具有双槽结构模变换器的双频段波纹喇叭

从双频段波纹喇叭的辐射特性出发,确定了喇叭的口面参数,设计了喇叭的辐射段、变角段和光壁过渡段,并用球面波展开法计算其辐射方向图。研究了双槽结构模变换器不同的角度对喇叭的回波损耗、辐射特性及工作带宽的影响。设计了Ku/Ka双频段波纹喇叭,E面和H面辐射方向图保持良好的等化,回波损耗在Ku频段优于22 dB,在Ka频段优于30 dB。     

同轴波纹喇叭内部高频馈源特性研究

同轴波纹喇叭可用作双频段馈源或多频段馈源.纵槽波纹喇叭可以作为同轴波纹喇叭的内部高频馈源,除具有良好的辐射特性外,还具有较小的口面面积.文中利用模式匹配法对同轴馈源的内部高频馈源进行理论分析与研究,并对实际馈源进行了测试.实测结果与计算结果基本一致,从而验证了分析方法的正确性.     

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。     

纵向槽和径向槽组合波纹喇叭馈源的优化设计

研究了纵向槽和径向槽组合的波纹喇叭馈源的优化设计方法.基于旋转体时域有限差分算法分析波纹喇叭的性能,结合协方差矩阵自适应进化策略,以天线口径效率为目标,优化设计了一款Ku频段波纹喇叭馈源,并加工和测试了馈源样机.计算与实测结果表明,在10.7~12.75 GHz频带内,该喇叭具有良好的阻抗匹配和辐射特性,应用于标准卡塞格仑天线时,天线口径效率优于78%,验证了这种优化设计方法的有效性.     

一种Ka波段双槽波纹喇叭天线的设计

将轴槽和直槽相结合,设计了一种工作于Ka波段的新型双槽波纹喇叭天线,模变换段采用轴槽设计,辐射段采用直槽设计,通过仿真试验,获得了波纹喇叭天线轴槽和直槽的最佳数目,并在此基础上,优化了槽宽、槽深及光滑圆波导的长度,得到了辐射性能最佳的天线结构。将所设计的双槽波纹喇叭与传统的单槽波纹喇叭作为馈源,分别应用到卡塞格伦天线中进行了仿真试验。仿真结果表明,所设计的双槽波纹喇叭具有性能更优的辐射特性和驻波特性,作为馈源使用时,卡塞格伦天线在主极化方向上性能良好。     

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.     

波纹壁参数变化的波纹喇叭的理论分析

波纹壁参数(内径、等效导纳、及半锥角)按照特定规律变化,可以抑制有害的高次模,或产生适当数量的特定高次模,构成纯模或多模波纹喇叭,以改善喇叭的辐射特性和缩短喇叭的长度。本文导出了两种变参数(连续变化和折线式变化)波纹喇叭的设计公式。文中通过一个实例比较了复合式多模喇叭辐射场的计算值和实测值,其结果是满意的。     

第八章 波纹喇叭的辐射特性

<正> 在上述七章中我们已经论述了各种波纹喇叭的内场。由此可以得到喇叭孔径的电磁场,在本章中我们将要论述由喇叭孔径场计算其辐射特性的方法。按照一般面天线理论,可以用朱兰成辐射公式计算喇叭的辐射场。但对于小孔径喇叭,由于法兰和喇叭外壁的作用,交叉极化场的实测结果与朱兰成辐射公式的计算结果差别较大,因此对于小孔径喇叭朱兰成辐射公式只适用于主极化辐射场;而应该用所谓E场模公式计算交叉极化辐射场。孔径大小可以大致以三个波长为分界线。     

带—加载混合模馈源喇叭

本文介绍一种新型的混合模馈源喇叭。它是一空心的圆锥介质波导,外表面被金属化,内表面镀有周向排列的导带。如双槽深波纹喇叭一样,它可以在两个任意的分离频率上,设计成具有最小的交叉极化。与波纹喇叭相比,它有重量较轻、价格较低的优点。由于介质内传播场的有害辐射,小喇叭将有一些交叉极化。     

一种Ka频段超低交叉极化宽频带波纹喇叭天线

波纹喇叭天线是一种结构紧凑、具有良好辐射性能的馈源天线,特别是轴向槽波纹喇叭天线可以在宽频段内实现极低的交叉极化,对扩展工作频段、实现极化复用有重要的价值。文章对轴向槽波纹喇叭天线的设计方法进行了研究,利用模式匹配法和全波算法软件设计了一种Ka频段超低交叉极化宽频带轴向槽波纹喇叭天线。实测数据表明,该喇叭天线工作频段可覆盖整个Ka频段（26.5~40 GHz）,在频段内回波损耗小于-20 dB、交叉极化小于-45 dB,同时天线具备良好的方向图对称性和相位中心稳定性,在卫星通信领域具有广阔的应用前景。     

A novel horn radiator with high aperture efficiency and low cross-polarization and applications in arrays and multibeam reflector antennas

A step horn structure is presented that yields about 90% aperture efficiency with low cross-polar radiation. It is found that for obtaining high aperture efficiency, the horn aperture should consist of only the TE/sub z/ type of modes in appropriate amplitudes and phases. The desired TE/sub z/ modes are produced using multiple steps in the horn walls. The distances between the steps are critical to suppress the undesired TM/sub z/ modes. Radiation characteristics of high efficiency circular and square horns are presented and potential applications of such high efficiency horns are discussed.     

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     

Analysis of diagonal horns through Gaussian-Hermite modes

The radiation characteristics of diagonal horns are investigated by means of Gaussian-Hermite modes. It is shown that, for reasonably long horns, the beamwidths in the principal and 45° planes are equal to within 10%, and all sidelobes are below -15 dB. It is also demonstrated that the phase center of a diffraction-limited horn is close to the aperture, whereas the phase center of a constant-beamwidth horn is behind the throat. The maximum coupling to the lowest order copolar Gaussian mode is 84%, and the total amount of power coupled into the cross-polarized lobes is 9.5%. More significantly, the aperture efficiency of a Cassegrain antenna fed by a diagonal horn has a maximum value of 81%, which compares with 87% for a corrugated horn. The maximum efficiency is achieved when the aperture of a diffraction-limited horn is placed at a confocal tertiary focus, although a secondary focus gives an aperture efficiency that is only 10% lower, suggesting that diagonal horns are suitable for focal-plane arrays     

Classical axis-displaced dual-reflector antennas for omnidirectional coverage

The aim of this work is to discuss the synthesis and performance of classical dual-reflector antennas suited for an omnidirectional coverage. The reflector arrangements are axially symmetric with surfaces of revolution generated by axis-displaced conic sections, established from geometrical-optics (GO) standpoints to achieve omnidirectional radiation characteristics. Closed-form equations are derived for the design of all possible reflector configurations. The vector GO aperture field is also obtained, yielding an approximate analysis by the aperture method. Some pertinent geometrical characteristics and efficiency curves are then presented and discussed for several antenna configurations fed by transverse electromagnetic coaxial horns (for vertical polarization). A practical antenna design is conducted and analyzed by the method-of-moments technique, demonstrating the accuracy of the efficiency analysis yield by the aperture method for moderately large antenna apertures.     

Aperture efficiencies of large axisymmetric reflector antennas fedby conical horns

It is shown how the radiation patterns of conical horns can be understood in terms of Laguerre-Gaussian beam modes. This approach provides a simple method for calculating the horn radiation pattern as it propagates through a multielement optical system consisting of lenses or offset mirrors with large focal ratio and/or a small angle of incidence, and can be used in quantitatively determining aperture efficiencies for systems where conical horns are coupled to antennas via tertiary optics. The resulting aperture efficiency results and a practical quasioptical system fed by a conical horn are discussed     

基于SIW的多波束CTS阵列天线设计

文中设计了一款基于基片集成波导(SIW)的毫米波高增益多波束连续横向枝节(CTS)阵列天线,它通过切换馈电端口实现多波束功能。该天线整体结构简单,采用印刷电路板工艺实现。天线主要包含馈电喇叭、平面波转换结构以及辐射结构三个部分,由三层基板构成。馈源为基于SIW的馈电喇叭,并在口径处添加匹配结构以提高其辐射性能;平面波转换结构由SIW抛物面和渐变耦合槽组成,可将馈电喇叭辐射出的柱面波转换为幅度服从泰勒分布的平面波进而为CTS阵列馈电,因此天线具有低副瓣的特性;辐射结构为1×8的CTS阵列,通过优化缝隙宽度以保证每个单元辐射出相等的能量。天线工作在30 GHz,通过切换馈电端口可在±20°范围内实现波束切换,天线测试结果与仿真结果吻合,验证了设计的合理性。     

Hard waveguide feeds with circular symmetry for aperture efficiencyenhancement

Hard horns or waveguide feeds with circular symmetry have been studied with respect to gain (aperture efficiency) and crosspolarisation. The corrugated or strip-loaded representations of these feeds give almost identical radiation properties when surface waves are neglected. The contribution from the wall region increases the gain and crosspolar bandwidth of the feed. The gain increases and the crosspolar bandwidth decreases with increasing waveguide diameter and wall permittivity. The hard horns may be useful in cluster feeds and limited scan arrays due to reduced size and weight     

Optimization of Profiles of Rectangular Horns for High Efficiency

Realization of high-efficiency rectangular horns is investigated by means of mode generation and profile optimization. Conditions required for maximum efficiency of an aperture array are derived and made specific to a rectangular aperture with twofold symmetry. It is shown that aperture coupling has a significant effect on aperture efficiency through mode coupling. Efficiencies in excess of 100% are predicted for aperture sizes that are slightly greater than an odd multiple of half-wavelengths. The method described here results in more compact horns than obtained by using conventional linear tapers or steps. Results are presented for horns suitable for array feeds or directly radiating array applications that achieve aperture efficiencies close to 100% with horns of aperture size ranging from 1.25 to 3 wavelengths and at the same time have a return loss 20 > dB and cross-polar isolation > 22 dB. Measured results are given for an experimental compact horn that has high efficiency over an 8% bandwidth. The agreement between computation and measurement is within the limits of experimental error and this is obtained without any special surface treatment on the inside surfaces.     

Near-zone gain of 500 MHz to 2.6 GHz rectangular standard pyramidalhorns

Full-wave solutions to the problem of radiation by rectangular standard pyramidal horn antennas are presented. The radiation problem is formulated in terms of an electric field integral equation (EFIE), which is solved using the method of moments (MoM) for four rectangular standard pyramidal horns covering the frequency range from 500 MHz to 2.6 GHz. Results for the near-zone gains as a function distance from the aperture of the horn antenna are presented. A comparison is made with the analytical formula for the fields and near-zone gains