Compact high-gain composite horn antenna for space-borne beacon application

ABSTRACT

The growing interest in higher capacity communications satellite necessitates the development of compact and lightweight other antennas (such as beacon horn antenna) at Earth-viewing deck due to crowded accommodation and weight limitation. In this article, we describe an innovative and compact high-gain composite horn antenna for space-borne beacon application. We have designed, manufactured and measured beacon horn antenna operating from 10.7 GHz to 12.5 GHz. The beacon horn antenna is devised by combining stepped section at input, axial corrugated in mid and finally radial corrugated sections. This engineered multiple sections provide extra flexibility of optimisation, leading to high edge of coverage (EoC) gain for Indian mainland, Lakshadweep Islands and Andaman & Nicobar Islands. The radial corrugated section is specially profiled using multi-profile subsections. The mode-matching technique (MMT)-based software CHAMP and ‘minimax optimiser’ have been used to analyse and optimise the Beacon horn antenna. Manufacturing of the horn using a turning machine over aluminium alloy helps to reduce its cost. Characterisation of the beacon antenna confirm predicted electrical results (return loss> 17 dB, cross-polarisation discrimination < ?40 dB, EoC gain > 24 dB). The Accommodation of the Ku-Beacon antenna on spacecraft is discussed with help of its near field from the scattering point of view and its tilt.     

具有L波段单脉冲跟踪能力的L/S双波段共用波纹喇叭天线

单脉冲跟踪以其精度高、速度快等优点而被广泛应用于跟踪中、低轨卫星通信天线中.本文工作研究单槽深波纹喇叭的差模临界截止点和电压波腹点,通过提取波纹槽差模信号,设计了具备L频段单脉冲跟踪能力的L/S双频共用喇叭天线.实际测试结果表明,在L/S频段该喇叭具有良好阻抗匹配特性和辐射方向图旋转对称特性,且L频段差模信号实现了单脉冲跟踪能力,该喇叭天线电气性能满足工程应用要求.     

The corrugated horn as an antenna range standard

The corrugated horn discussed here is a valuable tool for use in microwave pattern ranges. It has the properties of concentrated energy in the main beam, low backlobes, high efficiency and almost monotonic amplitude, and phase radiation patterns which make the corrugated horn useful for a source antenna in a pattern range and also as a possible standard antenna for calibration purposes. A sample of the references that have dealt with the corrugated horn is given for the benefit of the reader [1]-[7].     

一种Ka/EHF双频段波纹喇叭

介绍了卫星和地面站天线越来越需要高性能的双频段波纹喇叭馈源,给出了额Ka/EHF双频段波纹喇叭的结构组成,详细地给出了该波纹喇叭各段的设计公式和波纹喇叭槽参数,利用Champ仿真软件仿真计算了该波纹喇叭2个频段的反射损耗和归一化辐射功率方向图,并且在微波暗室测出了该波纹喇叭反射损耗和归一化辐射功率方向图。测试结果和仿真计算结果吻合良好,因此,证实了该波纹喇叭设计的正确性。     

A dielectric hybrid mode antenna feed: A simple alternative to the corrugated horn

A hybrid-mode horn antenna has been analyzed theoretically and experimentally. It consists of a conical metal horn with a dielectric core inside, separated from the metal wall by another dielectric layer with lower permittivity than for the core material. It is characterized by a very simple design and excellent electrical performance. The horn can support the balanced hybrid HE11-mode, and exhibits low cross polarization and low sidelobes over a wide frequency range. Compared to corrugated horns, the new horn has a simpler design, is easier to analyze, and has the potential of similar cross-polar bandwidth as for corrugated horns with ring-loaded corrugations. Drawbacks are the effects of dielectric losses. Thus the new horn represents an attractive alternative to the corrugated horn antenna.     

A horn-reflector antenna for high-performance submillimetre-wave imaging arrays

We have developed an antenna for high-performance submillimetrewave imaging arrays. The antenna comprises a corrugated horn with an off-axis paraboloidal reflector at its aperture. The corrugated horn is machined directly into two halves of a split aluminium block. This approach avoids electroforming and is compatible with E-plane circuit technology. The resulting antenna is light weight and is ideal for space applications. For compatibility with submillimetre-wave optics, the the behaviour has been calculated by using Gaussian-Hermite modes, and the integrity of the theory has been verified by modelling the behaviour of a 17GHz antenna. The manufacturing procedure has been investigated by machining and testing a horn-reflector antenna for 450–500GHz. Our next step is to extend the technique to 1THz.     

基于螺纹槽结构的90°波纹喇叭性能研究

为了拓宽宽带通信天线波纹喇叭馈源的工作频带，设计了一款新型90°波纹喇叭，它的波纹槽以阿基米德螺线的轮廓向外扩展. 仿真和测试结果表明:该新型波纹喇叭最优工作带宽可达2∶1，在10~20 GHz的工作频带内，具有稳定的相位中心，其45°面最大交叉极化电平低于?25 dB；在宽频带内波束宽度保持相对恒定，且天线E面和H面辐射方向图的?10 dB波束宽度非常接近. 该新型波纹槽可以在宽频带内使得喇叭的辐射方向图更为对称，是改善波纹喇叭性能的新思路.     

一种超宽带多模喇叭的设计

采用模式匹配法结合优化算法，为新疆天文台110 m天线研制出一种工作频带为4~12 GHz的三倍频多模喇叭.该喇叭由225个圆波导台阶组成，除了加工制造易于实现之外，与常规多模喇叭以及波纹喇叭相比，最突出的优点是在超宽频带内具有等化的辐射方向图，非常适合用作超宽频带射电天文观测天线的高效率馈源或者用于其他需要超宽频带设计的天线.     

Design of wide-band compact corrugated horns

It is shown that a specially profiled corrugated horn with a ring-loaded input converter section is capable of operating over bandwidth ratios of up to 2.4: 1. The cross polarization across the band is relatively low, and the change in beamwidth and phase-center position with frequency is acceptable for many applications. This "compact" horn is significantly smaller than the conventional wide-band corrugated horn, and is particularly recommended as a feed in a dual-reflector antenna where space is limited.     

Broadbanding of corrugated conical horns by means of the ring-loaded corrugated waveguide structure

Broadbanding of corrugated conical horns is investigated with the ring-loaded corrugated circular waveguide (RCWG) structure devised by the authors. The useful frequency bandwidth in which the corrugated horn is effective for the improvement of antenna properties is limited by the frequency characteristics of the horn-aperture field and input VSWR of the horn. By the precise analysis of the RCWG, the maximum frequency range in which the desirable field is obtained is much wider than that in the conventional corrugated circular waveguide, and is achieved almost independent of ring thickness, when ring width is about 20 percent of slot depth. The characteristic impedance of the RCWG is nearly equal to that of the homogeneous circular waveguide when ring thickness becomes large. Therefore, a good transformer between the RCWG and the homogeneous circular waveguide is achieved by increasing ring thickness from the RCWG toward the homogeneous waveguide. From the above investigations, it is found that in the ring-loaded corrugated horn, the useful bandwidth is 1.35 times broader than that in the conventional corrugated horn. The theoretical results are verified by the experimental results.     

The Impact of Slow-Wave Modes on the Radiation Performance of a Corrugated Horn Antenna

Corrugated horn antennas offer many advantages compared with other waveguide radiators. A major disadvantage which is inherent with the design of a corrugated horn is the fact that slow-wave modes may exist within the horn antenna. In this paper far-field measurements of a W-band horn antenna are presented. The experimental data is compared with simulated data to confirm the presence of slow-wave modes. The analysis is completed by determining the waist, the gaussicity and the phase center location of both the experimental and model data. Finally a redesign approach is proposed which suppresses the slow-wave modes and therefore increases the usable bandwidth of the horn antenna.     

Ka 波段紧缩场天线的设计

设计了一个Ka 波段紧缩场天线。馈源设计结合角锥喇叭在反射面边缘照射电平下降快与波纹喇叭波瓣宽度宽的特点,通过给角锥喇叭加扼流套的改进设计来实现对反射面的照射。反射面采用锯齿型边缘来降低边缘的绕射作用,并进一步在无法加工锯齿部位贴附三角形吸波材料来减小绕射对静区特性的影响。暗室内采用平面测量结果表明,Ka 波段紧缩场天线静区特性满足设计指标要求。     

A hybrid technique for analyzing corrugated and noncorrugated rectangular horns

A hybrid technique is proposed to solve the entire problem of corrugated and noncorrugated rectangular horns without the usual approximations. The horn antenna is simulated by a multistepped waveguide structure radiating into half-space. The procedure is composed of three steps. First, assuming the horn to be terminated by infinite metallic flange, the aperture problem is accurately solved by a hybrid modal-spectral method (HMSM). Second, the modal analysis (MA) method and scattering matrix concept of waveguide discontinuities are employed to solve the transverse multidiscontinuity problems. Finally, the two methods are combined (MA-HMSM) to solve the entire problem of the horn antenna. The proposed technique allows to obtain not only the radiation patterns, but also the reflection and near-field characteristics of the horn, without any restriction on the geometry (semiflare angles, profiled horn contours, corrugations). A good agreement between theoretical predictions and experimental results has been obtained for several horns.     

Ultra-wide band corrugated gaussian profiled horn antenna design

Nowadays, an increasing number of applications need stable radiation patterns with low sidelobes and low crosspolar levels in a very wide bandwidth. Gaussian profiled horn antennas (GPRAs) have demonstrated their feasibility as one of the best solutions. A corrugated Gaussian horn antenna design with more than 40% bandwidth is proposed. The measured radiated far field patterns are in good agreement with the simulated ones. The measured results show a Gaussian antenna with extremely wide bandwidth, low sidelobes, and low crosspolar levels     

一种超宽频带高效率波纹喇叭的设计

设计了一种90°波纹喇叭作为天线馈源。由经典理论得出喇叭尺寸,利用HFSS进行仿真、综合优化,并根据某些关键尺寸对性能指标的敏感程度给出了合适的公差。工程实现表明：该波纹喇叭的仿真结果与实际测试结果基本一致;工作带宽〉40％,也验证了其超宽带特性。     

Calculation of the field radiated by horn-antennas using themode-matching method

Methods employed for evaluating fields radiated by horn antennas, like the aperture field method and the spherical wave expansion, have not taken into account the contribution by fields existing outside the horn aperture (e.g., along the outer walls of the horn). The use of the mode-matching technique for analyzing the transition from horn antenna to free space makes it possible to include in the analysis even those fields which exist outside (e.g., behind) the horn aperture when determining the far as well as the near field. Furthermore, the effects of the finite wall thickness and the discontinuity caused by the transition from waveguide to free space are also taken into account. A suitable development of the fields at the transition of the conical/corrugated horn to free space using the mode-matching technique is presented. Two different convergence diagrams, depending on the kind of modes excited in the horn antenna, are given. They show the results from extensive convergence investigations. With the help of these diagrams, a reliable evaluation of the fields radiated by horn antennas is guaranteed. Practical measurements of the fields radiated by horn antennas confirm the field distributions gained through analysis     

Corrugated horns

The corrugated horn has become the preferred choice of antenna for use in high-performance microwave reflector antennas for communications, radar and remote sensing. The principles and attributes of corrugated horns are explained. The analysis, design and manufacturing techniques and types of horns in use are briefly discussed     

Pattern analysis of corrugated horn antennas

The corrugated horn has been established as an antenna with low sidelobes and backlobes, rotationally symmetric patterns (for square pyramidal and conical horn shapes), and broad-band performance [1]-[9]. These properties make this horn useful for many applications. Previous studies have used conventional aperture integration techniques to evaluate the patterns of the corrugated horn. In general, the near axisE-plane radiation pattern of a pyramidal corrugated horn may be adequately predicted from standard analysis established for theH-plane patterns of conventional horn geometries [3]. This method, however, fails to predict the far-out sidelobe and backlobe radiation levels. The work presented here uses a knowledge of the aperture fields to predict the pattern using aperture integration and diffraction theory. The assumptions made concerning the aperture fields were verified by probing the internal fields and aperture fields of anXband corrugated horn. The results of this field probing are contained in the Appendix. The method of solution used in this paper parallels that used in previous publications [10]-[12]. Specifically, the pattern in the main beam region is computed using conventional aperture integration procedures, the contribution of theH-plane edges is found using a slope diffraction analysis, and the contribution of theE-plane edges is found by use of duality.     

大张角波纹喇叭在环焦反射面天线中的应用

将大张角波纹喇叭应用到环焦反射面天线的设计当中,在满足电性能要求的同时,可以很大程度上缩小反射面天线馈源的体积,具有结构紧凑、重量轻、电性能优异等特点,为同类反射面天线的馈源设计提供一个良好的借鉴。     

准太赫兹波段角锥波纹喇叭天线的设计

波纹喇叭天线是20世纪70年代出现的用于微波天线的一种新型器件,它结构紧凑、加工方便、成本较低。不仅如此,它还是一种高效率的馈源,它的方向图具有低旁瓣、轴对称、交叉极化小等一系列优点,因而得到广泛的应用。文中介绍了准太赫兹角锥波纹喇叭天线的基本设计思想。设计了一种工作在140 GHz左右频段的E面波纹角锥喇叭天线。计算机模拟达到了相对于平壁角锥喇叭来说较小波瓣宽度,极低旁瓣电平,E,H面波瓣图趋同的效果。