Francisco Javier Pérez Soler

A Novel Efficient Technique for the Calculation of the Green's Functions in Rectangular Waveguides Based on Accelerated Series Decomposition

A new efficient technique for computing the Greens functions inside rectangular waveguides is presented. After a summary of the classical approaches and their difficulties, a new strategy is proposed, based on the decomposition of the main spectral series into simpler terms. Although the resulting series present better convergence rate, several acceleration techniques are combined to further improve the efficiency. Several results are presented to demonstrate the improvements in convergence rates obtained using the new decomposition.

Design of Bandpass Elliptic Filters Employing Inductive Windows and Dielectric Objects

In this paper, we propose an alternative configuration for the design of bandpass inductive filters using transversal topologies. The structure is based on the use of a dielectric post asymmetrically placed on a cavity resonator. The input and output windows will couple energy to the TE102-and TE103 -mode resonators at the same time, therefore obtaining the transversal topology. The proposed configuration is very compact, and allows to implement transmission zeros for maximum selectivity in an easy way. Results are validated with Ansofts finite-element High Frequency Structure Simulator tool, and with an integral-equation technique to demonstrate the validity of the proposed structure.

ANALYSIS OF INDUCTIVE WAVEGUIDE MICROWAVE COMPONENTS USING AN ALTERNATIVE PORT TREATMENT AND EFFICIENT FAST MULTIPOLE

This paper presents a simple and alternative approach for the analysis of inductive waveguide microwave components. The technique uses a surface integral equation formulation, in which the contours of the waveguide walls and of the inner obstacles are all discretized using triangular basis functions. In order to avoid the relative convergence problem of other techniques based on mode matching, an alternative port treatment is used. The technique is based on the application of the extinction theorem using the spatial representation of the Greens functions in the terminal waveguides. In addition, the Fast Multipole Method is proposed in order to reduce the computational cost for large problems. Different complex structures are analyzed, including microwave bandpass filters with elliptic transfer functions, waveguide bends and T-junctions. Results show the high accuracy and versatility of the technique derived.

FULL-WAVE ANALYSIS AND DESIGN OF BROADBAND TURNSTILE JUNCTIONS

The e-cient design of broadband turnstile junctions compensated with piled-up cylindrical metallic posts is discussed in this contribution. Very high relative bandwidths can be obtained, while maintaining the diameter of the input circular access port lower than the width of the rectangular waveguide ports, thus reducing the number of excited higher order circular waveguide modes. A novel full-wave analysis tool has also been implemented in order to reduce the CPU efiort related to the complete design process.

Comparison between the Kummer's transformation and Ewald method for the evaluation of the parallel plate Green's functions

In this paper, we present a convergence and efficiency study of two different acceleration techniques for the evaluation of the parallel plate Greens functions. The first technique is based on the extraction of the asymptotic terms of the spectral representation of the parallel plate Greens functions by applying the Kummers transformation. The second technique is a straightforward reformulation of the 2-D Greens functions for 1-D periodic structures to the parallel plate case. The PPW Greens functions calculated by the two methods have been successfully applied to the analysis of a practical inductive microwave filter containing metallic and dielectric posts. The filter analysis technique is based on solving a surface integral equation by the MoM. The convenience of using one of the proposed acceleration technique or the other for the evaluation of each Greens function components and its derivatives, necessary to solve the MoM problem, is properly justified

Analytical Evaluation of the Static MoM Terms for Volume and Surface Rectangular Domains

We present a simple analytical implementation of the static singular integrals arising in the volume/surface integral equation formulation for the analysis of mixed conducting and dielectric structures such as printed circuits with finite-size dielectric objects. The singularity of the Greens functions is extracted from the kernel of the integral equation as a static term. This term is then evaluated analytically for coincident rectangular cells in two and three dimensions. The new technique allows an accurate and efficient evaluation of method of moments (MoM) self-interactions compared to other methods previously used in the literature.

New efficient acceleration technique for the calculation of the Green’s functions in rectangular waveguides

In this paper, we have presented a new approach for the efficient calculation of the Greenpsilas functions inside a rectangular waveguide. The idea is to apply the Kummer transformation, using two static terms of the spectral domain Greenpsilas functions, obtained through a Taylor series expansion. Instead of applying the Ewald method to the whole series, it is only applied to the first static series. The other terms are accelerated via the summation by parts technique. We show that using the new strategy, the computational cost is considerably reduced as compared to a standard brute-force application of the Ewald method.

A simple simulation of 2D radomes using line source excitation and fast multipole method

Starting from a classical method of moments (MOM) approach for analyzing conducting surfaces coated with two layers of homogeneous media, we have replaced the usual plane wave excitation with line sources. In order to enhance the computational cost of this kind of problem, a decomposition based on the fast multipole method (FMM) has also been proposed. The value of the derived approach is that studies of possible effects of dielectric radomes on antennas can be performed. As a result, some practical effects of radomes on the radiation characteristics of antennas are identified and discussed.

2D surface formulation for conducting objects coated in multilayered homogeneous media using the fast multipole method

In this paper, the fast multipole method (FMM), one of the most important techniques developed in order to reduce the computational burden associated with the method of moments (MOM), is applied to analyze a 2D conducting body coated in a multilayered medium. A general formulation and some results are presented, which show the advantages of using the FMM in the solution of this kind of problem.