Obstacles In Rectangular Waveguide Research Articles

Domain Product Technique Solution for Scattering by Cylindrical Obstacle in Rectangular Waveguide

The canonical problem of scattering by a cylindrical obstacle in a rectangular waveguide is rigorously reexamined in the framework of the domain product technique. An accurate, rapidly converging algorithm is based on the efficient series representation of the field in a rectangular interaction region. It is shown that the fast convergence of the numerical approximation is stipulated by mathematical properties of the matrix operator arising from the boundary value formulation. The solution is also validated by comparison with the data of other authors. The approach proposed can be applied to the analysis of scattering by real metallic or dielectric posts placed parallel to the narrow or broad wall of the guide, in the theory of the circular-rectangular coaxial waveguide and the theory of other structures containing circular obstacles in the rectangular coupling region.

Efficient Analysis of Scattering By Arbitrarily Shaped Thin Obstacles in Rectangular Waveguide

A moment-method based analysis of arbitrarily shaped zero-thickness obstacles in rectangular waveguide is presented. The method is discussed in two well-known formulations, and for both of them an efficient Green's functions representation is introduced. The representation is obtained by extracting suitable terms representing the asymptotic behaviour of the TE and TM part of Green's dyad. Two different sets of basis functions are then compared in terms of accuracy of the numerical results obtained: rooftops and bilinear. It is shown that the higher order set of bilinear basis function leads to spurious results, whereas no such effect appears using rooftops. A very good efficiency of the overall algorithm was observed.

Single-Post Inductive Obstacle in Rectangular Waveguide (Reply to Comments)

In reply to the above comment, we would like to say that a more complete survey of previous work with inductive posts, which includes that of Abele, is presented in our paper on multiple-post inductive obstacles.

Single-Post Inductive Obstacle in Rectangular Waveguide (Comments)

Leviatan et al. have made, in the above paper, an important contribution to the theory of posts in rectangular waveguide, but unfortunately failed to reference the key paper by Abele [1]. Abele's technique was found to yield excellent results when used to design inductive posts for rectangular waveguide bandpass filters [2], and should be brought to the attention of readers of the TRANSACTIONS.

Lossy Inductive-Post Obstacles in Lossy Waveguide

Post and wall losses are treated for inductive obstacles in rectangular waveguide. Post losses are treated rigorously by moment methods and wall losses are obtained by perturbational methods. Losses may be taken into account by a modified equivalent circuit and a Iossy transmission line. Post losses may be comparable to wall losses.

Multiple-Post Inductive Obstacles in Rectangular Waveguide

A complete analysis of multiple-post inductive obstacles in rectangular waveguide is presented. A moment method solution with exponential ( e/sup jnTheta/) expansion and weighting functions is used in a Galerkin solution. Post currents are expressed as a Fourier series. As many Fourier series terms (e/sup jn Theta/) as desired may be included. All higher order (cutoff) mode interactions between posts are taken into account. The solution is rapid and accurate, and errors maybe controlled (specified). Data are given for the triple-post obstacle and for a two-element filter.

The Finite Difference Solution of Microwave Circuit Problems

Using finite difference methods this paper shows how solutions may be obtained with the aid of a digital machine to a wide range of microwave circuit problems. These problems include the parameters of TEM-mode transrnission lines, the equivalent circuits of obstacles in these lines, the cutoff frequencies of the fundamental mode in a waveguide of very general cross section, and the equivalent circuits of obstacles in rectangular waveguide. Methods for deriving the appropriate finite difference equations are presented and optimum methods for their solution set out; singularities are also included in the treatment. The paper ends with a resume of some typical results to problems of practical interest which have been obtained by these methods.

Perturbation Theorems for Waveguide Junctions, with Applications

Perturbation theorems are derived in the context of a theory of waveguide junctions. These theorems express changes in impedance or admittance matrix elements, due to changes in a waveguide junction, in terms of integrals over products of perturbed and unperturbed basis fields associated with the junction and with its adjoint. Media involved are required only to be linear. Concepts of first-order perturbation theory are discussed briefly, and the term "correct to the lowest order" is precisely defined. The need of explicit theorems telling when one may expect results actually correct to the lowest order is noted. Two problems are solved approximately by the perturbation approach: i) reflection at the junction of rectangular waveguide with filleted waveguide of the same main dimensions; and 2) the effect of finite conductivity of both obstacle and waveguide wall for half-round inductive obstacles in rectangular waveguide.

Half-round inductive obstacles in rectangular waveguide

Half-round inductive obstacles in rectangular waveguide