Theory and measurement of the field of a pyramidal horn

Edge-wave diffraction theory is used in an unconventional way to predict the field in the immediate vicinity of the aperture plane of a pyramidal microwave horn. The far field may then be inferred by Fourier transformation. The theoretical predictions for the near field are compared with measurements almost in the aperture plane and inside a horn made by the modulated scatterer method. The directivity on axis, which is our primary concern, is mainly determined by the curvature of the wavefront at the aperture. When computed as a function of frequency, it shows oscillations similar to those observed. They arise because edge waves, multiply reflected inside the horn, mimic the effect of a wave reflected back from the throat; this interferes with the main wave to change the curvature of the emerging wavefront, and hence, the directivity     

宽频带角锥脊喇叭天线的设计方法

主要研究了角锥脊喇叭天线的工作原理,给出了脊波导的截止波长、特性阻抗;提出了一种脊喇叭天线的设计方法,并运用该方法给出了设计实例。最后给出了实际测试曲线,验证了设计的正确性。     

Gain enhancement of a pyramidal horn using E- and H-plane metalbaffles

A technique for enhancing the gain of a wide-flare angle pyramidal horn is described. The gain of the antenna is increased by placing simple metal strips or baffles inside the horn near its throat. Two baffles, an E- and an H-plane baffle, are described and analyzed. The baffles are first analyzed through two-dimensional (2-D) numerical calculations and then through measurements in an experimental X-band horn. Each baffle enhances the antenna's gain in the respective plane. When the baffles are implemented together the gain enhancement is additive in decibels. The numerical calculations and measurements show that baffles can he used to significantly reduce the size of pyramidal horn antennas     

Analysis of pyramidal horn antennas using moment methods

A hybrid numerical technique is developed for electrically large pyramidal horn antennas radiating in free space. A stepped-waveguide method is used to analyze the interior surfaces of the horn transition. The electric field integral equation (EFIE) is employed on the outer surfaces of the pyramidal horn including the radiating aperture. Meanwhile, the magnetic field integral equation (MFIE) is used on the aperture to relate the aperture fields and those in the horn transition The resultant hybrid field integral equation (HFIE) is solved numerically by the method of moments. This formulation is both accurate and numerically stable so that high-gain microwave pyramidal horns can be analyzed rigorously. Far-field radiation patterns, both computed and measured, are presented for three electrically-large X-band horn antennas. The comparisons demonstrate that this method is accurate enough to predict the fine pattern structure at wide angles and in the back region. Computed far-field patterns and aperture field distributions of two smaller X-band horns are also presented along with a discussion on the validity of the approximate aperture field distributions routinely used in the analysis and design of pyramidal horns     

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     

Radiation pattern of a lens-corrected conical scalar horn

An expression for the radiation pattern of a lens-corrected conical scalar horn is derived. Computed radiation patterns are presented for scalar-horns feeds containing planoconvex and meniscus lenses in their apertures. The patterns and beamwidths are compared with those of an uncorrected wide-angle scalar horn and an open-ended corrugated waveguide.     

Design of multiple edge blinders for pyramidal horn reflector antennas

The design of multiple edge blinders for pyramidal horn reflector antennas is discussed. The blinders eliminate high sidelobes in the azimuthal plane near90degfor horizontal polarization at 4, 6, and 11 GHz. The successful design of multiple edge blinders for simultaneous operation in each of the three common carrier bands depends upon the suppression of an off-axis major lobe at 4 GHz and grating lobes which typically appear at 6 and 11 GHz. Using the blinder array factor and element pattern, it is shown that these lobes can be suppressed by properly choosing the blinder tilt anglebeta_{c}, the inclination of an individual blinder edgedelta, and an adequate number of edgesN.     

Steering of zeros in the directional pattern of a linear array

Beam steering for a linear array is discussed in terms of the independent angular steering of each zero in the directional pattern. The discussion is centered on the zero-steering network of Davies. The binomially weighted case is also derived.     

Influence of horn length on radiation pattern of oblique-flare-angle corrugated horn

The influence of horn length on the radiation pattern of an oblique-flare-angle corrugated horn is described. Two experiments with a 110° horn are reported. These show that a horn with three slots has a radiation pattern which is essentially the same as that of a horn with five slots. It is also demonstrated that the innermost slot has a dominant effect on the pattern.     

Optimization of the symmetric E-mode horn profile for a performance directivity pattern

The rigorous theory of excitation of an irregular electrodynamic system is used to formulate and solve the problem of determining the profile of a horn operating on symmetric E modes that provides a required mode structure at the output and an optimum directivity pattern.     

Calculation method for microwave pyramidal horn radiators with curvilinear generatrix

Calculation method for pyramidal horn radiators (PHR) with curvilinear generatrix has been developed on the basis of the theory of waveguide tapers. This method makes it possible to reduce the value of spurious reflection coefficients and transformation of the principal wave into waves of higher order modes by forming generatrixes of walls with specific curvilinearity.     

Wall reflection modelling for horn directional antenna at EHF

The effect of directional horn antenna radiation patterns is important to characterise an indoor radio channel. Instead of a single ray, the main possible rays of departure and arrival are considered according to the directional horn transmitter and receiver antenna radiation patterns using ray tracing. Computation results fit well with the measurements upon wall reflection at the EHF band.     

On primary incident wave models for pyramidal horn gain calculations

A few widely used primary incident wave models for pyramidal horn antenna analysis are compared on the basis of gain calculations. The analysis is based on edge-wave diffraction theory, as presented in a previous publication, with some modifications made to the underlying theory. It is shown that these models agree well for high-gain horns with small flare angles, but that the differences are more profound for lower gain horns, where the flare angles are larger. The accuracy of the various models are studied by comparing the results to actual measurements. The respective effects of amplitude and phase variation in the primary incident wave are also illustrated.     

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.     

局部方向数字模式算子的改进

局部方向数字(LDN,local directional number) 模式算子,用Kirsch边缘模板计算像素点8个方向的边缘响应 值,只能从1幅图像中获取64个特征值。为了提高该算子的特征提取 能力,提出了16邻域两种边缘 模板,利用了更多点的灰度信息计算边缘响应,可获得像素点更多方向的边缘响应,能从 图像中提取出更多的特征值。在ORL 人脸库、Yale人脸B库和Cohn-Kanade人脸库上的实验结果表明,边缘模板的改进,极大地 提高了LDN模式算子的特征提取能力, 采用16邻域的边缘模板使平均识别率 分别提高了11.5%和13.04%;并且,这种 改进还大大增强了算子对光照和噪声变化的鲁棒性。     

Near-field patterns from pyramidal horn antennas: numericalcalculation and experimental verification

The electromagnetic field close to a pyramidal horn antenna has been predicted using a numerical technique assuming a spherical phase front in the aperture of the horn. Comparison with experimental results using an infrared imaging technique has shown that the best fit is for a phase front that is 1.25 times more curved than a sphere. The infrared imaging method has been demonstrated to be very useful for mapping the fields in a region that is sensitive to the introduction of metallic probes     

一种应用于微波水分检测仪的角锥喇叭天线设计与分析

根据惠更新原理对比分析了几种常用喇叭天线的特性,依据角锥喇叭天线的设计理论,结合铁精矿水分微波检测仪的实际情况,设计了中心频率为9.4 GHz、增益大于10 dB的角锥喇叭天线结构.运用HFSS软件对该结构进行了仿真分析,通过仿真和对比分析得到一组较好满足工作需要的辐射增益方向图、驻波比等辐射特性,仿真结果验证了设计天线的可行性,为后期的试验和运行提供依据.     

Radiation pattern of a corrugated conical horn in terms of Laguerre-Gaussian functions

Many papers can be found on radiation properties of corrugated feeds. The radiated field is described either by means of the Kirchhoff-Huyghens formula, or with a spherical mode expansion. In both cases, especially where the horn is long, the computation may be important. In this letter we present a third method founded on a Laguerre-Gaussian expansion in cylindrical coordinates.     

The mode transformation and the radiation pattern of the dielectric-loaded horn

In this paper, the boundary condition characteristic equation of the dielectric-loaded guide and the characteristic values of the hybrid modes in it are given. The mode transformation equations between the dielectric-loaded guide and a general waveguide are also given. Then the computed radiation patterns of the dielectric-loaded horn made by Yang Shihua (1977) are introduced. The predicted and the measured radiation patterns superimpose each other satisfactorily.