圆锥光壁系统与介质充填波导的模转换计算

本文对介质环加载边界条件特征方程以及由章日荣和刘顺祥同志推导的介质环加载波导与光壁波导连接的模转换公式进行了具体计算。该计算结果用于有关的介质加载喇叭,表明其辐射特性的计算值与实测值非常一致。     

第十一章 介质环加载多模喇叭

<正> 介质环加载喇叭是由Toshio satoh在1972年首先研制成功的,我国杨世华等同志也用实验的方法研制成功这种喇叭。章日荣和刘顺祥等解决了介质环加载波导与光壁波导的模转换问题,导出了这种喇叭的工程设计公式。这种喇叭内有一节带着介质环的波导,从左面光壁波导入射的电磁波在此节波导内转换为介质环加载波导的混合模。这些混合模在其右边的光壁波导转换为TE模和TM模。适当选择介质环的参数和尺寸,可以使喇叭获得很好的辐射特性。     

脊位于窄边的四种加载介质波导传输特性的有限元计算

运用矢量有限元方法对脊位于窄边的四种加载介质双脊波导的主模截止波长和单模带宽特性进行了计算和分析,四种波导分别为脊位于窄边的加载介质双脊矩形波导、加载介质双脊梯形波导、加载介质双脊V形波导以及加载介质双脊椭圆形波导。计算结果表明,脊位于窄边的四种加载介质双脊波导的两种传输特性总体相似,和脊位于宽边相比,脊位于窄边的主模归一化截止波长和单模带宽总体小很多,且脊位于宽边时的特性变化趋势比脊位于窄边时剧烈。这些计算结果将有助于微波器件及微波系统的设计。     

波导介质不连续性问题的FEM/PML方法分析

将完全匹配层(PML)与矢量有限元方法(FEM)相结合对波导介质不连续性问题进行分析。利用PML对计算区域进行截断，大大节省了FEM分析问题的内存消耗。对波导的单介质块加载问题的S参数进行了分析计算，数值结果与文献结果一致。在此基础上，计算了多介质块加载波导的散射参数。数值结果证实了应用FEM／PML方法对波导介质不连续性问题进行分析的正确性与有效性。     

脊位于窄边的介质加载双脊波导场结构的计算

将矢量有限元方法应用到脊位于窄边的四种加载介质双脊波导的场结构特性计算中,这其中包括脊位于窄边的加载介质双脊矩形波导、脊位于窄边的加载介质双脊V形波导、脊位于窄边的加载介质双脊椭圆形波导以及脊位于窄边的加载介质双脊梯形波导。多种模式的场结构特性随脊尺寸的变化而变化,其图形结果将有助于微波器件的设计。     

双层介质加载等离子体微环的高灵敏生物传感

为了提高介质加载表面等离子体的传输距离,提出了基于双层介质加载的表面等离子体波导结构。利用有限元方法研究了介质加载的表面等离子体波导的模场分布及传输特性,并对其传感应用的波导灵敏度进行了分析。研究表明, 当低折射率介质厚度占波导总厚度的33%时,传输距离是单层介质加载表面等离子体波导的2.4倍。利用该波导结构组成的微环谐振腔被用于生物传感研究,其传感特性分析表明,传感灵敏度为411 nm/RIU,检测极限为1.210-5 RIU。双层混合介质加载表面等离子体波导的设计和研究为其进行无标记生物传感应用提供了有价值的指导。     

圆波导铁氧体锁式变极化器的阻抗匹配研究

本文对铁氧体环加载圆波导锁式变极化器进行了阻抗匹配研究。从而提出了一种设计铁氧体环加载圆波导变极化器阻抗匹配的方法。推导出了/4阻抗匹配的计算公式,计算得到了阻抗变换器的尺寸,测试了实际样品的匹配性能,实测结果和理论计算吻合得很好。     

介质加载相控阵天线的模式分析法

应用模式分析法分析介质加载矩形波导相控阵天线的反射特性。这一方法适用于分析任意周期格栅的波导阵列天线,同时考虑了阵列表面覆盖介质罩、波导内加载介质或介质塞等的影响。应用Galerkin法,使在天线阵表面满足边界条件,可以确定波导内波导模的系数和辐射半空间Floquet模的系数,并可以把天线的输入导纳表示成N阶和N-1阶两行列式的比(N是使用的波导模数)。通过对几种不同结构的阵列天线的计算,所得结果和已知结果符合良好。     

介质加载异形波导的高阶模（LS模）

通过对介质加载矩形波导ＬＳ模场的分析，采用微扰法推导出介质加载异形波导ＬＳ模场截止频率的近似计算公式。实验数据与理论计算结果的吻合，说明了近似公式可用于微波器件特别是脊波导器件的工程设计和研制，并为此提供理论依据。     

圆皮导介质加载锁式铁氧体变极化器的实验研究

在实验基础上，本文给出圆波导锁式铁氧体变极化器的介质加载的研究结果。实验表明，在铁氧体环内适当加载介质，可明显提高器件的相称，而对插入损耗特征影响甚微，这一发现对改进器件性能，具有极大的实用价值。     

Radiation characteristics of a waveguide excited dielectric sphere backed by a metallic hemisphere

The experimental results of the radiation characteristics of waveguide excited dielectric spheres backed by metallic hemispheres are reported. The test antenna consists of a dielectric loaded hemispherical horn excited by a circular waveguide. The test data have shown that such a structure produces a radiation pattern with low sidelobe levels, increased on-axis gain, and reduced 3 dB beamwidth as compared to a waveguide excited dielectric sphere of same diameter and an optimum horn having an aperture of identical cross section area. Also, it presents a low VSWR over the waveguide band.     

Analysis of dielectric loaded hybrid mode coaxial horns

This article presents a numerical solution for radiation from a novel coaxial horn with a partial dielectric loading. The horn is represented as a set of three-layer dielectric loaded coaxial waveguide sections. Characteristic equation has been obtained to calculate phase coefficients for hybrid modes in each section. Applying mode matching technique generalised scattering matrices for each junction between the sections have been obtained, besides that power coupling integrals for each of three different type of junctions have been found in closed-form solutions. Cascading these scattering matrices with transmission matrices of each section yields a generalised scattering matrix of the horn. For the given excitation at the throat of the horn, amplitude and phase of eigenmodes at the aperture of the horn have been determined. Finally, Fourier transform integral of the aperture electric field has been applied to solve radiation problem of the horn. Numerical results on propagation and radiation characteristics of the first four hybrid modes of the horn are presented and it is validated that this solution can be successfully used for full-wave electromagnetic analysis and optimisation of multiband dielectric loaded coaxial feeds.     

基于介质波导混合模式的双频馈源喇叭天线

随着大型反射面天线技术的不断发展,天线系统对设备功能的多样化与一体化提出了更高的要求,馈源作为大型反射面天线的核心,其性能决定了反射面天线整体特性.文章基于介质波导混合模式提出了一种介质加载双频馈源喇叭天线,工作于X(7.25～7.75 GHz)/Ka(21～22 GHz)频段.利用特征值理论求解双层介质波导中电磁场表...     

矩形波导铁氧体移相器的有限元分析

本文从麦克斯韦方程推出适合于解决导磁率为张量形式的各向异性介质加载波导本征值问题的全电场有限元方程,讨论识别主模的方法和如何把两种不同媒质界面上的边界条件引入有限元方程。通过所建立的有限元方程,分析了双板铁氧体加载矩形波导的传播特性,并同解析解作比较,两者所得结果吻合得很好。     

Ku band pattern reconfigurable substrate integrated waveguide leaky wave horn antenna

A dual band substrate integrated waveguide H plane sectoral horn antenna with reconfigurable radiation characteristics has been proposed in this paper. Designed antenna acts as a perfect broadside radiator at 16.1 GHz and perfect endfire radiator at 14.4 GHz frequency. Broadside radiation has been achieved by etching rectangular slots in the flared section of horn exhibiting a gain of 8.87 dBi. To achieve perfect endfire radiation, dielectric loading is done at the edge of horn and at this frequency antenna shows a gain of 11.3 dBi. The horn and the loaded dielectric are integrated by using the same single substrate resulting in easy fabrication and low cost. The proposed design has been fabricated and measured results are in good agreement with the simulated results.     

Exploratory Study of a Millimeter Resonance Isolator for the Circular Electric Waveguide Mode

A feasibility study was made on a TE/sub 01/ mode circular waveguide resonance isolator at frequencies near 35 Gc. A design was developed which utilized circumferentially oriented and magnetized thin rings of hexagonal ferrite material in contact with the inner or outer surface of a ring of alumina ceramic mounted concentrically in the waveguide. Approximate experimental measurements indicated that appreciable nonreciprocal attenuation could be obtained without severe degradation of the mode purity. Expressions are given for the field distributions in the dielectric ring loaded wave guide and for the ellipticity of the magnetic fields at the surfaces of the ring. Magnetic field ellipticity is computed as a function of a "slow-wave mode" cutoff constant for an experimental ring configuration. For sufficiently large values of this constant, the magnetic fields at the boundary are almost circularly polarized and are relatively independent of mean ring radius. The analytical results tend to support the experimental findings.     

Analysis of soft and hard strip-loaded horns using a circularcylindrical model

Strip-loaded horns with transverse (soft) and longitudinal (hard) strips are analyzed theoretically. The method is based on a circular cylindrical and uniform waveguide model with a periodic strip structure. The field is represented by an infinite series of space harmonics (Floquet modes) in the air-filled central region and in the dielectrically filled wall region. The tangential field is forced to be continuous across the air-dielectric boundary. The propagation constant and the total field (including the hybrid factor) can be determined by solving the resulting matrix equations. The convergence of the solution has been accelerated by calculating the higher-order terms analytically. It is shown that the soft-strip-loaded horn in principle exhibits the same electrical behavior as a corrugated horn. The horn represents an interesting alternative to the corrugated horn in wide-band or dual-band applications, in particular for millimeter waves and for lightweight applications onboard satellites. The hard-strip-loaded horn has potentially high gain and low cross polarization over a certain frequency range, dependent on the horn dimensions, thickness of the dielectric wall and on how strongly the stripline modes are being excited     

A multipole analysis of a dielectric loaded coaxial rectangularwaveguide

A multipole analysis of a coaxial rectangular waveguide whose inner conductor is circular is made in order to determine the TE and TM modes of the system. The analysis is based on using multipole (dipole, quadrupole etc.) electric and magnetic current sources to generate field solutions in the waveguide. These solutions are used to match the electromagnetic boundary condition in a homogeneous coaxial rectangular waveguide and to determine the TE and TM eigenvalues of the waveguide system. Eigenvalue results are compared with results of the generalized spectral domain method and to eigenvalue results for a ridged waveguide. Propagation in a coaxial rectangular waveguide is also studied when the coaxial rectangular waveguide is loaded with lossy inhomogeneous dielectric material. A variational formula is used to relate the TEM, TE, and TM modes of an empty coaxial rectangular waveguide to the propagation in the loaded inhomogeneous dielectric waveguide     

Cutoff frequencies of an asymmetrically loaded cylindricalwaveguide

The cutoff characteristics of an asymmetrically loaded cylindrical waveguide are analyzed using the null-field method. The fields in the metallic waveguide and dielectric loading are expressed in their corresponding guided-wave modes. The addition theorem of the Bessel function is used to relate the fields across the air-dielectric boundary     

Dielectric ring resonators loaded in waveguide and on substrate

A rigorous mode matching technique is used to analyze the dielectric ring resonators loaded in a waveguide and on top of a substrate. Variation of several lowest order modes' resonant frequencies as a function of structure parameters is presented and is shown to be helpful for optimization of spurious mode separation. Two-dimensional electric and magnetic field line patterns and three-dimensional field intensity distributions of the ring resonators are plotted and provide information for mode excitation, coupling, and spurious mode suppression. Coupling between two dielectric ring resonators loaded in a metallic cavity are analyzed. The dielectric ring resonators are used to design a C-band elliptic function dual mode bandpass filter employing HE₁₁ modes. Experimental results are presented and show excellent agreement with the analytical solutions