Session 2P7 SC1: Novel Mathematical Methods in Electromagnetics

Session 2P7 SC1: Novel Mathematical Methods in Electromagnetics Axiomatics of the Blondel-Park Transformation Giovanni Franco Crosta, G. Chen,................................................................. 1024 Nonlinear Goubau Line: Numerical Study of TE-polarized Waves Eugene Yu. Smol kin, Yury V. Shestopalov,......................................................... 1025 Numerical Path-integration Computation of the Capacity and Electric Polarizability Tensor of Complexshaped Particles Jack F. Douglas,................................................................................... 1026 Unified Description of Chirped Gaussian Pulse Propagation of Arbitrary Initial Width in a Multiple Resonance Lorentz Medium Constantinos M. Balictsis,.......................................................................... 1027 Block LU Preconditioner for the Electric Field Integral Equation Stanislav L. Stavtsev,............................................................................... 1028 Permittivity Reconstruction of a Diaphragm in a Rectangular Waveguide: Unique Solvability of Benchmark Inverse Problems Yury V. Shestopalov, Yury G. Smirnov, Ekaterina D. Derevyanchuk,............................... 1029 The Application of Non-linear Dynamics Methods for Radar Target Identification Frederic J. Rachford, Thomas L. Carroll,........................................................... 1030 Verification of Computational Model of Transmission Coefficients of Waveguide Filters Pavel Tomasek, Yury V. Shestopalov,.............................................................. 1031 Computations Related to Nanoparticle Characterization and Nanocomposite Property Estimation Fernando Vargas-Lara, Jack F. Douglas,........................................................... 1032 Exponential Regularization of EM Dyadic Green s Functions via Green s Function-induced Dirac δ- functions Alireza R. Baghai-Wadji,........................................................................... 1033 Superresolution Based on the Methods of Extrapolation Boris A. Lagovsky, Alexander B. Samokhin, Yury V. Shestopalov,.................................. 1034 Analysis of Quasi-circular Polarization in Near Field of Smart Shelf RFID Antenna Radiation Andrey S. Andrenko,............................................................................... 1035 CICT: A Novel Framework for Biomedical and Bioengineering Application Rodolfo A. Fiorini,................................................................................. 1036 Multichannel Filter Banks and Their Implementation Using Computers with a Parallel Structure D. I. Kaplun, Dmitry M. Klionskiy, A. S. Voznesenskiy, V. V. Gulvanskiy,........................ 1037 Regularization of Ill-conditioned Numerical Scheme of an Analytical Formulation: Scattering by Circularly Layered Cylinders Emrah Sever, Fatih Dikmen, Farhad Mazlumi, Yury A. Tuchkin,.................................. 1038 1023

1024 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 Axiomatics of the Blondel-Park Transformation G. F. Crosta 1 and G. Chen 2 1 University of Milan Bicocca, Italy 2 Texas A & M University, USA Abstract The doubly-fed induction generator (DFIG) is a key constituent of energy conversion plants. The control of a DFIG is a challenge, whenever the primary energy supply (e.g., the wind velocity field) is characterised by intermittency. The mathematical model and control of a DFIG rely on the Blondel-Park transformation, which is known to simplify the governing equations. The distinctive feature of this contribution consists of showing how the Blondel- Park transformation derives from a set of conditions to be met by a group. Such a group is shown to exist and to continuously depend on one parameter. The uniqueness of its infinitesimal generator is also shown. As an application, the well-known electric torque theorem is proved in a simple way, which relies on a product of matrices formula. The latter, in turn, is a by-product of the axiomatic deduction of the Blondel-Park transformation.

Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 1025 Nonlinear Goubau Line: Numerical Study of TE-polarized Waves E. Yu. Smol kin 1 and Yu. V. Shestopalov 2 1 Penza State University, Russia 2 University of Gävle, Sweden Abstract A conducting cylinder covered by a concentric dielectric layer called the Goubau Line (GL) is the simplest type of open metal-dielectric waveguides. A complete mathematical investigation of the spectrum of symmetric surface modes in a GL is performed in [1]. Papers [2, 3] develop the theory of wave propagation in layered nonlinear dielectric waveguides. However, there are very few results concerning the analysis of wave propagation in a GL with an external concentric layer having variable, nonlinear, or variable and nonlinear permittivity. We aim this study to fill this gap and consider the problem of electromagnetic TE (transverse-electric) wave propagation in a GL with nonlinear permittivity ε = ε(ρ) + f( E 2 ) of the dielectric medium filling the GL layer (here ε(ρ) is a function of inhomogeneity which depends on the radius of the waveguide, f is a function that models nonlinearity, and E is the complex amplitude of the electric field). We consider only the intensity-dependent permittivity. The determination of TE waves is reduced to a nonlinear transmission eigenvalue problem for Maxwell s equations, which is then reduced to a system of nonlinear ordinary differential equations. Numerical experiments are carried out for two types of nonlinearities: ε = ε(ρ) + αu 2 (Kerr law) and ε = ε(ρ) + α(1 e βu2 ) (nonlinearity with saturation), where ε(ρ) = 1 ρ, const, or ρ. Comparison with linear homogeneous (inhomogeneous) and nonlinear homogeneous (inhomogeneous) cases are performed. Calculations are carried out for various frequency and parameter ranges. REFERENCES 1. Shestopalov, Y., E. Kuzmina, and A. Samokhin, On a mathematical theory of open metaldielectric waveguides, FERMAT, Vol. 5, 1 9, 2014. 2. Valovik, D. V., Y. G. Smirnov, and E. Yu. Smol kin, Nonlinear transmission eigenvalue problem describing TE wave propagation in two-layered cylindrical dielectric waveguides, Computational Mathematics and Mathematical Physics, Vol. 53, 1150 1161, 2013. 3. Valovik, D. V. and E. Yu. Smol kin, Calculation of the propagation constants of inhomogeneous nonlinear double-layer circular cylindrical waveguide by means of the Cauchy problem method, Journal of Communications Technology and Electronics, Vol. 58, 759 767, 2013.

1026 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 Numerical Path-integration Computation of the Capacity and Electric Polarizability Tensor of Complex-shaped Particles Jack F. Douglas Materials Science and Engineering Laboratory, NIST, Gaithersburg, MD 20879, USA Abstract Many boundary value problems arising in materials science modeling involve complicated boundary shapes and boundary data, making analytic solution based on conventional partial differential equation methods difficult. In particular, it is important to develop effective computational methods for calculating the electromagnetic and transport properties of nanoparticles for understanding their interaction with electromagnetic radiation to allow their manipulation with optical traps and separation with fields. These properties are also basic to characterizing particle and polymer geometry and interparticle interaction through solution property measurements. This class of problems is made challenging by the fact that large ensembles of objects having rather complex shape must be considered an ensemble averaged properties must be determined. As illustrative examples, we discuss specific systems such as carbon nanotubes and graphene, proteins, DNA and Au nanoparticles with grafted with DNA. These problems are daunting since there is still no accurate analytic theory for calculating basic transport properties (e.g., diffusion coefficient and intrinsic viscosity) and electromagnetic properties (capacity and polarizability) of even simple objects like a cube or stochastically defined objects such as random walk polymer chains modeling polymers in solution. In many cases, finite elements are also found to be intractable when the geometry shape becomes highly complex. As a step towards attacking this broad class of problems, we focus on the problem of calculating the self-capacity and electric polarizability tensor of conductive particles having essentially arbitrary geometry based a novel computational method involving path-integration. The basic concepts behind the method are described and the method validated in cases where exact analytic, or at least highly accurate numerical estimates, are known for comparison. Some applications of the program are then given for some non-trivial situations, such as the nanoparticle and polymer systems mentioned before. The path-integration method is evidently a powerful tool for computing basic electromagnetic and transport properties of complex-shaped polymers and should find wide application in polymer science, engineering, nanotechnological applications and medical and biological applications.

Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 1027 Unified Description of Chirped Gaussian Pulse Propagation of Arbitrary Initial Width in a Multiple Resonance Lorentz Medium Constantinos M. Balictsis Hellenic Telecommunications and Post Commission 60 Kifissias Avenue, Maroussi, Athens 15125, Greece Abstract Research interest regarding the reproducible generation, compression and characterization of ultrashort, pulse-modulated signals whose duration is comparable to the carrier oscillation cycle, is on the rise and spans various frequency domains [1 3]. Increased emphasis is placed on their dynamical evolution as they propagate through, and interact with, various material media due to the diverse and important applications, among others, in optical communications, radar systems and pulse compression. Pertinent theoretical efforts commonly invoke the slowly varying envelope approximation (SVEA) and are inapplicable in the sub-cycle pulse regime [1, 3]. A different stream of rigorous theoretical efforts to pulse propagation problems employs asymptotic techniques. These efforts have elucidated the dynamical evolution of the propagated field due to rapid rise and/or fall time or exponentially varying input pulses and their accuracy has been validated upon comparison with purely numerical results [1]. Recently, modern asymptotic techniques have been utilized in order to obtain an accurate uniformly valid description of Gaussian pulse propagation in a single-resonance causally dispersive, absorptive [4] or amplifying [5], Lorentz medium. Here, the unified asymptotic approach is applied to the important case of an input Gaussian pulse envelope modulated chirped harmonic wave whose envelope has a fixed but otherwise arbitrary initial full width 2T centered around t 0 > 0, and it modulates a harmonic wave of applied carrier frequency ω c that is linearly chirped with a constant chirp parameter C. This input chirped Gaussian wave propagates in the source-free half-space z 0 filled with a linear, homogeneous, isotropic temporally dispersive, non-hysteretic medium whose refractive index is described by the more realistic [1] multiple (m) resonance Lorentz model. The unified approach, which relies on an asymptotic analysis of the unified, exact integral representation of the propagated field, is shown to be valid from the SVEA to the theoretically and experimentally important sub-cycle pulse regimes, and its accuracy is confirmed upon comparison with the respective depicted results of an independent numerical experiment. Moreover, it generalizes previous findings on the appearance and dynamical evolution of the precursor fields associated with ultrashort and/or ultrawideband pulse propagation [1, 3 5]. According to the obtained unified asymptotic description, the propagated field A(z, t) is comprised of pulse components A Ul (z, t) each being due to the asymptotic contribution of a respective relevant saddle point ω SPUl (θ) of the unified phase function Φ U (ω, θ). This asymptotic description directly relates the propagation characteristics (including, the locus and propagation velocity of the stationary point(s) of the envelope, and the instantaneous angular oscillation frequency) of each A Ul (z, t) with the dynamics of the respective relevant saddle point ω SPUl (θ). Under certain conditions, such a stationary point of a pulse component s envelope occurs when the respective saddle point trajectory intersects the real frequency axis, and it travels with the group velocity at this frequency crossing value; superluminal velocity may then be observed. The accuracy and insight of the unified asymptotic description may prove useful in applications involving chirped pulses, overcoming the limitations of other theoretical approaches especially in the extremely ultrashort pulse regime. REFERENCES 1. Oughstun, K. E., Electromagnetic and Optical Pulse Propagation 2: Temporal Pulse Dynamics in Dispersive, Attenuative Media, Springer, New York, 2009. 2. Agrawal, G. P., Fiber Optic Communication Systems, Chapter 2, John Wiley & Sons Inc., New York, 1992. 3. Akhmanov, S. A., V. A. Vysloukh, and A. S. Chirkin, Optics of Femtosecond Laser Pulses, Chapter 1, American Institute of Physics, New York, 1992. 4. Balictsis, C. M. and K. E. Oughstun, Generalized asymptotic description of the propagated field dynamics in Gaussian pulse propagation in a linear, causally dispersive medium, Phys. Rev. E, Vol. 55, 1910 1921, 1997. 5. Balictsis, C. M., Unified asymptotic description of Gaussian pulse propagation of arbitrary initial pulse width in a Lorentz-type gain medium, Phys. Rev. E, Vol. 87, 013304, 2013.

1028 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 Block LU Preconditioner for the Electric Field Integral Equation S. L. Stavtsev INM RAS, Russian Federation Abstract Boundary element discretizations are applied in many scientific and engineering areas, for example, to solve the problem of electromagnetics scattering with electric field integral equation (EFIE). To solve EFIE on the surfaces of arbitrary shape, RWG functions are traditionally used. The matrices, arising from the discretization of integral equations can be approximated well with low-rank matrices using mosaic-skeleton method. But to solver scattered problem with large wave size of object we have to solve large system n 10 5 10 6. System of linear equation with matrixes of such order is solved by iterative method (GMRES). For large wave size matrix is ill-condition and we have to use preconditioner. In this paper to decrease a number iteration of GMRES method the block LU preconditioner is built. In the numerical experiments it is showed that the preconditioner permit to solve the problem of electromagnetic scattering on objects with lager wave size.

Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 1029 Permittivity Reconstruction of a Diaphragm in a Rectangular Waveguide: Unique Solvability of Benchmark Inverse Problems Y. Shestopalov 2, Y. Smirnov 1, and E. Derevyanchuk 1 1 Penza State University, Russia 2 University of Gävle, Sweden Abstract Determination of electromagnetic characteristics of dielectric bodies is an urgent problem for artificial materials: nanomaterials, metamaterials, and nanocomposite materials. As a rule, electromagnetic parameters of modern materials cannot be measured. Therefore for solving this problem, methods of mathematical modeling must be applied. In this work, we consider the inverse problem of permittivity reconstruction of diaphragms loaded in a rectangular waveguide and present theoretical and numerical results. This work is a continuation of the series of papers [1 3] devoted to the investigation of permittivity reconstruction of layered materials in the form of diaphragms (sections) in a single-mode waveguide of rectangular cross section from the transmission coefficient measured at different frequencies. The aim is the development of the mathematical technique for the analysis of the inverse problem for the case of a one- and multi-sectional diaphragms in a rectangular waveguide. We suppose that the diaphragm is made of material with real electromagnetic parameters. For this case, we obtain analytical solution of the inverse problem. Based on the analytical solution we study more complicated mathematical models, consider different cases of filling the diaphragm sections, and present results of numerical simulation. We perform comparison of experimental and numerical results that validate the efficiency of the proposed technique. The obtained solutions can be implemented in practical measurements for the investigation of new artificial materials and media and can be applied in optics, nanotechnology, and design of microwave devices. REFERENCES 1. Smirnov, Yu. G., Yu. V. Shestopalov, and E. D. Derevyanchuk, Permittivity reconstruction of layered dielectrics in a rectangular waveguide from the transmission coefficient at different frequencies, Inverse Problems and Large-Scale Computations, Series: Springer Proceedings in Mathematics and Statistics, Vol. 52, No. 12, 169 181, 2013. 2. Smirnov, Yu. G., Yu. V. Shestopalov, and E. D. Derevyanchuk, Solution to the inverse problem of reconstructing permittivity of an n-sectional diaphragm in a rectangular waveguide, Algebra, Geometry and Mathematical Physics, Springer Proceedings in Mathematics and Statistics, Vol. 85, Ser. 10533-2014, 555 567, 2014. 3. Smirnov, Yu. G., Yu. V. Shestopalov, and E. D. Derevyanchuk, Permittivity determination of multi-sectional diaphragm with metamaterial layers in rectangular waveguide, PIERS Proceedings, 135 139, Taipei, Mar. 25 28, 2013.

1030 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 The Application of Non-linear Dynamics Methods for Radar Target Identification F. J. Rachford and T. L. Carroll US Naval Research Laboratory, USA Abstract Currently radar target identification is effected by finding the downrange distribution of scatterers on a platform using high definition radar and referencing this distribution to a look-up table of measured radar returns. This method is difficult due to the rapid scintillation of the radar signal of a flying target at short wavelengths. We investigate a method of target identification in the low definition, relatively long wavelength, limit using techniques derived from the field of non-linear dynamics. In this limit the radar reflection is much less sensitive to the orientation of the target to the radar and scintillation is greatly reduced. Modern detection advances allows the digitization and processing of raw real time non-pulse compressed waveforms. We simulate the raw radar returns from several very similar small (4 to 5 wavelength) objects (i.e., cylinder, cone-cylinder, cone-ogive and double ogive) illuminated with chaotic or random modulated waveforms using a commercial finite difference time domain code. In this aggressive limit we embed the return in two dimensions using the method of delays to form an attractor. The geometric properties of the attractors are analyzed to distinguish between these similar target objects in the low definition limit. One method selects points on a reference attractor (or strands of points) with many Euclidean nearest neighbors and compares these with the nearest neighbor density of points (or strands) with the same time index on an attractor from an unknown target. Comparing the density of nearest neighbors at these points on two attractors allows us to calculate probabilities of correct identification. (Is the unknown signal from the reference target or from one of the other targets?) The robustness of our method is probed by the addition of white noise and/or simulated clutter to the signals.

Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 1031 Verification of Computational Model of Transmission Coefficients of Waveguide Filters P. Tomasek 1 and Y. V. Shestopalov 2 1 Tomas Bata University in Zlin, Czech Republic 2 University of Gävle, Gävle, Sweden Abstract Owing to the recent research [1 3] the way of estimating transmission coefficients for a waveguide of rectangular cross-section loaded with multi-layered parallel-plane dielectrics is found. Consequently, the analysis of the transmitted and reflected fields in terms of the scattering matrix formalism can be performed explicitly. These results can be efficiently applied to modeling of waveguide filters. This article is mainly based on the previous research presented in [1], it enhances the theory and contains comparisons between real measured and computed transmission coefficients of a waveguide filter using a technique based on the method set forth in [2, 3]. The computation employs analysis of closed-form solutions and numerical multi-parameter optimization [4, 5]. The presented waveguide filter is formed by multi-sectional diaphragms placed in a waveguide of rectangular cross-section. The filter consists of a specific combination of diaphragms of FR4, plexi and RO4003 with defined permittivities and thicknesses. The resulting permittivity profile that provides significant range of the parameter and output variations has a characteristic almost-periodic stepwise structure which can be improved using the closed-form solution and numerical optimization. Comparison of the computed and measured transmission coefficients demonstrates that the difference is very low, rather marginal and thus the output of the work is considerably promising. The results prove the ideas, approach and the final implementation of the mathematical background used for computation of the transmission coefficients of a waveguide filter. REFERENCES 1. Tomášek, P. and Y. Shestopalov, Parameter optimization of waveguide filters employing analysis of closed-form solution, PIERS Proceedings, 296 299, Stockholm, August 12 15, 2013. 2. Shestopalov, Y. and Y. Smirnov, Inverse scattering in guides, J. Phys.: Conf. Ser., Vol. 346, 012019, 2012. 3. Shestopalov, Y., Y. Smirnov, and E. Derevyanchuk, Permittivity determination of multisectional diaphragm with metamaterial layers in rectangular waveguide, PIERS Proceedings, 135 139, Taipei, March 25 28, 2013. 4. Chan, R., R. Mittra, and T. Cwik. Techniques for analyzing frequency selective surfaces A review, IEEE, Vol. 76/12, 1593 1615, 1988. 5. Antoniou, A. and W. S. Lu, Practical Optimization: Algorithms and Engineering Applications, Springer, Pvt. Limited, India, 2009.

1032 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 Computations Related to Nanoparticle Characterization and Nanocomposite Property Estimation Fernando Vargas-Lara and Jack F. Douglas Materials Science and Engineering Laboratory, NIST, Gaithersburg, MD 20879, USA Abstract Recently, there has been great interest in enhancing the electrical and thermal conductivity and mechanical properties of polymeric materials with carbon nanotube (CNTs) additives. Large changes in properties have been achieved with these additives and applications, especially in relation to enhanced electrical conductivity, have been realized. However, controlling and understanding these property changes has been a difficulty. It is well known that the resulting nanocomposite properties depend strongly on the geometrical properties of the CNTs such as length, diameter, and shape, as well as the dispersion of the CNT. Commercial forms of these fillers, as opposed to the rod-like structures that are the focus of many academic studies, are typically composed of roughly spherical multi-walled CNT domains having a highly ramified internal structure and a size on the order of a micron. Clearly, such structures, which we term tumbleweeds because their resemblance to these natural forms, cannot reasonably be modeled as rods, and we address the properties of these composite materials through a combination of molecular dynamics simulations and path-integral calculations. As a specific illustration of this computational path, we first calculate electromagnetic properties of the tumbleweeds, such as the self-capacitance, electric polarizabilty tensor, and the intrinsic conductivity. Knowing these basic particle properties, one then can estimate electromagnetic properties of nanocomposites made with these complex- shaped particles, i.e., conductivity, by incorporating this information in a generalized effective medium theory. Based on this model, we find that the conductivity percolation threshold of the tumbleweeds can be quite low, despite their quasi-spherical average shape.

Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 1033 Exponential Regularization of EM Dyadic Green s Functions via Green s Function-induced Dirac δ-functions A. R. Baghai-Wadji University of Cape Town, South Africa Abstract In a series of recently published contributions it was shown that dyadic Green s functions arising in computational electromagnetics can be utilized to construct problem-specific integral representations of the Dirac delta function. It was also shown that the constructed Dirac delta functions can be employed to regularize originating Green s functions associated with Poisson equation in isotropic and anisotropic dielectrics. This contribution extends previous efforts as follows: (i) The constructed Dirac delta functions are employed to regularize dyadic Green s functions associated with Maxwell s equations in isotropic media. Thereby, all formulae arising in the discussion are expressed in closed-form in spectral domain, a fact which allows intriguing insights into the dynamics of the proposed regularization method itself. (ii) Complex media do not allow the Green s functions to be constructed in closed form. Consequently, the integral representations for the Dirac delta functions cannot be expressed in closed-form either. An algorithm is presented for the numerical construction of Dirac delta functions. It is claimed that the latter result presents a genuine contribution to the computational physics. (iii) The soundness of the derivations are supported by several Lemmas. (iv) Applications in which near field phenomena play a decisive role, e.g., nanoscopic and plasmonic devices will benefit from the results. Regularization problems arising in theoretical and computational field theory are fascinating and challenging at the same time; numerically, however, they are most undesirable and may lead to catastrophically ill-conditioned results. Singular field problems, requiring regularization, have characteristic footprints in spectral domain. Singularities in static fields are defined by a 1/ k pole-like behavior in the infrared wavenumber region. The same 1/ k functional behavior in the ultraviolet region leads to slow convergent or divergent Fourier-type integrals. In real domain, the infrared 1/ k pole-like singularity is associated with the properties of the fields in the far-field, whereas, the ultraviolet slow-decay, divergent singularity is related to the near-field. Singularities in dynamic fields manifest themselves in poles and branch points in intermediate regions in spectral domain. It can shown that pole- and branch point singularities can be treated fairly conventionally, with one exception, which arises when constructing universal functions (addressed in an accompanying paper). Thus the prime focus becomes regularization of slow decay property of Green s functions in spectral domain (near-field region). To this end the present author has proposed algebraic as well exponential regularization techniques. This paper focuses on the exponential regularization which is facilitated by Dirac delta functions constructed from the Green s functions themselves. ACKNOWLEDGMENT This work is based on the research supported in part by the National Research Foundation (UID: 93114). REFERENCES 1. Baghai-Wadji, A. R., Self-consistent physics-based δ η -regularized Green s function for 2D Poissons equation in anisotropic dielectric media, Proceedings of the Applied Computational Electromagnetics Society, Jacksonville, Florida, USA, 2014. 2. Baghai-Wadji, A. R., Self-consistent physics-based δ η -regularized Green s function for 3D Poissons equation in anisotropic dielectric media, Proceedings of the Applied Computational Electromagnetics Society, Jacksonville, Florida, USA, 2014. 3. Baghai-Wadji, A. R., 3D electrostatic charge distribution on finitely-thick bus-bars in microacoustic devices: Combined regularization in the near-and far-field, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Special Issue, 2014 (Invited).

1034 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 Superresolution Based on the Methods of Extrapolation B. A. Lagovsky 1, A. B. Samokhin 1, and Y. V. Shestopalov 2 1 Department of Applied Mathematics Moscow State Technical University of Radio Engineering, Electronics and Automatics, Russia 2 University of Gävle, Sweden Abstract One of the most important ways to improve the radar systems based on smart antennas is to improve the accuracy of angle measurements and to increase the angular resolution. In this regard, the problem to be solved is restoring the image of the object with superresolution. This inverse problem is reduced to a Fredholm integral equation U(α) = F (α φ, ϕ)i(φ, ϕ)dφdϕ, (1) Ω where U(α) is the signal received by the scanning, Ω angular region of location of the signal source, I(α, ϕ) desired angular distribution of the reflected signal amplitude, and F (α, ϕ) radiation pattern. The central problem based on the intelligent analysis and digital signal U(α) is to restore the image of the source using superresolution. In contrast to conventional phased array, the signals received by each element of the smart antennas can be recorded digitally. The new signal processing method is based on the extrapolation of the signals received by each element of the smart antennas beyond the aperture and yields synthesized smart antennas with a greater number of emitters and an aperture increased by the same factor. As a result, the accuracy of angular measurements and angular resolution increases. The best results were obtained using the extrapolation with the Berg linear prediction method. The algorithm predicts the values of the signals for the aperture array ten times higher than the original one with a negligible error. Numerical studies have shown that the Rayleigh criterion in this problem is exceeded by 6 7 times. An important characteristic of solutions is a minimal signal/noise ratio (SNR) with which a super-resolution image reconstruction is still possible. Stability of solutions and quality of image reconstruction were examined using a mathematical model. The results of numerical studies show that the angular resolution is increased 4 10 times under SNR 12 13 db, which is much lower than that achieved by the known methods. The proposed new method of signal processing based on digital aperture synthesis significantly improves the accuracy of angle measurements and provides a stable restoration of detailed images of the objects with superresolution in the presence of small distortions. The corresponding algorithm can be implemented in the real-time mode.

Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 1035 Analysis of Quasi-circular Polarization in Near Field of Smart Shelf RFID Antenna Radiation A. S. Andrenko SYSU-CMU Shunde International Joint Research Institute No. 9 Eastern Nanguo Road, Shunde, Guangdong 528300, China Abstract This paper presents the EM simulation and accurate analysis of quasi-circular polarization (CP) of the so-called smart shelf antenna designed for the UHF RFID retail and item-tagging applications. The smart shelf antenna utilizes the near field communication in a range close to a wavelength between the planar reader/writer antenna and several tagged items being placed on the shelf. To provide reliable detection of the multiple tags which can generally be distributed within a wide interrogation volume over the shelf surface, uniform and strong near E-field radiated be the smart shelf antenna is required. The design of the proposed antenna is based on the EM coupling between the open-ended or shorted-to-the ground meander microstrip line utilizing the standing wave current-voltage distribution and periodic metal strips printed on the top surface of a dielectric substrate. The required uniform near E-field has been provided by optimizing the layout of the periodic strips forming the smart shelf antenna layout. Series of full-wave EM simulations have been carried out to analyze the E-field distribution calculated at the different distances from the antenna surface, in a range from 5 cm to 40 cm. It has been confirmed that the proposed antenna creates strong near field within the entire volume where multiple RFID tags are placed. Two types of the smart shelf antenna have been designed and optimized. The first is the antenna where the periodic EM coupled elements are straight strips of approximately one wavelength so that the smart shelf antenna radiates predominantly linearly polarized E-field. The second one has been designed for the apparel tagging applications where tagged items are arbitrary oriented in the plane parallel to the antenna surface. Therefore, EM near field of this antenna has to be quasi-cp with quasi here meaning that the E-field is also having z-component (normal to antenna surface). What is the most important in such an application is that the E-field has to have a well balanced x- and y-components at the different distances from antenna and within an entire interrogation volume. The required quasi-cp near field has been numerically optimized in the series of EM simulations by utilizing the three-section layout of the periodic metal strips and changing the angles of strip sections so that it results in both E x - and E y -components being produced. Time-domain calculation of 3D E-field vector distribution has also demonstrated how a simple change of the meander line layout produces both quasi-rhcp and LHCP radiation in the near field. The prototypes with different layouts of the proposed antenna have been produced and their performance in the UHF RFID system has been verified. 100% detection rate and measured read range for the large number of tagged items have confirmed the simulated near field distribution as well as an excellent performance of the proposed smart shelf antenna.

1036 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 CICT: A Novel Framework for Biomedical and Bioengineering Application R. A. Fiorini Department of Electronics, Information and Bioengineering (DEIB) Politecnico di Milano University, Italy Abstract In 2004, University of Michigan physicist Mark Newman, along with biologist Michael Lachmann and computer scientist Cristopher Moore, showed that if electromagnetic radiation is used as a transmission medium, the most information-efficient format for a given 1-D signal is indistinguishable from blackbody radiation. Since many natural and biological processes maximize the Gibbs-Boltzmann entropy, they should give rise to spectra indistinguishable from optimally efficient transmission. In 2013, Politecnico di Milano academic scientist R. A. Fiorini confirmed Newman, Lachmann and Moore s result, generating analogous example for 2-D signal (image), as an application of CICT (computational information conservation theory) to show that even the current, most sophisticated instrumentation system is completely unable to reliably discriminate so called random noise (RN) from any combinatorially optimized encoded message, which CICT called deterministic noise (DN). For observing and determining single molecule transport characteristics or for detecting a minute change in resistance or capacitance at biostrucuture nanoscale, we need stronger research and computational tools able to overcome the above operative limitation. To grasp a more reliable representation of experimental reality and to get stronger physical and biological system correlates, researchers and scientists need two intelligently articulated hands: both stochastic and combinatorial approaches synergically articulated by natural coupling. CICT approach brings classical and quantum information theory together in a single framework, by considering information not only on the statistical manifold of model states but also from empirical measures of low-level multiplicative noise source generators, related to experimental high-level overall perturbation. This approach is recommended to design reliable experiment and advanced instrumentation system. In various applications to physical problems, a function can be decomposed into physically meaningful eigenfunctions of a differential operator (typically the Laplace operator): this forms the foundation for the spectral study of functions, in reference to the spectrum of the differential operator. A concrete physical application involves the problem of hearing the shape of a drum: given the fundamental modes of vibration that a drumhead is capable of producing, can one infer the shape of the drum itself? The mathematical formulation of this question involves the Dirichlet eigenvalues of the Laplace equation in the plane, that represent the fundamental modes of vibration in direct analogy with the integers that represent the fundamental modes of vibration of the violin string. Spectral theory also underlies certain aspects of the Fourier transform of a function. Whereas Fourier analysis decomposes a function defined on a compact set into the discrete spectrum of the Laplacian (which corresponds to the vibrations of a violin string or drum), the Fourier transform of a function is the decomposition of a function defined on all of Euclidean space into its components in the continuous spectrum of the Laplacian. The Fourier transformation is also geometrical, in a sense made precise by the Plancherel theorem, that asserts that it is an isometry of one Hilbert space (the time domain) with another (the frequency domain). This isometry property of the Fourier transformation is a recurring theme in abstract harmonic analysis, as evidenced for instance by the Plancherel theorem for spherical functions occurring in noncommutative harmonic analysis. For discrete data, the Discrete Fourier Transform (DFT) is used. As an example, CICT number theoretic transform (NTT) is presented to envisage the development of competitive application devoted to automatic tailoring noise compensation countermeasure to real dynamic device characteristics and performance, even in real-time. That feature can get us closer to ideal self-registering and self-linearizing instrumentation able to generate virtually homogeneous and uniform device experimental probing domain, during its whole designed service life-cycle, offering superior reliable final result at least cost. Its adoption becomes a must either to real High Reliability Organization (HRO) or to mission critical project for low technological risk and crisis management system.

Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 1037 Multichannel Filter Banks and Their Implementation Using Computers with a Parallel Structure D. I. Kaplun, D. M. Klionskiy, A. S. Voznesenskiy, and V. V. Gulvanskiy Computer Science Department Saint Petersburg Electrotechnical University LETI, Saint Petersburg, Russian Federation Abstract The paper is devoted to the development and software-hardware implementation of the weighted overlap-add algorithm (WOLA-algorithm) for processing vector signals in wideband monitoring tasks. The algorithm is intended for functioning together with instruments that are responsible for airwave control in real time. We have performed the comparison of the suggested algorithm with the polyphase implementation of a multichannel digital filter bank. We have also considered the software-hardware implementation of multichannel processing and we have shown the advantages of applying the CUDA (Compute Unified Device Architecture) technology based on computations using graphical processors. The WOLA-algorithm for processing vector signals can be considered as a generalization of the corresponding algorithm for processing one-dimensional signals. The suggested modification will make it possible to process a vector signal and also to perform software-hardware implementation using high-performance software and hardware tools. When we have found signals in each channel it is necessary to perform their sub-band processing (each channel signal has its own frequency band) including spectral analysis, time-frequency analysis, statistical analysis in the time domain, demodulation, etc.. Digital filter banks perform parallel processing of an input signal and therefore to improve the hardware implementation efficiency it is most reasonable to employ computers with a parallel structure. Such computers include FPGA (field-programmable gate arrays) and processing devices with the use of CUDA. CUDA is based on using a set of parallel graphical processors (Graphics Processing Unit GPU) for handling non-graphical tasks. GPU is a specialized device, which is a co-processor to the Central Processing Unit (CPU), has its own memory and can execute a large number of separate data flows (data flows are parts of one program that run in a parallel way). The advantages of CUDA are cross-platform operation, the existence of complete libraries, use of the extended version of C with additional tools for parallel programming and development of multiflow applications. Furthermore, CUDA does not require application of a graphical interface (API), which has a number of restrictions on multiflow computation arrangements. Hardware resources for digital filter bank implementation are not boundless (the most critical aspect is the total number of multipliers for FPGA). For this reason we need to design computationally efficient FIR-filters (filters with finite impulse response) that will allow us to reduce hardware-software costs and accelerate signal analysis. Such an approach will make it possible to reduce the total number of devices (including the number of FPGA multipliers) and increase the number of processing devices on a chip. We suggest performing filter bank implementation using FPGA and the distributed arithmetic. The main difference between this approach and direct implementation with MAC-cores (multiply and accumulate cores) is the fact that the distributed arithmetic does not use any multipliers. Thus we can achieve a more efficient digital filter bank implementation.

1038 Progress In Electromagnetics Research Symposium Abstracts, Prague, Czech Republic, July 6 9, 2015 Regularization of Ill-conditioned Numerical Scheme of an Analytical Formulation: Scattering by Circularly Layered Cylinders Emrah Sever 1, Fatih Dikmen 1, Farhad Mazlumi 2, and Yury A. Tuchkin 1 1 Electronics Engineering Department, Gebze Technical University, Kocaeli, Turkey 2 Aviation Electronics Department, Civil Aviation Technology College, Tehran, Iran Abstract The new regularization of the well-known analytical formulation of the monochromatic electromagnetic wave scattering by a few eccentrically multilayered homogenous circular dielectric [1] and impedance [2] cylinders will be demonstrated. The polarization of the fields are parallel to the longitudinal axes of the cylinders, thus a two dimensional problem for each both polarizations are under consideration. The ways to simulate such a physical or an engineering process are quite various, owing to the present techniques of using the capabilities of modern hardware and software. Therefore nowadays, the numerical stability of an analytically rigorous formulation of an electromagnetic scattering problem may be taken for granted unintentionally by the user of a powerful computer with modern hardware and software. We can meet the concerns about the numerically stable simulation of an analytical model, starting at least five decades ago [3, 4]. The formulation and its regularization in [3] were suggested for two neighboring perfectly conducting circular cylinders. We present herein the novel extension of the approach in [3] to the considered scattering problem. The integral formulation defined in [4], also having met in [5] gives the strong mathematical background of the analysis here. The main theoretical result herein is the mathematically equivalent reducing of the diffraction problem for the eccentrically multilayered dielectric circular cylinders to a linear algebraic equation system of the second kind in the functional space l 2. The numerical results to be presented will forewarn those who trust in the various numerical methods (even the classical ones) without a careful mathematical and numerical investigation of the methods validity. REFERENCES 1. Dikmen, F., E. Sever, S. Vatansever, and Y. A. Tuchkin, Well-conditioned algorithm for scattering by a few eccentrically multilayered dielectric circular cylinders, Radio Science, accepted, DOI: 10.1002/2014RS005501, 2015. 2. Sever, E., F. Dikmen, O. A. Suvorova, and Y. A. Tuchkin, An analytical formulation with illconditioned numerical scheme and its remedy: Scattering by two circular impedance cylinders, Turk. J. Elec. Eng. & Comp. Sci., accepted, DOI:10.3906/elk-1312-262, 2014. 3. Ivanov, E. A., Diffraction of Waves from Two Bodies, Nauka i Tekhnika, Minsk, 1968 (in Russian and Translated to English as NASA TT F-597). 4. Bates, R. H. T., Analytic constraints on electromagnetic field computations, IEEE Trans. Microwave Theo. Tech., Vol. 23, 605 623, 1975. 5. Ioannidou, M. P., K. D. Kapsalas, and D. P. Chrissouludis, Electromagnetic-wave scattering by an eccentrically stratified, dielectric cylinder with multiple, eccentrically stratified, cylindrical, dielectric inclusions, Journal of Electromagnetic Waves and Applications, Vol. 18, No. 4, 495 516, 2004.