周期性结构的边缘元分析

本文用边缘元、模匹配以及多模网络相结合的方法分析周期性结构。计算了ＮＲＤ波导周期结构和介质镜象线周期结合两个具体实例。数值结果表明这种方法用于分析周期性结构不仅是有效的，而且上仍很高的计算精度和效率。     

Periodic Structures and Their Application in Integrated Optics

Periodic structures are used widely in integrated optics for input-output couplers, bandstop filters, modulators, directional couplers, and distributed feedback lasers. An analytical discussion and review of these devices is given based upon the coupled-mode transmission-line analysis. Experimental results and performance characteristics are presented to illustrate the special features of each type of device. Finally, the usefulness of transmission-line analysis to the understanding and the design of these devices is pointed out.     

Effects of Randomization on Periodic Coupling

Previous analyses of periodically coupled multimoded systems have assumed equal spacing of the coupling points. In this paper, explicit simple formulas are developed to account for randomized variations of a periodically coupled system. This analysis is useful in multimoded transmission systems utilizing circular waveguides or fiber optics and in active systems such as traveling wave tubes and surface acoustic wave devices.     

An Investigation of Nonreciprocal Periodic Structures

The properties of a nonreciprocal ferrite-loaded rectangular waveguide, which is periodically loaded by thin metallic "inductive" diaphragms, are investigated experimentally. The propagation constants of the structure are measured and are compared with predictions based on measured values of the scattering parameters of a single diaphragm in the nonreciprocal waveguide. The agreement between theory and experiment is generally good except for the smaller spacings between the loading diaphragms. This discrepancy is attributed to the effects of higher order mode interaction.     

盘荷波导慢波结构色散特性的变分分析

盘荷波导慢波结构可以看成由无数多个波导不连续性组成，每个波导不连续性可用一个T型网络描述，其参数能用变分方法得到，再根据无耗的四端微波网络理论，可以得到这种慢波结构的色散方程，因此本文得到了一种用于计算盘荷波导慢波结构色散特性的变分法。该变分法获得的色散特性结果与用场匹配法和HFSS模拟获得的结果符合得比较好。     

Mode Coupling by a Longitudinal Slot for a Class of Planar Waveguiding Structures: Part II--Applications

Coupling between two parallel-plate waveguides is investigated. Mutual excitation is due to a Iongitudinal slot in a common plate. The introduction of reflecting boundaries parallel to the slot allows one to model a number of planar waveguiding structures featuring a common coupling mechanism. Part II of this paper presents specific examples of the above approach along with numerical results. Examples include a rectangular coaxial transmission line, broadwall-coupled rectangular waveguides, coupled microstrips, and coupled microstrip and rectangular waveguide.     

Mode Coupling by a Longitudinal Slot for a Class of Planar Waveguiding Structures: Part I--Theory

Coupling between two parallel-plate waveguides is investigated. Mutual excitation is due to a Iongitudinal slot in a common plate. The introduction of reflecting boundaries parallel to the slot allows one to model a number of planar waveguiding structures featuring a common coupling mechanism. Part I of this paper details the analysis of the basic slot scattering problem based on the singular integral equation method. If one assumes that the slot is small, then closed-form algebraic modal equations follow. These modal equations are well-adapted to numerical parametic studies.     

Mode Analysis and Q-Factor Enhancement Due to Mode Coupling in Rectangular Resonators

Modes in rectangular resonators are analyzed and classified according to symmetry properties, and quality factor (Q-factor) enhancement due to mode coupling is observed. In the analysis, mode numbers p and q are used to denote the number of wave nodes in the direction of two orthogonal sides. The even and odd mode numbers correspond to symmetric and antisymmetric field distribution relative to the midlines of sides, respectively. Thus, the modes in a rectangle resonator can be divided into four classes according to the parity of p and q. Mode coupling between modes of different classes is forbidden; however, anti-crossing mode coupling between the modes in the same class exists and results in new modes due to the combination of the coupled modes. One of the combined modes has very low power loss and high Q-factor based on far-field emission of the analytical field distribution, which agrees well with the numerical results of the finite-difference time-domain (FDTD) simulation. Both the analytical and FDTD results show that the Q-factors of the high Q-factor combined modes are over one order larger than those of the original modes. Furthermore, the general condition required to achieve high-Q modes in the rectangular resonator is given based on the analytical solution     

Vector Variational Solutions of Inhomogeneously Loaded Cylindrical Waveguide Structures

A vector variational formulation of the Maxwell curl equations in terms of all six electromagnetic field components is developed for circular waveguides symmetrically loaded with dialectric. A guide-wall boundary integral term, which renders the electric Dirichlet boundary conditions natural, is included in the variational expression. It is, therefore, unnecessary for the trial electromagnetic field functions to satisfy any guide-wall boundary conditions. This greatly extends the class of problems for which the vector variational-solution procedure is applicable and permits simple expansion functions for the trial fields, thus facilitating integral calculations. Solution results for several hybrid-mode circulator-waveguide structures are presented and compared with available experimental data.     

Calculating Periodic Structures Based on Ideally Conductive Squares

Journal of Communications Technology and Electronics - The applicability of the method for solving the problem of diffraction by resistive gratings, based on solving the problem of exciting the...     

Tapered Block Coupling and Mode Conversion in Integrated Optics

High-efficiency power transfer between two planar waveguides on separate substrates has been achieved via the tapered velocity mechanism. This method is simple and easily repeatable. The same setup can also be used as a mode converter as well as a mode filter.     

TE Waves in Arbitrary Periodic Slow-wave Structures with Rectangular Grooves

The dispersion characteristics of the transverse electric modes in a waveguide with circular cross-section and periodic rectangular surface corrugations with smoothed edges are examined by the space harmonic method. The whole structure is divided into two regions, one in the propagation area and one inside the grooves. In the first region, the Floquet theorem is applied and the field distribution is expressed as a summation of spatial Bloch components, while an appropriate Fourier expansion of standing waves is used inside the grooves. Applying the appropriate interface conditions, an infinite system of equations is obtained, which is solved numerically by truncation. Numerical results are presented for several cases to check the convergence and the accuracy of the method, as well as its dependence on the corrugation profile. This formalism could be easily expanded to include all kind of waves that can in principle propagate in such slow-wave structures.     

Finite-Element Time-Domain Analysis of Electrically and Magnetically Dispersive Periodic Structures

A formulation is presented for the finite-element time-domain (FETD) analysis of periodic structures that contain electrically and/or magnetically dispersive materials. The formulation is based on the previously developed transformed field variable approach and the Floquet absorbing boundary condition, which are both applicable to arbitrary scan or incident angles. The paper describes an implicit finite-element time-marching equation for the transformed electric field variable coupled with a finite-difference type equation for the evaluation of the transformed magnetic field variable. The technique is applicable to general dispersive materials, although the required convolution calculations can be greatly accelerated when the electric and magnetic susceptibilities can be represented by a pole expansion. Numerical examples are presented to demonstrate the validity and capability of the proposed numerical approach which is effective for the efficient broadband analysis of complex periodic structures such as engineered materials and phased-array antennas.      

Analysis and Calculations on Dispersion Relation and Coupling Resistance of Periodic Plasma-Cavities

The plasma tensor dielectric permittivity and electromagnetic field accurate expressions in the external axial magnetic field are obtained from the Maxwell’s equations and the double component plasma particle linear movement equations. Further, the flux of energy inside the plasma-cavity drift channel is presented. Based on them, some of the property of cavity passband dispersion and coupling resistance of plasma-filled coupled-cavities slow wave structure in different plasma density and magnetic field conditions is analyzed according to the numerical calculation.     

Dispersion Characteristics of Arbitrary Periodic Structures with Rectangular Grooves

The dispersion characteristics of a circular cylindrical waveguide with periodic surface corrugations consisting of rectangular grooves with smoothing are examined using the Space Harmonic Method (SHM). The whole structure is divided into two regions, one describing the propagation volume and one inside the grooves. In the first region, the Floquet theorem is applicable and the field distribution is expressed as a summation of spatial Bloch components, whereas in the second one an appropriate Fourier expansion of standing waves is used. Applying the boundary conditions an infinite system of equations is obtained, which is solved numerically by truncation. Several cases are considered, including the limiting cases of a sinusoidal and a rectangular corrugation profile, to check the accuracy of the method proposed as well as its dependence on the corrugation profile. Numerical results are presented only for transverse magnetic modes, although the formalism can be easily extended to include all kinds of waves that can in principle propagate in such a structure.     

单模光纤和单模激光器耦合理论与实践

本文对单模光纤、单模激光器的输出光束特性进行了分析,并利用高斯光束传输理论讨论了单模激光器与单模光纤、单模光纤与单模光纤之间的耦合问题。这种高斯近似分析方法,是一种简便、准确、实用的分析计算方法。     

Analysis of Dielectric Periodic Structures with Multi-Mode Network Method

The transmission characteristics of several dielectric periodic guiding structures are analyzed in this paper with a method, which the rigorous mode matching method is combined with the multimode network theory. The precision and effectiveness of the present method are verified by experimental data.     

Two Examples of "Confluence" in Periodic Slow Wave Structures

The properties that result from the elimination of a stop-band of a Iossless periodic slow wave structure are discussed. For two particular structures, it is shown that theory predicts a nonzero group velocity at the point of confluence of the two passbands. This confluence is desirable for linear accelerator structures operating at the /spl pi/-mode since it produces increased mode separation. Certain characteristics of zero and /spl pi/-mode confluence are also discussed.     

Experimental Determination of Wavelength in Dielectric-Filled Periodic Structures (Correspondence)

Let it be required to determine the guided wavelength in a dielectric-filled periodic structure, such as a corrugated wall or serrated waveguide. The accepted traveling probe technique requires a slot in the broad wall of the guide and a groove in the dielectric material. Even if the errors introduced by these modifications could be tolerated, other effects render this technique unsuitable, One of these is a surface-wave effect which resuIts in a measured wavelength higher than the one in the guide and lower than the free-space value. If the structure is dissipative, such as a serrated guide, more difficulties arise.