A rigorous cad of millimeter wave bandpass filter with all-metal insert in waveguide

In this paper, a bandpass filter with all-metal insert, an inductive strip in the E-plane of a waveguide is analyzed by a prototype filter and the scattering matrix of the strip is calculated by electromagnetic fields theory theoretically. By means of matrix combining technique, the scattering matrix of a bandpass filter of this type is obtained. And a rigourous error function is used to optimize the CAD program by Powell's method and make the experimental results agree well with the theory design at V-band.     

A Novel E-Plane Waveguide Filter with Three Metal Irises

This paper presents a novel E-plane rectangular-waveguide filter with three metal irises in Ka bard. Comparing with the conventional E-plane waveguide filter with single iris, a great improvment has been made in stop-band of a band pass filter, and wider pass band compare to normal double metal irises waveguide filter. An analysis is given by mode match method and the conservation of complex power technique [1]. Computer-aided design of a new five-resonator Ka band band pass filter has been presented, good agreement has been observed between theory and measurement data.     

A simplified CAD of millimeter-wave diplexer with E-plane T-junction and all-metal insert filters

An equivalent circuit theory design of a class of rectangular waveguide E-plane T-junction diplexer with E-plane all-metal insert filters is presented. Element values of equivalent circuit models of E-plane T-junction proposed in [1] are computed and approximated. The parameters of the filters designed by [2] are also given. By use of the network combining technique, the scattering matrix of the diplexer is obtained and optimized according to the diplexer specification with a novel objective function. The experimental results show a fairly good agreement with the computed results. The author was a visiting research fellow of the Bradford University during the period of this research project carried out.     

IMPROVED GENERALIZED ADMITTANCE MATRIX TECHNIQUE AND ITS APPLICATIONS TO RIGOROUS ANALYSIS OF MILLIMETER-WAVE DEVICES IN RECTANGULAR WAVEGUIDE

An improved generalized admittance (GAM) matrix technique is presented in this paper. Matrix transformation eliminates the singularity factor of GAM, denominator (1+Γ), because of new presentations of GAM. The relationship equations between II-port current and I-port incidence wave is computed by mode matching method. The generalized scattering matrix (GSM) of waveguide structure and its discontinuity problems is obtained with relationship equations and reflection coefficients. The GSM’s of millimeter-wave multistepped bend and T-junction in rectangular waveguide are computed by the improved GAM technique. The results comparisons between the proposed method and commercial software HFSS10.0 show the validity of the proposed method, which improves the validity of the GAM technique and reduces mathematical efforts. It is general, very efficient and can be used to solve other complicated and multiport network problems.     

Dispersion in finlines on semiconductor and the S-parameters of a step discontinuity

The Transverse Transmission Line method is used for the characterization of bilateral and unilateral finlines on a semiconductor substrate and in conjunction with the modal method, for the calculation of the scattering parameters due to a step discontinuity on a unilateral finline with a lossless dielectric substrate.Numerical results of the effective dielectric constant, attenuation constant and characteristic impedance for the bilateral and unilateral finlines on semiconductor substrates, and results of scattering parameters of a step discontinuity for unilateral finline, are presented.     

Analysis of waveguide inserted by a metallic sheet of arbitrary shape with the method of lines

In this paper, one type of waveguide three-dimension discontinuity, rectangular waveguide inserted by a metallic sheet of arbitray shape with zero thickness, is firstly analysed by using the Method of Lines. This waveguide discontinuity can be regarded as basic unit of microwave and MMW passive components and active circuits. Numerical results are in good agreement with physical meanings and other published data. Numerical results of several characteristics are presented at the end of the paper, including convergent characteristic of which the scattering parameters are depended on the number of discretization lines, dependence of scattering parameters on the size of metallic sheet and frequency response of scattering parameters.     

Design of 40 GHz-Band Iris-Type Waveguide Bandpass Filter

In this paper, a design method of an iris-coupled waveguide bandpass filter having 0.1 dB passband ripple and 3.5% ripple bandwidth at the center frequency of 41 GHz is described. Mode matching method is used to analyze H-plane discontinuity of waveguide and an equivalent circuit of the thick inductive obstacle is obtained from the results of the analysis. Simulation and experimental results show the validity of waveguide bandpass filter design method using mode matching method.     

横向电感膜片微波矩形波导的传输特性

以微波传输线等效二端口网络模型等效电路理论近似分析了含有横向电感膜片矩形波导的结构。计算发现,矩形波导内置一对膜片时膜片的宽度会影响散射参数的相位和振幅,而膜片放置的位置对散射参数的幅值及带宽没有影响。根据微波无反射传输的条件,研究了微波矩形波导内置两组横向电感膜片结构的转移矩阵。采用Matlab编程计算,得到在插入衰减最小时两组膜片在波导中的最佳间距。等效电路理论计算结果与用CST软件仿真的结果相符。研究发现,在膜片间距取最佳值时,两种方法得到的相对带宽差值仅为0.59%。     

Scattering characteristics of 3-D discontinuity consisting of semiconductor sample filled in waveguide with gaps

The scattering characteristics of 3-D discontinuity consisting of II-VI-epitaxial layer grown on lossy dielectric substrate inserted in the waveguide with gaps are investigated in detail by the method which combines the multimode network theory with the rigorous mode matching procedure. The experimental data verify the accuracy and the effectiveness of the present method.     

The sharpness-induced mode stopping and spectrum rarefication in waveguides with periodically corrugated walls

Abstract

Starting from the rigorous excitation equation, the propagation of waves through a 2D waveguide with the periodically corrugated finite-length insert is examined in detail. The corrugation profile is chosen to obey the property that its amplitude is small as compared to the waveguide width, whereas the sharpness of the asperities is arbitrarily large. With the aid of the method of mode separation, which was developed earlier for inhomogeneous-in-bulk waveguide systems [Waves Random Media 2000; 10: 395], the corrugated segment of the waveguide is shown to serve as the effective scattering barrier whose width is coincident with the length of the insert and the average height is controlled by the sharpness of boundary asperities. Due to this barrier, the mode spectrum of the waveguide can be substantially rarefied and adjusted so as to reduce the number of extended modes to the value arbitrarily less than that in the absence of corrugation (up to zero), without changing considerably the waveguide average width.     

Generalized Modal Scattering Matrix of Bandpass Filters Using Ridged Waveguides

Simple and accurate integral equation formulation using a three dimensional finite element (3DFEM) to determine the propagation of microwave passive structures is presented. This technique is applied to solve the scattering problems due to various forms of irises in lossless rectangular waveguide.The analysis of these components is highly dependent of the numbers of modes considered in the neighbourhood of the discontinuity. The theoretical model is compared with measurements and Mode Matching Method (MMM). Results are found to be good agreement.     

Ka波段波导滤波器的设计

采用高精度三维电磁场分析软件对电感膜片建模,并与等效电路相结合设计波导带通滤波器。实验结果表明,样品测试结果与仿真结果基本吻合,该方法不仅适合波导滤波器设计,也适合其它谐振器耦合结构滤波器的设计。     

FDTD-analysis of the wave diffraction from dielectric waveguide discontinuities

The problem of the guided mode reflection from the planar dielectric waveguide end is studied by the finite difference time domain method. The influence of facet deformations on the scattering characteristics is considered. The reflectivity problem for the system with the nonlinear dielectric waveguide insert is examined.     

Acoustical scattering by arrays of cylinders in waveguides

Multiple scattering of acoustic waves in a planar horizontal waveguide by finite-length cylinders is considered. Cylinder height equals the waveguide depth, and both are vertically constrained by the pressure-release boundaries. An analytically exact solution is obtained via normal mode expansion method in conjunction with the concept of the T matrix. The problem is decomposed into an infinite number of two-dimensional multiple scattering problems, modulated by waveguide mode shapes. Examples are presented for an isovelocity waveguide in which the medium is uniform and the waveguide depth is constant. It is found that, in numerical computations, including one or two evanescent modes captures the essence of the evanescent modes. Multiple scattering in the waveguide is compared with the corresponding two-dimensional case. It is concluded that, in low frequencies, the wave patterns in the two cases are very similar, with a shift in the frequency. The similarity diminishes when there are multiple propagating modes. Despite the mode mixing, some key features in the scattering as observed in the two-dimensional problem remain observable in the waveguide case.     

A new type of millimeter wave-integrated directional couplers

In this paper a new type of millimeter wave integrated directional coupler is proposed. The coupling mechanism on the narrow wall of waveguide consists of a series of bilateral E-plane slots deposited on a dielectric substrate by photo-etching technique. The modified generalized transmission parameters considering the thickness effects of the strips and higher order mode interactions at the step discontinuities in the coupling region are used in optimizing program. The calculated performance of a 3-dB 12-slot directional coupler at Ka-band is given. A prototype Ka-band coupler has been tested. The measured results agree with the theoretical prediction satisfactorily.     

Mode characteristics of nested eccentric waveguides constructed by two cylindrical nanowires coated with graphene

A kind of nested eccentric waveguide constructed with two cylindrical nanowires coated with graphene was designed. The mode characteristics of this waveguide were studied using the multipole method. It was found that the three lowest modes (mode 0, mode 1 and mode 2) can be combined by the zero-order mode or/and the first-order modes of two single nanowires. Mode 0 has a higher figure of merit and the best performance among these modes within the parameter range of interest. The mode characteristics can be adjusted by changing the parameters of the waveguide. For example, the propagation length will be increased when the operating wavelength, the minimum spacing between the inner and outer cylinders, the inner cylinder radius and the Fermi energy are increased. However, when the outer cylinder radius, the dielectric constants of region I, or the dielectric constants of region III are increased, the opposite effect can be seen. These results are consistent with the results obtained using the finite element method (FEM). The waveguide structure designed in this paper is easy to fabricate and can be applied to the field of micro/nano sensing.     

非线性光波导中基波和二次谐波的模场分布研究

非线性波导是一种重要的光量子器件。采用马卡梯里近似,可以近似描述波导的模场分布特征。针对ee-e准相位匹配的周期极化铌酸锂波导,分析波长为1 064 nm的基波和532 nm的二次谐波的基模模场分布。结果表明:如果波导为嵌入型正方形波导,基波和二次谐波的光斑基本为圆形,基波场分布范围较大;在截面正方形边长为5 μm并且芯区比包层折射率略高0.02时,波导就能将两种光波场基本约束在芯区中,但是这种波导边长为0.5 μm时约束能力就变得很差;如果采用芯区与包层折射率差别较大的波导,芯区边长为0.5 μm就可以将两种场分布基本约束在芯区中。结果对分析其他类型的非线性波导的模场分布具有指导意义。     

Electron acceleration considering pondermotive force effect in a plasma-filled rectangular waveguide by microwave radiation

The electron acceleration inside the plasma-filled rectangular waveguide is numerically investigated for the externally injected single-electron model considering the effects of density modification under a balance between the ponderomotive force and the pressure gradient force. Using Maxwell’s equations, we evaluate the field components of the fundamental mode in the plasma-filled rectangular waveguide, where the obtained equations are solved numerically using the fourth-order Runge–Kutta method for the electric field amplitude of the microwave. Besides, by solving the relativistic momentum and energy equations using the fourth-order Runge–Kutta method, the deflection angle and the total energy of the electron in the waveguide are obtained. Furthermore, it is shown that the electron energy gain can be controlled using superposing microwave fundamental modes. Effects of various parameters on the results are graphically presented.     

NETWORK CHARACTERIZATION OF STEP DISCONTINUITY WITH GENERALIZED CONSERVATION OF COMPLEX POWER TECHNIQUE AND ITS APPLICATION TO ANALYZING PERIODIC DIELECTRIC WAVEGUIDES

The propagation of electromagnetic waves along open periodic, dielectric waveguides is formulated in the case that surface wave is guided and propagates normally to the corrugation. Our approximate analysis with the propagation characteristics is to consider a corresponding bounded waveguide problem in which perfect electric or magnetic walls are introduced, and the periodic corrugation is regarded as consisting of step discontinuities connected by a length of uniform slab waveguide. By properly taking into account of both surface modes and only a few non-surface-modes, a novel network approach is proposed for characterizing step discontinuity based on the generalized conservation of complex power technique (GCCPT). Employing solution selection rule (SSR), we can readily derive propagation characteristics in the Bragg interaction region. A number of numerical results are shown to demonstrate the usefulness of our approach.     

Modified surface plasmonic waveguide formed by nanometric parallel lines

In this paper, two kinds of modified surface plasmonic waveguides formed by nanometric parallel lines are proposed. The finite-difference frequency-domain method is used to study propagation properties of the fundamental mode supported by these surface plasmonic waveguide structures. Results show that the transverse magnetic field of the fundamental mode is mainly distributed in the face to face region formed by two rods. With the same geometrical parameters and the same working wavelength of 632.8~nm, in the case of rods with a triangular cross-section, the degree of localization of field is strong, i.e. the mode area is small, but the fraction of the modal power in the metal increases, so the effective index increases and the propagation length of the mode decreases. With the same geometrical parameters, relative to the case of a working wavelength of 632.8~nm, when working wavelength is large, the mode area of transverse magnetic field distribution is large, i.e. the degree of localization of field is weak, and the interaction of field and silver is weak too, then the effective index decreases, so the propagation length increases. The rounded radii of rods have a great influence on the performance of the surface plasmonic waveguides with rounded triangular cross-sections, but have little influence on the performance of surface plasmonic waveguides with rounded square cross-sections. Since the distribution of transverse magnetic field, effective index, propagation length and the mode area can be adjusted by the geometrical parameters, this kind of modified surface plasmonic waveguide can be applied to the field of photonic device integration and sensors.