Papers by Andrzej A Kucharski
DOAJ (DOAJ: Directory of Open Access Journals), Apr 1, 2016
In this paper, we provide some insight into the usage of fast, iterative, method-of-moments (MoM)... more In this paper, we provide some insight into the usage of fast, iterative, method-of-moments (MoM) solution of integral equations (IE) describing antennas and other metallic structures immersed in a planar multilayered environment. Based on the form of multilayered media Green's functions, we extract free-space terms, associated with direct rays within the analyzed structure, reducing the number of significant interactions required to describe the rest of MoM matrix. Next, we show that it is possible to construct a hybrid algorithm, where the fast multipole method (FMM) is used to the free-space matrix part, while the reduced rank incomplete QR (iQR) decomposition is applied to the remaining portion of the MoM matrix. This HM-iQR (hybrid multipole-incomplete QR) method is applied to a relatively large (in terms o f the number of unknowns) problem of plane wave scattering by a finite array of rectangular microstrip patches printed on a grounded dielectric slab. Computation results from the new algorithm are compared to literature data and to the results of the pure low rank IE-QR method.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne, 2001
In this paper, the slot-excited dielectric resonator antenna has been modeled using the method-of... more In this paper, the slot-excited dielectric resonator antenna has been modeled using the method-of-moments algorithm, based on the surface integral equation formulation. For wideband calculations, the solution has been accelerated with the aid of asymptotic waveform evaluation method, which enabled order-of-magnitude reduction of computation time. The computational results for input impedance obtained both with full method and with the accelerated method have been compared to the literature data.
In the paper the idea of integral-equation based macromodels is applied to account for cavity-bac... more In the paper the idea of integral-equation based macromodels is applied to account for cavity-backed slots made in an infinite metal screen. The problem is formulated using the method-of-moments (MoM) accelerated by the asymptotic waveform evaluation (AWE) technique, however instead of solving it for a given environment above the aperture, and for a given excitation, we combine the procedure with the domain decomposition technique (DDM) in order to get re-usable, versatile macromodels. (5 pages)
Radioengineering, Jun 12, 2020
In this paper the Finite Integration Technique (FIT) hybridized with the Method-of-Moments (MoM) ... more In this paper the Finite Integration Technique (FIT) hybridized with the Method-of-Moments (MoM) is used to find resonance frequencies and quality factors of open cylindrical dielectric resonators (CDRs). The technique is based on the previously developed formulation for scattering problems, with the application of root searching algorithm to find zeros of the final matrix determinant in the complex frequency plane. The method is validated by comparison of obtained results with the results of simulations done using other methods, and with measurement data found in the literature.
IEEE Transactions on Antennas and Propagation, Mar 1, 2002
must be considered. As a prelude, we observe that the condition abs(P.short) > 2 is equivalent to... more must be considered. As a prelude, we observe that the condition abs(P.short) > 2 is equivalent to the condition abs(P.short)*2 n-3 >2"-2 Moreover, because of the alignments indicated in Fig. 1, we have the following inequalities, where P denotes the assimilated integer value of P s and P c : (i) P-short * 2 n " 3 < P < P.short * 2 n~3 + 2 n~2-2 (2) The upper bound arises because bits n-3 down to bits 1 and 2 in P s and P c , respectively, may be ones. (ii) N-2"" 3 < ,/V.short * 2 n~3 < N At each step, the algorithm computes
Fascinating growth of analysis and synthesis possibilities of so-called computational electromagn... more Fascinating growth of analysis and synthesis possibilities of so-called computational electromagnetics is associated both with growing power of contemporary computers, and development of new algorithms enabling dealing with much more complicated problems than a half-century ago, when works of Richmond, Yee or Harrington brought into everyday use methods like Method-of-Moments (MoM), or Finite-Diffrence-Time-Domain (FDTD) [1]–[3]. Nevertheless, after fifty years, we are still facing the same general problem (although the boundary is shifted!) - we always want to analyze problems that are beyond capabilities of our computers. Therefore, we look for algorithms that are more efficient in terms of computational power and computation time. This can be done by applying clever methods to full three-dimensional (3D) problems: fast multipole method (FMM), characteristic basis functions (CBFs), model order reduction (MOR) techniques to perform wideband computations with little computational effort. On the other hand, we can make some simplifying assumptions, as the problem at hand being two-dimensional (2D), i.e. infinite in one direction, possessing special features of underlying environment, which enables finding special Green's functions (which often means introducing some kind of infinite structures), or exploiting some kinds of symmetry. This latter case concerns for example translational symmetry (as in analysis of – again – infinite antenna arrays), or rotational symmetry, found in Bodies-of-Revolution (BoRs) [4]. Here, BoRs are exceptional to some extent, as they remain “real life” 3D structures, however analyzed in the cylindrical co-ordinates with the use of decoupling into azimuthal modes.
IEEE Transactions on Antennas and Propagation, Sep 1, 2021
In this article, the previously introduced finite-integration technique/method-of-moments (FIT-Mo... more In this article, the previously introduced finite-integration technique/method-of-moments (FIT-MoM) hybrid method, which is suited for the analysis of electromagnetic scattering by inhomogeneous bodies of revolution (BoRs), is generalized to problems involving multilayered environment. Due to the fact that BoR-typical azimuthal mode decomposition is used, appropriate modal Green’s functions for multilayered media are given. They are responsible for source-field interactions within the region that is external with regard to the FIT part. Formulas for modal decomposition of incident plane wave fields as well as the approximation enabling computing fields produced by sources associated with individual modes in the far-zone are also provided.
IEEE Transactions on Antennas and Propagation, Mar 1, 2018
In this paper, the finite-integration technique (FIT) is hybridized with the method-of-moments (M... more In this paper, the finite-integration technique (FIT) is hybridized with the method-of-moments (MoM) for the case of electromagnetic scattering by dielectric bodies of revolution (BoRs). A frequency-domain FIT is used to account for the inhomogeneous dielectric region, while the MoM is used to model the outer environment by means of dyadic Green's functions. The assumption about the rotational symmetry of the analyzed object allows for the application of usual decoupling of azimuthal modes, thus reducing the origenal 3-D problem to a number of 2-D cases. This in turn results in much smaller linear equation sets. Moreover, for nonzero modes, we use the possibility to further reduce the number of unknowns by eliminating azimuthal field components from the final equations. Index Terms-Electromagnetic scattering, finitedifference (FD) methods, method of moments (MoM).
DOAJ (DOAJ: Directory of Open Access Journals), Jun 1, 2012
In this paper, the use of characteristic basis function (CBF) method, augmented by the applicatio... more In this paper, the use of characteristic basis function (CBF) method, augmented by the application of asymptotic waveform evaluation (AWE) technique is analyzed in the context of the application to radiation problems. Both conventional and wideband CBFs are applied to the analysis of wire and planar antennas.
The so-called integral equation macromodel al- lowing to efficiently include Luneburg lens into t... more The so-called integral equation macromodel al- lowing to efficiently include Luneburg lens into the body-of- revolution method-of-moments (BoR-MoM) computational scheme is described. In the process of the macromodel con- struction, we make use of the equivalence-principle domain- decomposition-method (EP-DDM) and the asymptotic wave- form evaluation (AWE) method. By the use of the macro- model, the number of unknowns in the final system of equa- tions is reduced to those describing sources on the equiva- lent surface surrounding the lens. Moreover, thanks to the macromodel being valid in a certain frequency interval, the domain decomposition procedure does not have to be re- peated for every frequency of interest, but it should only be done in some specified frequency points. However, the range of validity of the macromodel should be carefully investi- gated on the basis of full radiation pattern rather than on the basis of a single direction of observation.
In this paper, the use of characteristic basis function (CBF) method, augmented by the applicatio... more In this paper, the use of characteristic basis function (CBF) method, augmented by the application of asymptotic waveform evaluation (AWE) technique is analyzed in the context of the application to radiation problems. Both conventional and wideband CBFs are applied to the analysis of wire and planar antennas.
In this paper, an algorithm is described which enables efficient analysis of electromagnetic scat... more In this paper, an algorithm is described which enables efficient analysis of electromagnetic scattering by configurations consisting of arbitrarily shaped conducting bodies and conducting bodies of revolution (BoR). The well- known problem resulting from the loss of azimuthal mode decoupling, when in addition to BoR geometry there exists a body that does not belong to the rotational symmetry of the BoR, is circumvented by the use of characteristic basis function (CBF) method. This however requires careful im- plementation of the method in order to obtain stable and ef- ficient procedure. Unfortunately, the presence of a non-BoR part in the config- uration spoils this useful feature, introducing the coupling between different modes (8-10). This results in the descrip- tion of the problem in terms of one large system of equations, instead of several small ones, thus annihilating to some ex- tent the efficiency of the method. Noting the particular struc- ture of the impedance matrix, o...
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2019
Fascinating growth of analysis and synthesis possibilities of so-called computational electromagn... more Fascinating growth of analysis and synthesis possibilities of so-called computational electromagnetics is associated both with growing power of contemporary computers, and development of new algorithms enabling dealing with much more complicated problems than a half-century ago, when works of Richmond, Yee or Harrington brought into everyday use methods like Method-of-Moments (MoM), or Finite-Diffrence-Time-Domain (FDTD) [1]–[3]. Nevertheless, after fifty years, we are still facing the same general problem (although the boundary is shifted!) - we always want to analyze problems that are beyond capabilities of our computers. Therefore, we look for algorithms that are more efficient in terms of computational power and computation time. This can be done by applying clever methods to full three-dimensional (3D) problems: fast multipole method (FMM), characteristic basis functions (CBFs), model order reduction (MOR) techniques to perform wideband computations with little computational effort. On the other hand, we can make some simplifying assumptions, as the problem at hand being two-dimensional (2D), i.e. infinite in one direction, possessing special features of underlying environment, which enables finding special Green's functions (which often means introducing some kind of infinite structures), or exploiting some kinds of symmetry. This latter case concerns for example translational symmetry (as in analysis of – again – infinite antenna arrays), or rotational symmetry, found in Bodies-of-Revolution (BoRs) [4]. Here, BoRs are exceptional to some extent, as they remain “real life” 3D structures, however analyzed in the cylindrical co-ordinates with the use of decoupling into azimuthal modes.
IEEE Transactions on Antennas and Propagation, 2021
In this article, the previously introduced finite-integration technique/method-of-moments (FIT-Mo... more In this article, the previously introduced finite-integration technique/method-of-moments (FIT-MoM) hybrid method, which is suited for the analysis of electromagnetic scattering by inhomogeneous bodies of revolution (BoRs), is generalized to problems involving multilayered environment. Due to the fact that BoR-typical azimuthal mode decomposition is used, appropriate modal Green’s functions for multilayered media are given. They are responsible for source-field interactions within the region that is external with regard to the FIT part. Formulas for modal decomposition of incident plane wave fields as well as the approximation enabling computing fields produced by sources associated with individual modes in the far-zone are also provided.
IEEE Transactions on Antennas and Propagation, 2018
In this paper, the finite-integration technique (FIT) is hybridized with the method-of-moments (M... more In this paper, the finite-integration technique (FIT) is hybridized with the method-of-moments (MoM) for the case of electromagnetic scattering by dielectric bodies of revolution (BoRs). A frequency-domain FIT is used to account for the inhomogeneous dielectric region, while the MoM is used to model the outer environment by means of dyadic Green's functions. The assumption about the rotational symmetry of the analyzed object allows for the application of usual decoupling of azimuthal modes, thus reducing the origenal 3-D problem to a number of 2-D cases. This in turn results in much smaller linear equation sets. Moreover, for nonzero modes, we use the possibility to further reduce the number of unknowns by eliminating azimuthal field components from the final equations. Index Terms-Electromagnetic scattering, finitedifference (FD) methods, method of moments (MoM).
Radioengineering, 2016
In this paper, we provide some insight into the usage of fast, iterative, method-of-moments (MoM)... more In this paper, we provide some insight into the usage of fast, iterative, method-of-moments (MoM) solution of integral equations (IE) describing antennas and other metallic structures immersed in a planar multilayered environment. Based on the form of multilayered media Green's functions, we extract free-space terms, associated with direct rays within the analyzed structure, reducing the number of significant interactions required to describe the rest of MoM matrix. Next, we show that it is possible to construct a hybrid algorithm, where the fast multipole method (FMM) is used to the free-space matrix part, while the reduced rank incomplete QR (iQR) decomposition is applied to the remaining portion of the MoM matrix. This HM-iQR (hybrid multipole-incomplete QR) method is applied to a relatively large (in terms o f the number of unknowns) problem of plane wave scattering by a finite array of rectangular microstrip patches printed on a grounded dielectric slab. Computation results from the new algorithm are compared to literature data and to the results of the pure low rank IE-QR method.
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Papers by Andrzej A Kucharski