Neural Computation of Wide Aperture Dimension of Optimum Gain Pyramidal Horn

A new method based on the multilayered perceptron neural network architecture for computing the wide aperture dimension of the pyramidal horn is presented. The computed wide aperture dimension is used in successfully designing optimum gain pyramidal horn. The other design parameters of the horn are determined from the simple and explicit analytical formulas. These formulas do not need the application of the iterative methods, and are not restricted to the high gain horn designs. The gain of a designed pyramidal horn is determined with no path length error approximation. Better accuracy with respect to the previous design methods is obtained for various pyramidal horn design examples.     

介质环加载喇叭的理论分析

本文对介质环加载边界条件特征方程进行了求解。导出了介质环加载波导与光壁波导连接处的模转换计算公式。并且根据这些公式计算了文献[1]设计的介质环加载喇叭的辐射特性,计算结果非常接近实测结果。     

Cross polarization from dual mode horn antennas

The cross polarization from dual mode horn antennas supporting the TE11and TM11-modes has been analyzed both theoretically and experimentally. The cross polarization has been shown to be strongly dependent on the length and flare angle of the horn. When the flare angle for a given horn length becomes larger than a certain threshold angle, the cross-polar sidelobes increase rapidly. Simple formulas for this threshold angle are presented. This cross-polar degradation will not occur if a plane phase front is provided over the horn aperture, either by profiling the horn or by applying a lens in the aperture.     

N槽结构波纹喇叭的理论分析

本文利用空间谐波法导出了N槽结构(每个周期有N个槽)波纹喇叭的特征方程和等效壁导纳的普遍公式,并把这些公式应用于双槽深波纹喇叭,给出了其等效壁导纳的表达式。文章还对一个双槽深波纹喇叭的等效壁导纳、特征值、口面模比和辐射方向图进行了数值计算,并与实验结果比较,两者吻合得很好。     

Cross polarization caused by perturbed circular cross sections of waveguides and horn antennas

The cross polarization caused by a perturbed cross section of the conical hybrid-mode horn is analyzed. The perturbed cross section is assumed to be slightly elliptical. The theory previously presented for cross polarization in a smooth-walled waveguide supporting theTE_{11}- mode is referred and applied to theHE_{11}-mode as well. Simple analytical formulas which are sufficiently accurate for small ellipticites of the cross-section ellipse are presented. These show that the tolerances on the waveguide diameter are extremely strong, typically on the order of 2 to4 times 10^{-2}mm in the horn throat for typical horn geometries at 12 GHz.     

K 波段喇叭天线增益的预测及外推法实测验证

为了研究采用基于远场Friss公式建立起来的传统三天线法测量天线的增益时所引起的误差、有限测量距离误差修正值的误差情况,以及我国常用来验证测量结果时所采用的解析式的误差,该文针对K波段的标准增益喇叭天线的增益,分别采用三种解析式(Jull公式、Schelkunoff公式以及Rao公式)和两种数值计算方法(矩量法-MoM和时域有限积分法-FITD)来进行计算,并提供了外推法(又称为广义三天线法)实测结果来做比较分析。为了说明外推法法测量结果的准确性(U=0.04dB,k=2),在附录中简介了外推法的测量原理。分析结果表明,对于K波段喇叭天线而言,在用于验证传统三天线法的测量结果的准确性时,由解析式计算的天线增益"理论值"需要慎重;而采用全波分析方法并考虑了喇叭壁厚影响的计算结果则比较准确。     

A correction to the available formula for the GTD near-field patterns of conical horns

An error in the geometrical theory of diffraction (GTD) near-field analysis of a conical horn published earlier is pointed out. This error is corrected, and the correct expression for the near-field patterns for the conical horn is presented. Computations based on the corrected formulas correlate better with results based on measurement as well as aperture integration technique [4].     

螺旋－圆锥喇叭天线的理论分析

本文建立了螺旋－圆锥喇叭天线的理论模型．通过研究外罩圆柱波导的薄套螺旋线这一新型结构，导出了螺旋－圆锥喇叭天线的特征方程，并推导出了其口径场、辐射场公式。通过分析特征方程，给出了快波辐射主模和慢波辐射主模的存在条件。运用导出的辐射场公式计算了螺旋－圆锥喇叭天线的辐射方向图，数值结果与已有实验结果吻合。     

A simple method for computing pyramidal horn gain proximity corrections

Pyramidal horn gain calibration by the two-antenna or three-antenna method, as well as measurements in the anechoic chamber that make use of standard gain horns, often require the application of proximity corrections. In this paper, a simple pyramidal horn proximity correction method is presented. This method is derivable directly from Jull's finite-range gain formulas, and is nearly as accurate as the frequently used and more laborious method of Chu and Semplak.     

Design and analysis of quasi-integrated horn antennas formillimeter and submillimeter-wave applications

The authors present a systematic process for the design of multimode quasi-integrated horn antennas, and provide a full range of practical antenna designs for millimeter- and submillimeter-wave applications. The design methodology is based on the Gaussian beam approach and the structures are optimized for achieving maximum fundamental Gaussian coupling efficiency. For this purpose, a hybrid technique is used in which the integrated part of the antennas is treated using full-wave analysis, whereas the machined part is treated using an approximate model. This results in a simple and efficient design process. The design procedure has been applied to the design of 20-, 23-, and 25-dB quasi-integrated horn antennas, all with a Gaussian coupling efficiency exceeding 97%. The designed antennas have been tested and characterized using both full-wave analysis and 91/370-GHz measurements. The quasi-integrated horn antennas are also examined as feed elements for Cassegrain antenna systems and are proved to be comparable to the traditional machined corrugated horn feeds     

a broad-band constant beamwidth corrugated rectangular horn

Using aperture field theory to predict the far-field radiation from a rectangular horn, a horn with substantially constantE- andH-plane beamwidths of17degand10degrespectively, is designed to operate over a 2.4:1 bandwidth. Assuming a cosine aperture field distribution in both theE- andH-planes of the horn, the general conclusion is first made that an aperture phase error of 0.37 wavelengths at the lowest operating frequency produces the least beamwidth variation (3 dB) over the band. A general design curve showing "constant" beamwidth as a function of horn throat length is produced, furthering the design of such horns with beamwidths in the range approximately9degto27deg. TheE-plane walls of the horn are corrugated, and to cover the bandwidth corrugations are comprised of "T-section" slots which are designed from a simple transmission line model. To realize the specified beamwidths, a compound horn configuration is adopted. Some experimental results obtained from a prototype horn are given.     

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.     

一种新型的双波束指向馈源喇叭

文章介绍了一种新型的馈源喇叭,这种馈源的设计,利用了喇叭反射面天线原理,实现了馈源的双频、双极化、双波束指向功能。文中重点讨论了这种喇叭的设计思想及波束特性的修正方法,给出了这种馈源喇叭特性的实际测量结果。     

High-Q resonances due to surface waves and their effects on theperformances of corrugated horns

We present a study of high-Q resonance phenomena that occur in corrugated horn structures. It is found that high-Q resonances occur within certain frequency bands where two types of modes, i.e., space-wave and surface-wave modes, simultaneously propagate. A simple model is presented to explain the resonance mechanism. The model yields the conditions for resonance, explains the Q of the resonance, and provides the associated resonant frequency. Approximate formulas for the upper and lower bound frequencies of a resonant band are obtained. It is found that the high-Q resonances deteriorate the gain and crosspolar performances of a horn even if the return losses are acceptable at some resonant frequencies. Rectangular corrugated horns are more susceptible to these resonances than circular corrugated horns, and the reasons for such a difference are explained     

ANALYSIS OF N-SLOT STRUCTURE CORRUGATED HORN

On the space harmonics technique general formulas are derived of the characteristicequation and the equivalent wall admittance of corrugated horns with N-slot structure(each periodhas N slots whose shape and depth may be the same or different).As an example,the calculatedradiation patterns for a corrugated horn having dual-depth corrugations show good agreementwith the measured ones.     

Compact multimode horn with low sidelobes for global Earth coverage

A new multimode corrugated horn is described for full-Earth coverage from a geostationary satellite. The horn has low sidelobes, low cross polarization, and is compact. We outline the design of this horn and compare its performance with other circular horn types, including conventional single and multimode-corrugated horns and dielectric loaded horns. A design was fabricated and measured results are described for return loss, radiation patterns, and axial ratio. These measurements demonstrate excellent agreement with computer predictions using mode-matching software     

Design of rectangular horn arrays with oversized aperture elements

The possible existence of blind spots, due to forced aperture resonances, is demonstrated theoretically and experimentally at 14 GHz in rectangular grid arrays of tapered rectangular horn elements with oversized (overmoded) apertures. The dominant contributor to these blind spots is the resonance of the equivalent transverse magnetic (TM_12) waveguide mode. The numerical results based upon our approximate methods of formulation and solution of the array boundary value problem agree well with experiments. A method for eliminating the blind spots by proper taper design is presented and experimentally verified. The analytical methods used in this work could possibly be extended to conical horus and other tapered-structure arrays as well as other periodic grid geometries. New simple and accurate formulas for the zeros of Bessel and Legendre functions and their derivatives are obtained as a result of this analysis.     

不同参数超宽带反射面天线系统辐射特性

在超宽带反射面天线设计中,首要问题是馈电天线的方向图与反射器匹配。以往在频域上对反射面天线的研究发现,当馈源天线方向图给出约-11 dB的边缘照射时,反射面天线可实现其最佳性能。在参数化模拟了作为馈源的透射电子显微镜(TEM)喇叭天线方向图特性的基础上,根据反射面天线的频域设计准则,相应地加入合适的超宽带反射面天线,对其远场辐射特性进行模拟计算。为了获得尽可能大的远场辐射场,采用计算机仿真技术(CST)数值模拟软件,在0 GHz~1 GHz频率范围内模拟了以不同参数TEM喇叭天线作馈源的超宽带反射面天线的远场辐射特性,并在时域上对其结果进行分析。模拟结果表明,由于其相位中心的不确定性,作为馈源的TEM喇叭天线无法与反射面天线完全匹配,其沿着反射面天线主轴移动时产生的反射面口径场相位和幅度的变化影响着远场辐射场的变化,TEM喇叭天线的遮挡效应也不容忽视。     

A simple design substrate-integrated waveguide horn antenna with reduced back lobe

ABSTRACT

A simple technique to design stable gain and low back lobe substrate-integrated waveguide (SIW) horn antenna is proposed. Matching is achieved by placing a metallised via in a specific distance from the aperture of the horn. The proposed design method is based on the analytical equivalent circuit that derived for the impedance of the antenna aperture and the matching metallic via in SIW. The aperture impedance and metallic via in SIW are studied and design curves are extracted for a specified substrate. Also, to reach a directive pattern and reduce the back lobe of the antenna, some chokes are used on the aperture of the horn. The effect of chokes on some parameters such as power flow and radiation pattern, the front to back ratio (FBR), side lobe level (SLL) and increasing directivity of the antenna is reported. The measurement results confirm simulation, appropriately. The proposed structure has high compactness due to the matching technique and design. The proposed SIW horn has compact dimensions as 18.7 * 23.34*7.62 mm (0.93 * 1.16 * 0.37 λ₀) and the measured gain of the horn is about 5.5 dB at 15 GHz and bandwidth of six percent.     

Finite-range gain prediction of pyramidal horn with improvedaccuracy

Expressions are presented for estimating the finite-range gain of pyramidal horns with improved accuracy. These are obtained by avoiding the conventional path length approximation in estimating the gain reduction factors, by a direct integration of the aperture field in the frequency range from 18 to 26.5 GHz, these expressions compare with available measured data on a pyramidal horn with an accuracy of better than ±0.15 dB, which is an improvement of about the same order over the earlier formulas