Pattern synthesis of the offset reflector antenna system with lesscomplicated phased array feed

The performance degradation of an offset reflector antenna with off-axis scanning feed and distorted reflector surface can be improved by using a phased array feed. Generally, both analog attenuators and phase shifters are used in phased array feed. Yet, it seems to make the feed system very complicated. In this paper, a phase-only gradient search (POGS) algorithm is developed to optimize the performance of offset reflector antenna systems using phased array feed that is equipped with phase shifters only. This technique not only can greatly simplify the complexity of phased array feed, but also can provide the reflector antenna with better antenna gain and sidelobe level control capability. Simulation and experimental results are presented to illustrate the excellent performance of offset reflector, with limited beam scanning capability, can be obtained by using this less complicated phased array feed     

Leaky-Wave Slot Array Antenna Fed by a Dual Reflector System

A leaky-wave slot array antenna fed by a dual offset Gregorian reflector system is realized by pins in a parallel plate waveguide. The radiating part of the antenna is composed by parallel slots etched on one side of the same parallel plate waveguide. The dual offset Gregorian reflector system is fed by an arrangement constituted by two vias and a grid, also constituted by pins. Also this feed arrangement realizes a leaky type of radiation, this time inside the parallel plate waveguide. A prototype of the antenna has been designed, manufactured and successfully tested. The low profile, low cost and high efficiency of the antenna render it suited for a variety of radar or telecom applications.     

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.     

Beam squint in a linearly polarised offset reflector antenna

A beam squint has been found to occur in the field radiated by an offset paraboloid antenna illuminated by a feed with linear polarisation in the plane of offset. The squint, whose existence has been confirmed by computed and measured radiation patterns, occurs in the offset plane, and is typically 0.03 of a beamwidth for a reflector of 6-wavelengths diameter. An assessment is given of the likely effect of the squint on the performance of an offset reflector radiating a circularly polarised field     

Simplified linearly polarised contoured beam reflector antenna for a European coverage requirement

The design of a linearly polarised contoured beam reflector antenna for a European coverage requirement is described. The antenna is a 1.1 m offset reflector, fed by an array of only five rectangular feed horns, operating in a 10.7?11.7 GHz band. The minimum gain requirement of 28 dBi for the contoured beam, in contrast to the current ECS-1 CEPT (Conference Europeenne de Poste et Telecommunication) elliptical Eurobeam gain requirement of 25 dBi, is achieved.     

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。     

A compact Q-K-band dual frequency feed horn

A millimeter-wave dual frequency circularly polarized feed for an offset reflector antenna is being developed for a portable satellite ground terminal. The two frequency bands areQ- andK-bands for transmit and receive, respectively. A compact feed design consisting of a single corrugated horn with two circular waveguide concentric openings at the horn throat is described. Good aperture efficiency and low sidelobes in both of the frequency bands are achieved.     

A high aperture efficiency, wide-angle scanning offset reflectorantenna

A unique single offset reflector antenna has been designed which provides as much as ±30° of scanning in azimuth while maintaining a much higher aperture efficiency than a torus antenna. Like a torus antenna, different portions of the reflector are illuminated for each scanned beam. The reflector profile curve in the plane of scan is found by least squares to minimize the error for the beams with the greatest scan angle, and then polynomial terms of up to sixth order which minimize nonplanar phase errors are added to produce a three-dimensional reflector surface. Numerical simulation indicates very good results for all 0.5° beams in the ±30° azimuth field of view, with peak gain no more than 0.3 dB below ideal and highest side-lobe levels no worse than 13.3 dB below the peak gain. Additionally, comparable performance can be extended to the elevation plane out to 15°/-30°, although full azimuth performance becomes compromised at extreme elevation scan angles. By using an offset design, there is no blockage of the outgoing beam by the feed array assembly for azimuth scanning. With better feed performance than comparably sized paraboloids, and being more compact than similar torus reflectors, this novel antenna should find numerous uses in spacecraft and terrestrial applications     

Antennes embarquées à réflecteurs multisources

Three telecommunication satellite antennas, developed under the research and development programme of the European Space Agency, ESA, are described. The first one, operating around 1.6 GHz, is to equip advanced mobile communications satellites. It includes an 8 m unfurlable reflector and a system of multiple feeds. The influence of facets in the mesh reflector surface on the radiation patterns is discussed. The second one, for European coverage in the 10.7 to 11.7 GHz band, includes a 1.1 m offset reflector fed by 23 horns backed by a numerically machined waveguide distribution network. Performances of the antenna, with emphasis on the distribution network, are discussed. The third antenna, operating at 19 GHz, generates 0.25° low sidelobe spot beams to cover major European traffic centers. Its 4 m offset Cassegrain reflector is fed by a system of about a hundred horns. Each beam originates from a cluster of seven horns, some clusters, corresponding to closely adjacent beams, partially overlap. The design and performances of the antenna and its components are discussed in the paper.     

一种Ku波段帽型组合馈源设计分析

针对船载小口径天线的馈源设计需求,对一种新型组合馈源的馈电结构进行了模式分析,给出了一个环形口面辐射场的计算方法。通过优化提出了一个Ku频段线极化工作的组合馈源设计实例。经过CST优化仿真,组合馈源的反射板不到3个波长,且在馈源辐射波束半张角为90°时,主面边缘照射电平约为-10 dB。同时由于该组合馈源具有自支撑结构优点,因此非常适合应用于小口径、小焦径比的反射面天线。     

Comparison of the design of a contoured-beam and an elliptical-beamsatellite offset reflector antennas to cover the Taiwan island regionfor satellite communications

For the design of the satellite antenna for the future geostationary (GEO) satellite communication or DBS (direct broadcasting satellite) applications to serve the Taiwan Island region, it may be required to have a antenna beam which effectively covers the Taiwan region and reduces the antenna radiation level in the nearby area of mainland China. Two cases of the Ka-band (20 GHz) satellite antenna, a shaped offset reflector antenna to synthesize a contoured beam and an elliptical offset reflector antenna to generate an elliptical beam, have been studied. This paper presents the comparison and discussion of the antenna coverage performance of the two designs     

A Novel Beam Squint Compensation Technique for Circularly Polarized Conic-Section Reflector Antennas

Beam squint generally exists in offset reflector antennas with circularly polarized feeds. It is manifested by a small beam shift of the radiation pattern in the plane perpendicular to the principal offset plane, which can significantly affect the beam pointing accuracy. In this paper a practical and widely applicable compensation technique for the beam squint is proposed. Simulation results show that a small lateral feed displacement in the perpendicular plane can effectively minimize or eliminate the linear phase shift caused by the depolarization effect, thus compensating for the beam squint effect. This is in practice very useful for offset reflector antennas where the previously suggested method based on feed tilting may not be proper. A simple formula is derived to quickly estimate the optimal feed displacement for both right- and left-hand circularly polarized feeds. Three representative examples: a single offset parabolic reflector, a suboptimal offset Cassegrain reflector, and an axially symmetric Cassegrain reflector with an off-focus feed, are presented to validate the proposed method. Satisfactory results are achieved for all three examples.      

W 波段CW 雷达TR 高增益低副瓣天线

本文设计了W 波段CW 雷达TR 高增益低副瓣天线,该天线采用偏馈切割反射面,天线尺寸带到400 个 波长,实现了高增益、低旁瓣、扇形波束,从而避开馈源及其支杆的遮挡,消除了由于遮挡造成的旁瓣电平上升, 又改善了馈源的输入电压驻波比;为了测试出准确的天线参数,研制了用于该天线使用和测量的高角度分辨率的天 线转台、角度精密指示器、天线转台控制器和测试数据采集系统。解决了窄波束（0.2°）高增益天线远场测试问题, 得到了较好的天线实测结果,满足了总体对天线设计的要求。     

Development of a 45 GHz multiple-beam antenna for militarysatellite communications

Design and experimental results of a wide-angle coverage 45 GHz multiple-beam antenna for military satellite communications are presented in this paper. The high-gain spot beams with low sidelobe levels and efficient adjacent beam overlap are generated by employing an offset parabolic reflector with overlapping feed clusters. The beam shape can be adapted to cancel either single- or multiple-jammers by varying excitations within the feed cluster corresponding to the beam. Development of antenna components including Potter horn, polarizer, phase-amplitude controller, and beamforming network is discussed. Measured results of the demonstration antenna have shown that sidelobe and crosspolar levels of better than -25 dB are achieved for beams scanned over an eight-degree diameter circular coverage region. The adapted patterns of the antenna agree well with the computations, and null depths of better than 30 dB have been realized over a 4.5% bandwidth     

Characterization of tapered slot antenna feeds and feed arrays

A class of feed antennas and feed antenna arrays used in the focal plane of paraboloid reflectors and exhibiting higher than normal levels of cross-polarized radiation in the diagonal planes is addressed. A model which allows prediction of element gain and aperture efficiency of the feed/reflector system is presented. The predictions are in good agreement with experimental results. Tapered slot antenna (TSA) elements are used as an example of an element of this type. It is shown that TSA arrays used in multibeam systems with small beam spacings are competitive in terms of aperture efficiency with other, more standard types of arrays incorporating waveguide type elements     

用FDTD和物理光学混合法分析毫米波抛物面天线

抛物面天线通常的分析方法是几何光学法和物理光学法,对于电大尺寸的抛物面天线这两种方法都可以得到较好的结果,对于电小尺寸馈源的抛物面天线,馈源方向图不仅取决于辐射器本身的辐射特性,其馈电结构对馈源方向图也有较大的影响,在此情况下,用上述方法得到的结果与实验结果之间有较大的误差.利用FDTD可以把整个馈电结构纳入计算域中,得到辐射器完整的近区场,由等效原理可求出抛物面上电流分布,从而用物理光学方法计算抛物面天线远区场.本文用这种混合方法分析计算了毫米波波导裂缝作为辐射器的抛物面天线,计算结果和测试结果相当吻合,证明了方法的有效性.     

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。     

Scanning properties of large dual-shaped offset and symmetricreflector antennas

The scanning properties of shaped reflectors, both offset and circularly symmetric, are examined and compared to conic section scanning characteristics. Scanning of the pencil beam is obtained by lateral and axial translation of a single point source feed. The feed is kept pointed toward the center of the subreflector. The effects of power spillover and aperture phase error as a function beam scanning are examined for several different types of large reflector design including dual-offset, circularly symmetric large f/D, and smaller f/D dual reflector antenna system. It is shown that the Abbe-sine condition for improved scanning of an optical system cannot, inherently, be satisfied in a dual-shaped reflector system that is shaped for high gain and low feed spillover. The gain loss, with scanning, of a high-gain shaped reflector pair is demonstrated to be due to both aperture phase error loss and power spillover loss     

The dielectric-filled parabola: a new millimeter/submillimeterwavelength receiver/transmitter front end

A design is presented for a semi-integrated millimeter/submillimeter wavelength receiver/transmitter front end incorporating a planar antenna and a solid-state device in an efficient feed structure which can be matched directly to high f-number optical systems. The feed system combines the simplicity and robustness of a dielectric substrate lens with the high gain of a parabolic reflector in a single structure that is termed a dielectric-filled parabola. The same fundamental unit can be configured as either a heterodyne or direct detection mode receiver, a power transmitter or a frequency multiplier by changing out the solid-state device and/or the integrated antenna. The structure can also be used with a small integrated antenna array in a multibeam or imaging arrangement. Design and fabrication details for the feed system are given. These are followed by beam pattern and impedance measurements taken on a microwave model when dipole, bow-tie, log-periodic, and log-spiral antennas are used as the integrated feed elements     

A method for producing a shaped contour radiation pattern using asingle shaped reflector and a single feed

Eliminating the corporate feed network in shaped contour beam antennas will reduce the expense, weight, and RF loss of the antenna system. One way of producing a shaped contour beam without using a feed network is to use a single shaped reflector with a single feed element. For a prescribed contour beam and feed, an optimization method for designing the reflector shape is given. As a design example, a shaped reflector is designed to produce a continental-United-States (CONUS) coverage beam. The RF performance of the shaped reflector is then verified by physical optics