M. Taroncher

Compact CPW-Fed Combline Filter in Substrate Integrated Waveguide Technology

In this letter, the design and experimental results of compact low loss combline filters, based on the extension of the classical coaxial waveguide resonator to Substrate Integrated Waveguide (SIW) technology, are succesfully demonstrated. A three-pole 5% FBW Chebyshev filter has been designed, fabricated and measured. The fabricated device shows an excellent agreement with simulated results. These structures keep the low-cost fabrication scheme of single-layer PCB processing, while requiring less than half the area compared to a conventional SIW design.

CAD of complex passive devices composed of arbitrarily shaped waveguides using Nystro/spl uml/m and BI-RME methods

In this paper, a novel computer-aided design (CAD) tool of complex passive microwave devices in waveguide technology is proposed. Such a tool is based on a very efficient integral-equation analysis technique that provides a full-wave characterization of discontinuities between arbitrarily shaped waveguides defined by linear, circular, and/or elliptical arcs. For solving the modal analysis of such arbitrary waveguides, a modified version of the well-known boundary integral-resonant-mode expansion (BI-RME) method using the Nystro/spl uml/m approach, instead of the traditional Galerkin version of the method of moments, is proposed, thus providing significant savings on computational costs and implementation complexity. The novel theoretical aspects of this Nystro/spl uml/m approach, as well as their impact on the original BI-RME formulation, are fully described. Comparative benchmarks between this new technique and the classical BI-RME formulation using Galerkin are successfully presented for the full-wave analysis of frequently used irises (i.e., rectangular cross-shaped and circular multiridged) and for the CAD of complex waveguide components (such as rectangular waveguide filters considering mechanization effects and dual-mode circular waveguide filters with elliptical irises).

Accurate consideration of metal losses in planar waveguide junctions using an efficient integral equation technique

Metal losses in passive waveguide devices are more pronounced and hazardous at higher frequencies. In this paper, we propose a very efficient integral equation technique for the accurate consideration of losses in the metal walls of any planar waveguide junction. For verification purposes, the results provided by the novel theory are successfully compared with those obtained with a lower efficiency commercial software. Combining this novel technique with a perturbation method that includes propagation losses, we have been able to predict all the losses effects in a 4-pole coupled cavities filter.

Multipactor Effect Analysis and Design Rules for Wedge-Shaped Hollow Waveguides

A numerical model for predicting the multipactor breakdown effect in wedge-shaped hollow waveguides is presented in this paper. The computation of electromagnetic fields is based on the boundary integral-resonant mode expansion method, which provides the modal chart of hollow waveguides with any arbitrary cross section. The advantage of using wedge-shaped waveguides with respect to conventional rectangular ones is the deviation of the resonant paths of the electrons toward regions with lower voltages, thus reducing the probability of multipactor threshold for certain input power. To validate this method, our results have been compared with simulations from previous theoretical studies. Once the simulation tool is validated, it is used to predict the multipactor threshold of wedge-shaped waveguides with different symmetric inclination angles of their horizontal plates. Finally, susceptibility curves as the ones already available for rectangular waveguides are presented. These charts are useful for designing innovative waveguide geometries with improved multipactor-free working power ranges.

Analysis of the electromagnetic radiation generated by a multipactor discharge occurring within a microwave passive component

Multipactoring is a non-linear phenomenon that appears in high-power microwave equipment operating under vacuum conditions and causes several undesirable effects. In this paper, a theoretical and experimental study of the RF spectrum radiated by a multipactor discharge, occurring within a realistic microwave component based on rectangular waveguides, is reported. The electromagnetic coupling of a multipactor current to the fundamental propagative mode of a uniform waveguide has been analysed in the context of the microwave network theory. The discharge produced under a single-carrier RF voltage regime has been approached as a shunt current source exciting such a mode in a transmission-line gap region. By means of a simple equivalent circuit, this model allows prediction of the harmonics generated by the discharge occurring in a realistic passive waveguide component. Power spectrum radiated by a third-order multipactor discharge has been measured in an E-plane silver-plated waveguide transformer, thus validating qualitatively the presented theory to simulate the noise generated by a single-carrier multipactor discharge.

Efficient full-wave modal analysis of arbitrarily shaped waveguides using BI-RME and Nystrom methods

This paper describes a novel technique for the very efficient and accurate full-wave modal analysis of cylindrical waveguides with arbitrary cross-section. This new technique relies on solving the integral equations that provide the well-known Boundary Integral - Resonant Mode Expansion (BI-RME) method by the Nyström approach, instead of using the traditional Galerkin version of the Method of Moments (MoM), thus providing large savings on computational costs. Accuracy aspects of this simple and fast procedure, which are directly connected to the rigorous treatment of the singular behaviour of the integral equation kernels, are carefully considered for waveguides defined by straight, circular and/or elliptical arcs. Comparative benchmarks between the new technique and the original BI-RME method are successfully presented for single- and multi-ridged waveguides, elliptical waveguides and rectangular waveguides with rounded corners.

Parallel Implementation in PC Clusters of a Lanczos-based Algorithm for an Electromagnetic Eigenvalue Problem

This paper describes a parallel implementation of a Lanczos-based method to solve generalised eigenvalue problems related to the modal computation of arbitrarily shaped waveguides. This efficient implementation is intended for execution in moderate-low cost workstations (2 to 4 processors). The problem under study has several features: the involved matrices are sparse with a certain structure, and all the eigenvalues needed are contained in a given interval. The novel parallel algorithms proposed show excellent speed-up for small number of processors

Efficient and Accurate Consideration of Ohmic Losses in Waveguide Diplexers and Multiplexers

The accurate consideration of all ohmic losses effects in waveguide manifold diplexers and multiplexers is rigorously studied in this paper. For such purposes, a full-wave CAD tool based exclusively on modal methods is originally proposed. Proceeding in this very efficient way, losses are precisely considered in all common components of such complex devices, i.e. planar junctions, uniform lines and multi-port circuits implemented in waveguide technology. For verification purposes, we have successfully compared our results for a magic-T junction and a manifold diplexer with experimental and numerical results

On the rigorous calculation of all ohmic losses in rectangular waveguide multi-port junctions

In this paper, all ohmic losses effects present in rectangular waveguide multi-port junctions are rigorous and efficiently computed. For this purpose, a new formulation based on the theory of cavities, which provides generalized admittance matrix representations for such junctions, is pro- posed. To validate this theory, we have successfully compared our results with numerical data of a lossy E-plane T-junction and of a hollow waveguide, as well as with experimental measurements of a real H-plane T-junction.

Full-Wave Analysis and Applications of EBG Waveguides Periodically Loaded with Metal Ridges

In this paper, a fast and accurate full-wave analysis tool of passive structures based on Electromagnetic-Bandgap (EBG) waveguides periodically loaded with metal ridges is proposed. For this purpose, a very efficient Integral Equation (IE) technique is followed to model the planar steps involving arbitrary waveguides. The well-known Boundary Integral - Resonant Mode Expansion (BI-RME) method is used to obtain the modal chart of the ridged waveguides. In order to show the advantages of this tool, a periodically loaded E-plane filter with improved stopband performance is analyzed and compared to standard implementation. Dispersion relations are also derived and used as guidelines for designing an EBG fifth-order low-pass filter.