P. Kowalczyk

Gdansk University of Technology, Gdańsk, Pomeranian Voivodeship, Poland

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Publications (19)16.07 Total impact

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    ABSTRACT: This paper reviews research of Ruediger Vahldieck's group and the group at the Gdansk University of Technology in the area of model order reduction techniques for accelerating full-wave simulations. The applications of reduced order models to filter design as well as of local and nested (multilevel) macromodels for solving 3D wave equations and wave-guiding problems using finite difference and finite element methods are discussed.
    01/2012;
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    P Kowalczyk, L Kulas, M Mrozowski
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    ABSTRACT: In this paper a new technique for numerical analysis of microstructured optical fibers is proposed. The technique uses a combination of model order reduction method and discrete function expansion technique. A significant reduction of the problem size is achieved (by about 85%), which results in much faster simulations (up to 16 times) without affecting the accuracy.
    Optics Express 09/2011; 19(20):19354-64. · 3.55 Impact Factor
  • L. Kulas, P. Kowalczyk, M. Mrozowski
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    ABSTRACT: A new modal algorithm for fast frequency or time domain simulation of waveguide components and resonators is proposed. The new algorithm is based on the finite difference frequency domain method combined with domain decomposition, model order reduction and the projection of fields at domain boundaries on a modal basis. As a result, one converts Maxwell's equations into a very compact set of linear equations which can be solved extremely fast, at least two orders of magnitude faster than with previous algorithms and whose coefficient matrix is independent of frequency.
    IEEE Microwave and Wireless Components Letters 02/2011; · 1.78 Impact Factor
  • J.J. Michalski, P. Kowalczyk
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    ABSTRACT: This paper presents a novel method that is very efficient in solving multidimensional real and complex eigenvalue problems, commonly employed in electromagnetic analysis, which can be transformed into a nonlinear equation. The concept is realized as root tracing process of a real or complex function of N variables in the constrained space. We assume that the roots of the continuous function of N variables lie on the continuous (N-1) -dimensional hyperplane. The method uses regular N and (N-1)-Simplexes, at which vertices the considered function changes its sign. Based on (N-1)-Simplex, the function is evaluated at two new points that are vertices of new regular N-Simplexes for which (N-1)-Simplex is one of its (N-1)-faces. The algorithm, with the usage of stack, runs in an iterative mode tracing the roots inside the volume of the considered simplexes. As a result, the algorithm creates a chain of simplexes in the constrained region. The proposed algorithm is optimal in the sense of the number of function evaluations. The numerical results, real and complex dispersion characteristics of chosen microwave guides, have proven the versatility and efficiency of the proposed algorithm.
    IEEE Transactions on Microwave Theory and Techniques 01/2011; 59(9):2197-2205. · 2.23 Impact Factor
  • Piotr Kowalczyk, Lukasz Kulas, Michal Mrozowski
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    ABSTRACT: In this article the Legendre polynomials have been used to interpolate the field at the boundary of the meshes of different densities. The numerical verification of the proposed technique has been carried out in frequency domain. It has been shown that the accuracy of the presented method is very high and stable - the error monotonically decreases as a function of the refinement factor.
    01/2010;
  • P. Kowalczyk, M. Mrozowski
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    ABSTRACT: In this paper an accurate boundary condition is applied for analysis of open waveguiding structures properties. All types of modes are considered: guided, leaky and complex modes. The scheme is based on analytical solution obtained for homogeneous structure. The accuracy of the results is much better than in standard algorithm involving PML technique. The numerical tests show that the improvement is especially noticeable for imaginary part of the propagation coefficient which represents the radiation effects.
    Electromagnetic Theory (EMTS), 2010 URSI International Symposium on; 01/2010
  • A. Kusiek, P. Kowalczyk, J. Mazur
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    ABSTRACT: A new method of analysis of an arbitrary configuration of elliptical cylinders is presented. The treatment of such a problem is based on a combination of the cylindrical and elliptical coordinates systems. This approach is applied to the formulation of the scattered field at the surface of equivalent cylinder surrounding dielectric or metal elliptical object. To analyse the arbitrary set of elliptical cylinders, the iterative scattering procedure is used. A good agreement of the proposed method with the commercial FD simulator is achieved.
    IET Microwaves Antennas & Propagation 09/2008; · 0.84 Impact Factor
  • Adam Kusiek, Piotr Kowalczyk, Jerzy Mazur
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    ABSTRACT: An alternative method of analysis of elliptical post is presented. The method is based on a combination of elliptical and cylindrical coordinate systems. Proposed technique concerns single object only, however it can be easily extended to analysis of any set of the obstacles. To show the validity of the method three different kinds of resonators were examined. The results show a good agreement with analytical technique and FDFD (finite-difference frequency-domain) method.
    Microwaves, Radar and Wireless Communications, 2008. MIKON 2008. 17th International Conference on; 06/2008
  • P Kowalczyk, M Mrozowski
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    ABSTRACT: A highly accurate radiation boundary condition for finite difference analysis of open waveguides is introduced. The boundary condition is applicable to the structures embedded in a homogeneous medium and fitted to the cross section of the structure. The numerical tests carried out for a few types of waveguides including microstructured fibers showed that the proposed approach improves the accuracy by about an order of magnitude in comparison with the PML technique and eliminates all its disadvantages.
    Optics Express 11/2007; 15(20):12605-18. · 3.55 Impact Factor
  • A. Kusiek, P. Kowalczyk, J. Mazur
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    ABSTRACT: In this paper the new technique of analysis of an arbitrary configuration of metallic elliptical objects is presented. The proposed method is based on T-matrix representation of elliptical object in cylindrical coordinates system. The total scattered field is computed with usage iterative scattering procedure (ISP). The numerical results are compared with once obtained from commercial software and a very good agreement was achieved.
    Radioelektronika, 2007. 17th International Conference; 05/2007
  • M. Liskin, P. Kowalczyk, M. Mrozowski
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    ABSTRACT: In this paper we investigate the performance of perfectly matched layer technique. The obtained results are in a good agreement with the theoretical values for phase constant, however the method poorly models the radiation effects. As a result the error in imaginary part of the propagation constant can be as high as 10%.
    01/2007;
  • Rafal Lech, Piotr Kowalczyk, Jerzy Mazur
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    ABSTRACT: This paper presents the analysis of electromagnetic field scattering by a set of cylindrical objects made of pseudochiral material located in rectangular waveguide junctions and free space. Presented approach is based on the iterative scattering procedure (ISP) and the orthogonal expansion method. Several numerical examples for open and closed problems were presented. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1876–1880, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21797
    Microwave and Optical Technology Letters 06/2006; 48(9):1876 - 1880. · 0.59 Impact Factor
  • P Kowalczyk, M Wiktor, M Mrozowski
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    ABSTRACT: A new technique of numerical analysis of microstructured optical fibers is presented. The technique combines a standard 2D finite difference equations with the discrete function expansion. By doing this one gets a matrix eigenvalue problem of a smaller size and a simple formulation of radiation boundary condition. The new algorithm was tested for the microstructures of different types and excellent agreement of the obtained results with other methods was achieved.
    Optics Express 01/2006; 13(25):10349-59. · 3.55 Impact Factor
  • Michal Wiktor, Piotr Kowalczyk, Michal Mrozowski
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    ABSTRACT: A simple technique of numerical analysis of open resonator is presented. The technique combines a standard Finite Difference method with the Partial Eigenfunction Expansion. By doing this one gets a simple formulation of radiation boundary condition. The algorithm was tested for the dielectric resonator of different height placed in infinite radial waveguide and excellent agreement of the obtained results with other methods was achieved.
    01/2006;
  • Rafal Lech, Piotr Kowalczyk, Jerzy Mazur
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    ABSTRACT: This paper presents the analysis of electromagnetic field scattering by a set of cylindrical objects made of pseudochiral material located in rectangular waveguide junctions and free space. Presented approach is based on the Iterative Scattering Procedure (ISP) and the orthogonal expansion method. Several numerical examples for open and closed problems were presented.
    01/2006;
  • Piotr Kowalczyk, Michal Mrozowski
    04/2005; , ISBN: 9780471654506
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    P. Kowalczyk, M. Mrozowski
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    ABSTRACT: Recently, a radial basis functions (RBFs) method, which was originally proposed for interpolation problems, has been developed and applied to solve partial differential equations and eigenproblems. Properties of that method (mesh-free algorithm) allows one to use it in many areas, including electromagnetics. In this paper the mesh-free RBF method for solving Helmholtz equation was applied and a new adaptive algorithm for defining the set of interpolation centers was proposed. Using the proposed approach the cutoff wavelengths and the field distribution in cylindrical waveguides of arbitrary cross-section were calculated with a high accuracy.
    Microwaves, Radar and Wireless Communications, 2004. MIKON-2004. 15th International Conference on; 06/2004
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    ABSTRACT: The paper presents a selection of techniques that are currently being investigated at the Technical University of Gdansk and can be used to accelerate CAD of microwave circuits and the computation of high and low frequency electromagnetic fields. Techniques for creating surrogate CAD models and their application to automated design of band pass filters are discussed. Different strategies of electromagnetic field representation for mesh based and meshless methods are introduced and their efficiency illustrated on examples involving structures with complex geometries.
    Microwaves, Radar and Wireless Communications, 2004. MIKON-2004. 15th International Conference on; 06/2004
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    W Marynowski, P Kowalczyk, J Mazur
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    ABSTRACT: In this paper the definition of characteristic impedance for lossless microstrip and coplanar lines has been considered. It has been shown that due to a significant value of the displacement current related to longitudinal component of the electric field, impedance definition becomes ambiguous. Such ambiguity can cause considerable errors in design procedure. This effect is especially noticeable in the coplanar lines, in opposite to microstrip ones. To confirm the validity of the applied algorithm (spectral domain approach) the propagation coefficients and characteristic impedances have been compared to values obtained from commercial software.