极化定向天线

机/车载多体制通信、测控、探测等多无线系统并存,天线林立,天线间耦合干扰严重,同时与高速机/车薄壁外壳共形的天线还需具有较强承载能力.本文设计了一种适于车壳共形的低剖面可承载双频共口径定向圆极化缝隙天线.天线主体采用开口缝隙的形式来实现天线的小型化和宽带设计,利用微带线来进行耦合馈电.通过在低频天线中心开槽嵌入高频天线...     

Design and Experiment on Differentially-Driven Microstrip Antennas

Design and experiment is given of differentially-driven microstrip antennas. First, the design formulas to determine the patch dimensions and the location of the feed point for single-ended microstrip antennas are examined to design differentially-driven microstrip antennas. It is found that the patch length can still be designed using the formulas for the required resonant frequency but the patch width calculated by the formula usually needs to be widen to ensure the excitation of the fundamental mode using the probe feeds. The condition that links the patch width, the locations of the probe feeds, and the excitation of the fundamental mode is given. Second, the wideband techniques for single-ended microstrip antennas are evaluated for differentially-driven microstrip antennas. A novel H-slot is proposed for differentially-driven microstrip antennas to improve impedance bandwidth. Third, the effects of imperfect differential signal conditions on the performance of differentially-driven microstrip antennas are investigated for the first time. It is found that they only degrade the polarization purity in the -plane with an increased radiation of cross-polarization. Finally, both differentially-driven and single-ended microstrip antennas were fabricated and measured. It is shown that the simulated and measured results are in acceptable agreement. More importantly, it is also shown that the differentially-driven microstrip antenna has wider impedance bandwidth of measured 4.1% and simulated 3.9% and higher gain of measured 4.2 dBi and simulated 3.7 dBi as compared with those of measured 1.9% and simulated 1.3% and gain of measured 1.2 dBi and simulated 1.2 dBi of the single-ended microstrip antenna.     

FDTD analysis and measurement of aperture antennas based on thetriplate transmission-line structure

First, two aperture antennas designated as P-type and C-type antennas are analyzed using the finite-difference time-domain (FDTD) method. Each antenna is made of a triplate transmission line (TTL). A square aperture is cut out of the top plate of the TTL for both antennas to allow radiation. The bottom of the TTL is a planar plate for the P-type antenna and a plate with a hollow cavity for the C-type antenna. The power flow is expressed using Poynting vectors. It is revealed that parallel-plate mode power in the TTL is lower in the C-type antenna, compared with that in the P-type antenna. Second, an array antenna composed of two C-type elements is analyzed. The Poynting vector distribution in the aperture is found to remain almost unchanged when the element spacing is varied. The input impedance of the array antenna converges at an element spacing of approximately 0.9 wavelength. The theoretical radiation patterns are in good agreement with measured data     

一种星载通信混合反射面天线的设计方法

为了使星载通信天线产生1个赋形波束覆盖服务区,同时产生1个固定点波束和1个有限扫描点波束,该文提出一种由2个赋形反射面和3个馈源组成的混合反射面天线。该天线是以赋形主反射面共用为基础,等效为2副单馈源单偏置反射面天线和1副双偏置格里高利型赋形反射面天线,分别产生赋形波束、固定点波束和有限扫描点波束。通过对一副口径为1.2 m的天线各个波束进行仿真实验,赋形波束在Ku收、发频段时波束覆盖区边缘(EoC)方向性系数为27.5 dBi,固定点波束在C收、发频段时天线口径效率高于70%,通过将赋形副反射面及对应馈源横向偏焦实现Ka收、发频段的点波束在服务区内外的扫描。仿真结果表明,该混合反射面天线可实现C/Ku/Ka频段的同时通信任务。     

Ultra Wideband Co-planer Microstrip Patch Antenna for Wireless Applications

In this paper, a comparative study of co-planar gap coupled rectangular and elliptical microstrip patch antenna is presented. It is analyzed by using circuit theory concept. The proposed antennas show ultra wideband operations which depend on dimensions of the patches, gap between them as well as air gap thickness. It is observed that the performance of gap coupled elliptical patch antenna is better than that of rectangular patch antenna while the area of rectangular and elliptical patches is same. The bandwidth of proposed rectangular patch antenna is found to be 50.7 % with average gain of 6.5 dBi while for elliptical patch antenna the bandwidth and gain further improves up to 57.6 % and 9.5 dBi respectively. The theoretical results are in good agreement with the simulated results obtained from IE3D simulation software.     

Ultra-wideband microstrip quasi-horn antenna

The development of a novel ultra-wideband (UWB) antenna is reported. The antenna, based on a microstrip transmission line, forms a quasi-horn and possesses an extremely wide bandwidth of many decades with relatively high gain. It does not require a balun or transition at the input port and is inherently matched. Two such antennas, when used as transmit and receive elements, have a high isolation between them, even when they are placed next to each other and no absorbing material is used. Measured results show a return loss of better than 10 dB from 0.2 to more than 20 GHz, gain from 7.5 dBi at 2.6 GHz to 17.6 dBi at 18 GHz, and good radiation patterns. Although not measured, the antenna should also perform well at much higher frequencies than 18 GHz. With proper size and shape, the antenna can achieve a relatively flat gain response over an extremely wide bandwidth. Calculated and measured radiation patterns also agree reasonably well     

24 GHz On-Chip Antennas and Balun on Bulk Si for Air Transmission

The conditions are investigated under which standard digital bulk Si technology can yield efficient on-chip antennas and baluns for fully differential transmitter and receiver implementations. The effects of the IC material properties and the antenna geometry on radiation and impedance characteristics have been studied. 24 GHz on-chip antennas on lossy Si have been successfully demonstrated, using a standard IC fabrication compatible Cu process. The fabricated antennas demonstrate a gain ranging from 8- to - 10.5 dBi, which is to the best of the author's knowledge, the highest gain reported for antennas in a 10 Omega-cm Si substrate to date.     

79 GHz Slot Antennas Based on Substrate Integrated Waveguides (SIW) in a Flexible Printed Circuit Board

The design, fabrication and characterization of 79 GHz slot antennas based on substrate integrated waveguides (SIW) are presented in this paper. All the prototypes are fabricated in a polyimide flex foil using printed circuit board (PCB) fabrication processes. A novel concept is used to minimize the leakage losses of the SIWs at millimeter wave frequencies. Different losses in the SIWs are analyzed. SIW-based single slot antenna, longitudinal and four-by-four slot array antennas are numerically and experimentally studied. Measurements of the antennas show approximately 4.7%, 5.4% and 10.7% impedance bandwidth (${rm S}_{11}=-10$ dB) with 2.8 dBi, 6.0 dBi and 11.0 dBi maximum antenna gain around 79 GHz, respectively. The measured results are in good agreement with the numerical simulations.      

一种宽1dB增益带宽全介质Fresnel透镜天线

高增益和宽1dB增益带宽天线具有重要意义。文中提出一种E 波段全介质菲涅尔(Fresnel)波带透镜 天线,它包括一个菲涅尔波带透镜以及一个作为馈源的喇叭天线。透镜对电场进行操控,使穿过透镜的电磁波相位变 化满足需求,从而使透镜口径面处的电场分布更加均匀。与传统菲涅尔透镜的焦点电场相比,本透镜在焦点处的电场 值约提高了1. 6~3. 0 V,说明透镜的聚焦特性提高,从而实现更高的增益和带宽。该透镜天线的口径为72 mm,整体剖 面高度仅为52. 47 mm,焦径比为0. 66。透镜采用3D 打印技术进行加工,降低了加工成本。与传统菲涅尔透镜相比,实 测结果表明,该透镜天线在70 GHz 峰值增益达到了27. 5 dBi,1 dB 增益带宽34. 2% (63~89 GHz),占总带宽85. 53%。     

A New Class of Miniature Embedded Inverted-F Antennas (IFAs) for 2.4 GHz WLAN Application

A new class of miniature printed embedded inverted-F antennas are proposed for operation in the 2.4–2.485 GHz wireless local-area network band. One of the proposed antennas on FR4 substrate (dielectric constant = 4.4) measures 9.2 mm by 4.1 mm and has a bandwidth of 3.5%. The peak gain of this antenna is 1.4 dBi. An overall size reduction of 70% is achieved compared to a conventional inverted-F antenna. Effects of dielectric loss tangent and material conductivity on the bandwidth and efficiency of these antennas are also investigated. Finally, two embedded antenna elements are analyzed to demonstrate the feasibility for a decoupled antenna pair consisting of switched and combining diversity schemes.     

超介质覆层在偶极子天线上的应用

以研究超介质覆层对天线为目的,基于超介质理论中细导线阵列尺寸与等离子体工作频率关系的数学模型,将一个理想偶极子嵌入到周期性细导线圆阵列构成的超介质覆层中,设计了一种超介质覆层加载的高增益全向天线。该天线辐射特性的仿真结果表明,在1.57~1.65 GHz频段范围内,理想偶极子的增益从2.4 dBi提高到7.7 dBi,并呈现出高收敛性及全向性。所采用的数学模型计算出的理论结果与该天线的仿真结果基本吻合,验证了将该数学模型应用于天线设计的正确性,利于缩短天线开发周期,并对分析细导线阵列的负介电常数、负折射率的产生机理具有一定指导意义,对设计性能更完善的超介质覆层加载的天线提供了理论依据。     

一种正六边形嵌套分形超宽带天线的设计

针对当前超宽带天线存在的方向性差、增益小的现状,提出了一种正六边形嵌套分形的超宽带天线。天线利用嵌套分形结构的自相似性和空间填充特性,有效拓展带宽,缩减天线尺寸。通过对天线维数进行仿真分析,选择带宽满足超宽带指标的四维和五维天线;对四维天线和五维天线的E-H面方向图及增益进行对比得知,五维天线较高增益由方向图畸变产生,故选择方向性更好的四维天线为此次设计的目标天线。目标天线尺寸仅为20 mm×23 mm×1.6 mm,带宽为2.7~10.6 GHz,增益为1.8~7.8 dBi,且天线实现了良好阻抗匹配。与引文其它天线相比,目标天线具有较小的尺寸,同时具有良好的方向性和较高的增益。天线实测结果与仿真基本吻合,验证了其研究与应用价值。