Papers by Hristos Anastassiu
2023 12th International Conference on Modern Circuits and Systems Technologies (MOCAST)
2022 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom)
Technologies
A very large number of scientific papers have been published in the literature on wearable antenn... more A very large number of scientific papers have been published in the literature on wearable antennas of several types, structure and functionality. The main focus is always antenna efficiency from an engineering point of view. However, antenna integration into actual, realistic garments is seldom addressed. In this paper, 2D pattern and 3D virtual prototyping technology is utilized to develop regular clothing, available in the market, in which wearable antennas are incorporated in an automated manner, reducing the chances of compromising the garment elegance or comfort. The functionality of various commercial software modules is described, and particular design examples are implemented, proving the efficiency of the procedure and leading the way for more complex configurations.
The Physical Optics approximation is employed in the derivation of a closed form expression for t... more The Physical Optics approximation is employed in the derivation of a closed form expression for the Radar Cross Section (RCS) of a flat, polygonal, perfectly conducting (PEC) plate, located over a dielectric, possibly lossy half space. The well-known "fourpath model" is invoked in a first order approximation of the half space contribution to the scattering mechanisms. Numerical results are successfully compared to a reference, Moment Method solution. The analytical expressions derived can facilitate very fast RCS calculations for realistic scatterers, such as ships in a sea environment, or aircraft flying low over the ground. INTRODUCTION Radar Cross Section (RCS) estimation of electrically large, complex targets is usually performed via high frequency techniques, such as Physical Optics (PO). A target of complex geometry is routinely decomposed into an aggregate of elementary surfaces, and the total scattered field is computed as a superposition of the elementary scatteri...
Applied Sciences, 2020
The method of auxiliary sources (MAS) is utilized in the analysis of Transverse Magnetic (TM) pla... more The method of auxiliary sources (MAS) is utilized in the analysis of Transverse Magnetic (TM) plane wave scattering from infinite, conducting, or dielectric cylinders, including curved wedges. The latter are defined as intersections of circular arcs. The artificial surface, including the auxiliary sources, is shaped in various patterns to study the effect of its form on the MAS accuracy. In juxtaposition with the standard, conformal shape, several deformations are tested, where the auxiliary sources are forced to approach the tip of the wedge. It is shown that such a procedure significantly improves the accuracy of the numerical results. Comparisons of schemes are presented, and the optimal auxiliary source location is proposed.
In this paper a numerical analysis of electromagnetic scattering from various infinite, dielectri... more In this paper a numerical analysis of electromagnetic scattering from various infinite, dielectric cylindrical objects is presented using the Method of Auxiliary Sources (MAS). Several cross sections which can be considered as perturbed duplicates of the circle were investigated. The computational error associated with the numerical solution of the MAS linear system, as well as the condition number of the pertinent impedance matrix are plotted and the results are discussed. Furthermore, a parametric analysis is conducted in order to examine the effect of various parameters on the accuracy of the solution and the stability of the linear system. The aim of this study is the extraction of useful conclusions on the optimum location of the auxiliary sources for arbitrarily shaped dielectric scatterers.
2003 IEEE International Symposium on Electromagnetic Compatibility, 2003. EMC '03., 2003
Page 1. I Accuracy Analysis of the Method of Auxiliary Sources (MAS); for Scattering by a Perfect... more Page 1. I Accuracy Analysis of the Method of Auxiliary Sources (MAS); for Scattering by a Perfectly Conducting Cylinder Hristos T. Anastassiu Institute of Communications and Computer Systems, National Technical University ...
2000 10th Mediterranean Electrotechnical Conference. Information Technology and Electrotechnology for the Mediterranean Countries. Proceedings. MeleCon 2000 (Cat. No.00CH37099)
Page 1. The P(MMAS) Interactive Environment: An Internet Service Coupling Web Technology and HPCN... more Page 1. The P(MMAS) Interactive Environment: An Internet Service Coupling Web Technology and HPCN to Analyse Conformal Microstrip Arrays Andy Marsh, Dimitra I. Kaklamani, Member, IEEE, Hristos T. Anastassiu, Member, IEEE, and Phridon Shubitidze ...
2006 First European Conference on Antennas and Propagation, 2006
Two versions of a preconditioning procedure are described for a class of two-dimensional scatteri... more Two versions of a preconditioning procedure are described for a class of two-dimensional scattering problems, when the latter are solved via the Method of Auxiliary Sources (MAS). The method is useful for the case of shrinking auxiliary surfaces, i.e. when the linear system may become ill-conditioned. If the cross sectional boundary can be regarded as a deformation of a circle,
Progress In Electromagnetics Research, 2005
IEEE Transactions on Antennas and Propagation, 2002
... Hristos T. Anastassiu, Member, IEEE, Dimitra I. Kaklamani, Member, IEEE, Dimitrios P. Economo... more ... Hristos T. Anastassiu, Member, IEEE, Dimitra I. Kaklamani, Member, IEEE, Dimitrios P. Economou, and Olav Breinbjerg, Member, IEEE ... investigated above, RCS convergence was generally achieved with a minimum auxiliary source den-sity equal to 5 per wavelength. ...
IEEE Transactions on Antennas and Propagation, 2010
IEEE Transactions on Antennas and Propagation, 2004
IEEE Transactions on Antennas and Propagation, 2008
Fundamental properties of certain popular integral equations for thin-wire circular-loop antennas... more Fundamental properties of certain popular integral equations for thin-wire circular-loop antennas with nonsingular kernels are studied. The cornerstone of our study is a large-asymptotic formula for the n'th Fourier coefficient of the nonsingular kernel. Four different methods of driving the circular loop are considered; namely, the delta-function generator, the finite-gap generator, a certain type of frill generator, and the case
IEEE Transactions on Antennas and Propagation, 2004
... of Auxiliary Sources (MAS) for Scattering by a Circular Cylinder Hristos T. Anastassiu, Membe... more ... of Auxiliary Sources (MAS) for Scattering by a Circular Cylinder Hristos T. Anastassiu, Member, IEEE, Dimitrios G. Lymperopoulos, and Dimitra I. Kaklamani, Member, IEEE ... Dimitrios G.Lymperopoulos was born in Athens, Greece, on December 8, 1978. ...
IEEE Transactions on Antennas and Propagation, 2010
ABSTRACT Errors were identified in the above titled paper (ibid., vol. 56, no. 1, pp. 151-157, Ja... more ABSTRACT Errors were identified in the above titled paper (ibid., vol. 56, no. 1, pp. 151-157, Jan. 08), including several numerical errors on Table I. The errors do not affect the discussions. Corrections are presented here.
IEEE Antennas and Propagation Magazine, 2002
IEEE Antennas and Propagation Magazine, 2003
Electrical Engineering, 2006
ABSTRACT The analytic inversion of the Method of Auxiliary Sources (MAS) matrix plays an importan... more ABSTRACT The analytic inversion of the Method of Auxiliary Sources (MAS) matrix plays an important role in the rigorous investigation of the accuracy of the method. In this paper we investigate the accuracy of MAS when the method is applied to plane wave scattering under oblique incidence by an infinite, dielectric circular cylinder. For this scattering configuration, we prove that the MAS matrix is analytically invertible and hence obtain a concrete expression for the discretization error. A basic contribution of this paper lies in the analytic determination of the auxiliary sources’ locations, for which the corresponding system’s matrix becomes singular. Furthermore, we calculate the computational error resulting from numerical matrix inversion, and compare it to the analytical error. The dependence of both types of errors on the angle of incidence and on the dielectric permittivity is investigated. Finally, error minimization indicates the auxiliary sources’ optimal location.
Recent advances in the field of computational electromagnetics, as well as the increasing availab... more Recent advances in the field of computational electromagnetics, as well as the increasing availability of processing power in computer systems, have enabled the analysis of complex antennas, which are often used in wireless and personal communications. Modern CAD tools permit the rapid analysis of such antenna systems and the visualization of their radiation characteristics. The ability to visualize two- and three-dimensional radiation patterns is a key to the understanding of basic antenna principles. Therefore, the study of the electromagnetic fields and their interaction with antennas therefore benefits tremendously by the introduction of advanced visualization tools. Additionally, current Web technologies provide unprecedented opportunities for making antenna analysis and design software packages accessible through standard browsers, removing often complicated interfaces. This article describes an integrated, World-Wide-Web-based asynchronous simulation environment for analyzing conformal microstrip antenna arrays. By coupling Web technology with visualization languages that offer interactivity and are suited to a web environment, such as the Virtual Reality Modelling Language (VRML), we can achieve the development of realistic visualization applications that offer a number of unique features over traditional visualization techniques.
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Papers by Hristos Anastassiu