Dragan Poljak - Academia.edu (original) (raw)
Papers by Dragan Poljak
2023 XXXVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)
Properties and Characterization of Modern Materials, 2016
The paper reviews numerical modeling of arbitrarily shaped wire antennas pertaining to some Elect... more The paper reviews numerical modeling of arbitrarily shaped wire antennas pertaining to some Electromagnetic Compatibility (EMC) issues in wind turbine (WT) analysis and design. The formulation is undertaken in the frequency domain and based on the related Electric Field Integral Equations—EFIE (Pocklington integro-differential equations for arbitrary wire structures in the presence of a lossy half-space). The influence of a dissipative half-space is taken into account via the rigorous Sommerfeld integral approach. The numerical solution of corresponding EFIE is carried out by means of the Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM) featuring the use of isoparametric elements while the Sommerfeld integrals are evaluated numerically. The corresponding transient response is obtained via the Inverse Fourier Transform (IFT). The computational examples are related to the transient response of WTs struck by lightning and the transient behaviour of the realistic grounding systems for WTs. The WTs are energized by either an ideal voltage or a current source, respectively. WT is represented by a corresponding multiple wire configuration, while the lightning channel is modelled as an equivalent lossy vertical wire attached to the wind turbine. Furthermore, the grounding system is composed from rings, horizontal and vertical electrodes, respectively.
2018 17th International Conference on Ground Penetrating Radar (GPR), 2018
The paper deals with the characterization of electric field radiated by a GPR antenna and transmi... more The paper deals with the characterization of electric field radiated by a GPR antenna and transmitted into a lossy medium. Realistic bow-tie GPR antenna is modeled as an equivalent dipole antenna with current distribution governed by Hallen integral equation. Electric field transmitted into a lossy medium is determined using Boundary Element formalism for the solution of field integral formulas. Electric field distribution at a certain depth is calculated using this procedure.
17th International Conference on Applied Electromagnetics and Communications, 2003. ICECom 2003.
Electromagnetic-thermal analysis of the human body exposed to base station antenna radiation is p... more Electromagnetic-thermal analysis of the human body exposed to base station antenna radiation is presented in this work. The formulation of the problem is based on a simplified cylindrical representation of the human body. Electromagnetic part of the analysis involves incident and internal field dosimetry, while the thermal model deals with the bio-heat transfer processes in the body. The electric field
2007 International Conference on Electromagnetics in Advanced Applications, 2007
... EMC vol. 46, 1, pp. 2004. [13]D. Poljak, S. Kresic, A Simplified Calculation of Transient Pl... more ... EMC vol. 46, 1, pp. 2004. [13]D. Poljak, S. Kresic, A Simplified Calculation of Transient Plane Waves in a Presence of an Imperfectly conducting Half-Space, Boundary Elements XXVII, pp 541-549, Orlando, 2005. [14] D.Poljak ...
The paper deals with the modeling of Tesla's transmitter by using the wire antenna theory app... more The paper deals with the modeling of Tesla's transmitter by using the wire antenna theory approach. The radiating part of the Tesla's transmitter is represented by an equivalent monopole antenna excited by an ideal current source replacing the Tesla's transformer. The formulation is based on the frequency domain homogeneous Pocklington integrodifferential equation. Solving the Pocklington equation numerically via the Galerkin Bubnov variant of the Indirect Boundary Element Method (GB-IBEM) [4] current distribution along the equivalent monopole antenna is obtained. Knowing the current distribution along the monopole antenna the radiated electric field is readily obained integrating the induced current along the wire. Some illustrative numerical results for the antenna current and related field is presented in the paper. This work should be regarded as an opener to this subject, i.e. the first step in the full wave model of the Tesla's transmitter.
Acta Iadertina, 2017
U radu se razmatra pitanje egzistencije vremena sa stanovišta filozofije i fizike. Naglašava sepo... more U radu se razmatra pitanje egzistencije vremena sa stanovišta filozofije i fizike. Naglašava sepovezanost entropije i smjera vremena od prošlosti prema budućnosti. Posebno se raspravljao poveznici McTaggartovih vremenskih nizova s nekim fizikalnim aspektima vremena kaošto je primjerice poveznica s Einsteinovom teorijom relativnosti. U radu se detaljno propitujeMcTaggartova konkluzija o nepostojanju vremena te se pruža dokaz da je ovaj filozofskidomišljen rezultat slučaj primjene onto-logičkoga contradictio in adjecto pravila racionalnosti.Konačno, u radu se navode neke novije filozofske i fizikalne hipoteze o prirodi vremena.
2021 International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2021
The paper deals with the calculation of active, reactive and apparent power along a horizontal st... more The paper deals with the calculation of active, reactive and apparent power along a horizontal straight thin wire scatterer of finite length. Once the current distribution and voltage distribution along the straight scatterer are determined by solving the Pocklington integro-differential equation and generalized telegrapher’s equation respectively, the active power, reactive power and apparent power are calculated from the well-known formulas arising from the circuit theory. Some illustrative computational examples are presented in the paper.
Journal of Electromagnetic Waves and Applications, 2020
IEEE Transactions on Plasma Science, 2018
Engineering Analysis with Boundary Elements, 2017
2016 24th International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2016
The paper deals with the comparison between the frequency domain and time domain analysis of tran... more The paper deals with the comparison between the frequency domain and time domain analysis of transient electric field generated by the ground penetrating radar (GPR) dipole antenna and transmitted into the dielectric half-space for GPR antenna. The time domain integral equation (TDIE) approach is based on the Hallen integral equation for half-space problems. The numerical solution is carried out via the space-time scheme of the Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM). The frequency domain formulation is based on the Pocklington's integro-differential equation which is solved by using the frequency domain scheme of the Galerkin Bubnov Indirect Boundary Element Method. The related transient response is obtained by means of the Inverse Fast Fourier Transform (IFFT). The Integral Equation combined with the transmission coefficient arising from modified image theory (MIT) represents the novel method for obtaining the transmitted electric field of a GPR antenna. This paper brings the comparison of the results obtained by different approaches in solving the Integral Equation. The calculated results agree satisfactorily.
ABSTRACT The paper deals with two models of Tesla's propagation concept of wireless trans... more ABSTRACT The paper deals with two models of Tesla's propagation concept of wireless transmission of energy. A transmission line (TL) approximation and antenna model approaches are both implemented to analyze the Tesla's propagation concept. The Tesla's propagation path through the ground has been represented by an equivalent conductor excited at one end by the current source. The current distribution and the voltage have been calculated analytically. In particular, the voltage is calculated from standard TL equation and Generalized Telegrapher's equation formulation. Results for the voltage and generated power are presented in the paper.
2006 International Conference on Software in Telecommunications and Computer Networks, 2006
The paper deals with human exposure to extremely low frequency (ELF) electric fields generated by... more The paper deals with human exposure to extremely low frequency (ELF) electric fields generated by transformer substation. The problem is twofold, i.e. it requires the calculation of power substation electric field and current density induced inside the human body. ELF electric field generated from a power substation is assessed by solving the Scalar Potential Integral Equation (SPIE) using the Source Element Method (SEM), a variant of the Indirect Boundary Element Method (IBEM). Knowing the electric field due to the substation the current density induced within the human being exposed to such field is obtained by solving the Laplace equation variant of the continuity equation using the direct Boundary Element Method with domain decomposition (BEM-DM). Some illustrative computational results for external electric field and internal current density are presented.
2007 19th International Conference on Applied Electromagnetics and Communications, 2007
Abstract The paper deals with different approaches for the analysis of electromagnetic field coup... more Abstract The paper deals with different approaches for the analysis of electromagnetic field coupling to overhead wires of finite length based on the wire antenna theory, and transmission line method (TLM). The formulation based on the wire antenna theory in the frequency domain is based on the corresponding Pocklington equation, while the time domain formulation is based on the space-time Hallen integral equation. Transmission line model is based on the frequency and time domain Telegrapher's equations.. The integro- ...
IEE Proceedings - Microwaves, Antennas and Propagation, 2000
... lnvcstigahig the wcciiracy ancl the coiivcigcncc ratc, tlic PLIISC, linear and parabolic shap... more ... lnvcstigahig the wcciiracy ancl the coiivcigcncc ratc, tlic PLIISC, linear and parabolic shapc rirnctions a1.c lcsktl for tlic siiiglwvirc nncl coupled-wire gcomdries, and tlic linear shapc fuiictioiis itrc found to bc the optiniiim choice rqyrdiiig accu~icy wiid coiivcrgcncc against ...
IEEE Transactions on Electromagnetic Compatibility, 2002
2023 XXXVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)
Properties and Characterization of Modern Materials, 2016
The paper reviews numerical modeling of arbitrarily shaped wire antennas pertaining to some Elect... more The paper reviews numerical modeling of arbitrarily shaped wire antennas pertaining to some Electromagnetic Compatibility (EMC) issues in wind turbine (WT) analysis and design. The formulation is undertaken in the frequency domain and based on the related Electric Field Integral Equations—EFIE (Pocklington integro-differential equations for arbitrary wire structures in the presence of a lossy half-space). The influence of a dissipative half-space is taken into account via the rigorous Sommerfeld integral approach. The numerical solution of corresponding EFIE is carried out by means of the Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM) featuring the use of isoparametric elements while the Sommerfeld integrals are evaluated numerically. The corresponding transient response is obtained via the Inverse Fourier Transform (IFT). The computational examples are related to the transient response of WTs struck by lightning and the transient behaviour of the realistic grounding systems for WTs. The WTs are energized by either an ideal voltage or a current source, respectively. WT is represented by a corresponding multiple wire configuration, while the lightning channel is modelled as an equivalent lossy vertical wire attached to the wind turbine. Furthermore, the grounding system is composed from rings, horizontal and vertical electrodes, respectively.
2018 17th International Conference on Ground Penetrating Radar (GPR), 2018
The paper deals with the characterization of electric field radiated by a GPR antenna and transmi... more The paper deals with the characterization of electric field radiated by a GPR antenna and transmitted into a lossy medium. Realistic bow-tie GPR antenna is modeled as an equivalent dipole antenna with current distribution governed by Hallen integral equation. Electric field transmitted into a lossy medium is determined using Boundary Element formalism for the solution of field integral formulas. Electric field distribution at a certain depth is calculated using this procedure.
17th International Conference on Applied Electromagnetics and Communications, 2003. ICECom 2003.
Electromagnetic-thermal analysis of the human body exposed to base station antenna radiation is p... more Electromagnetic-thermal analysis of the human body exposed to base station antenna radiation is presented in this work. The formulation of the problem is based on a simplified cylindrical representation of the human body. Electromagnetic part of the analysis involves incident and internal field dosimetry, while the thermal model deals with the bio-heat transfer processes in the body. The electric field
2007 International Conference on Electromagnetics in Advanced Applications, 2007
... EMC vol. 46, 1, pp. 2004. [13]D. Poljak, S. Kresic, A Simplified Calculation of Transient Pl... more ... EMC vol. 46, 1, pp. 2004. [13]D. Poljak, S. Kresic, A Simplified Calculation of Transient Plane Waves in a Presence of an Imperfectly conducting Half-Space, Boundary Elements XXVII, pp 541-549, Orlando, 2005. [14] D.Poljak ...
The paper deals with the modeling of Tesla's transmitter by using the wire antenna theory app... more The paper deals with the modeling of Tesla's transmitter by using the wire antenna theory approach. The radiating part of the Tesla's transmitter is represented by an equivalent monopole antenna excited by an ideal current source replacing the Tesla's transformer. The formulation is based on the frequency domain homogeneous Pocklington integrodifferential equation. Solving the Pocklington equation numerically via the Galerkin Bubnov variant of the Indirect Boundary Element Method (GB-IBEM) [4] current distribution along the equivalent monopole antenna is obtained. Knowing the current distribution along the monopole antenna the radiated electric field is readily obained integrating the induced current along the wire. Some illustrative numerical results for the antenna current and related field is presented in the paper. This work should be regarded as an opener to this subject, i.e. the first step in the full wave model of the Tesla's transmitter.
Acta Iadertina, 2017
U radu se razmatra pitanje egzistencije vremena sa stanovišta filozofije i fizike. Naglašava sepo... more U radu se razmatra pitanje egzistencije vremena sa stanovišta filozofije i fizike. Naglašava sepovezanost entropije i smjera vremena od prošlosti prema budućnosti. Posebno se raspravljao poveznici McTaggartovih vremenskih nizova s nekim fizikalnim aspektima vremena kaošto je primjerice poveznica s Einsteinovom teorijom relativnosti. U radu se detaljno propitujeMcTaggartova konkluzija o nepostojanju vremena te se pruža dokaz da je ovaj filozofskidomišljen rezultat slučaj primjene onto-logičkoga contradictio in adjecto pravila racionalnosti.Konačno, u radu se navode neke novije filozofske i fizikalne hipoteze o prirodi vremena.
2021 International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2021
The paper deals with the calculation of active, reactive and apparent power along a horizontal st... more The paper deals with the calculation of active, reactive and apparent power along a horizontal straight thin wire scatterer of finite length. Once the current distribution and voltage distribution along the straight scatterer are determined by solving the Pocklington integro-differential equation and generalized telegrapher’s equation respectively, the active power, reactive power and apparent power are calculated from the well-known formulas arising from the circuit theory. Some illustrative computational examples are presented in the paper.
Journal of Electromagnetic Waves and Applications, 2020
IEEE Transactions on Plasma Science, 2018
Engineering Analysis with Boundary Elements, 2017
2016 24th International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2016
The paper deals with the comparison between the frequency domain and time domain analysis of tran... more The paper deals with the comparison between the frequency domain and time domain analysis of transient electric field generated by the ground penetrating radar (GPR) dipole antenna and transmitted into the dielectric half-space for GPR antenna. The time domain integral equation (TDIE) approach is based on the Hallen integral equation for half-space problems. The numerical solution is carried out via the space-time scheme of the Galerkin-Bubnov Indirect Boundary Element Method (GB-IBEM). The frequency domain formulation is based on the Pocklington's integro-differential equation which is solved by using the frequency domain scheme of the Galerkin Bubnov Indirect Boundary Element Method. The related transient response is obtained by means of the Inverse Fast Fourier Transform (IFFT). The Integral Equation combined with the transmission coefficient arising from modified image theory (MIT) represents the novel method for obtaining the transmitted electric field of a GPR antenna. This paper brings the comparison of the results obtained by different approaches in solving the Integral Equation. The calculated results agree satisfactorily.
ABSTRACT The paper deals with two models of Tesla's propagation concept of wireless trans... more ABSTRACT The paper deals with two models of Tesla's propagation concept of wireless transmission of energy. A transmission line (TL) approximation and antenna model approaches are both implemented to analyze the Tesla's propagation concept. The Tesla's propagation path through the ground has been represented by an equivalent conductor excited at one end by the current source. The current distribution and the voltage have been calculated analytically. In particular, the voltage is calculated from standard TL equation and Generalized Telegrapher's equation formulation. Results for the voltage and generated power are presented in the paper.
2006 International Conference on Software in Telecommunications and Computer Networks, 2006
The paper deals with human exposure to extremely low frequency (ELF) electric fields generated by... more The paper deals with human exposure to extremely low frequency (ELF) electric fields generated by transformer substation. The problem is twofold, i.e. it requires the calculation of power substation electric field and current density induced inside the human body. ELF electric field generated from a power substation is assessed by solving the Scalar Potential Integral Equation (SPIE) using the Source Element Method (SEM), a variant of the Indirect Boundary Element Method (IBEM). Knowing the electric field due to the substation the current density induced within the human being exposed to such field is obtained by solving the Laplace equation variant of the continuity equation using the direct Boundary Element Method with domain decomposition (BEM-DM). Some illustrative computational results for external electric field and internal current density are presented.
2007 19th International Conference on Applied Electromagnetics and Communications, 2007
Abstract The paper deals with different approaches for the analysis of electromagnetic field coup... more Abstract The paper deals with different approaches for the analysis of electromagnetic field coupling to overhead wires of finite length based on the wire antenna theory, and transmission line method (TLM). The formulation based on the wire antenna theory in the frequency domain is based on the corresponding Pocklington equation, while the time domain formulation is based on the space-time Hallen integral equation. Transmission line model is based on the frequency and time domain Telegrapher's equations.. The integro- ...
IEE Proceedings - Microwaves, Antennas and Propagation, 2000
... lnvcstigahig the wcciiracy ancl the coiivcigcncc ratc, tlic PLIISC, linear and parabolic shap... more ... lnvcstigahig the wcciiracy ancl the coiivcigcncc ratc, tlic PLIISC, linear and parabolic shapc rirnctions a1.c lcsktl for tlic siiiglwvirc nncl coupled-wire gcomdries, and tlic linear shapc fuiictioiis itrc found to bc the optiniiim choice rqyrdiiig accu~icy wiid coiivcrgcncc against ...
IEEE Transactions on Electromagnetic Compatibility, 2002