Dragan Poljak

Assistant Professor, Ph.D.

Address:

Department of Electronics

FESB

University of Split

R. Boskovica bb

HR-21000 Split

Croatia

Tel. +385 21 305 660, Fax. +385 21 563 877, E-mail: dragan.poljak@fesb.hr


Personal:

If I go insane, please don't put your wires in my brain

Roger Waters, 1970.


Professional experience:

DRAGAN POLJAK was born in Split, Croatia, on October 10, 1965. He received the B.S. degree in 1990, the M.S. degree in 1994 and the Ph.D. degree in 1996 from the University of Split, Croatia, respectively. Currently he is an assistant professor at the Department of Electronics, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, teaching subjects: Basic course of electrical engineering, Fields and waves in electronics, Numerical methods in electromagnetic field calculation, Medical electronic equipment, and Antennas.

His research interest is originated from the continuing work in computational methods in electromagnetics, particularly numerical modelling of wire antennas in the presence of inhomogeneous media and interaction of electromagnetic waves with human body.

In his master thesis he investigated the finite element solution of integral equations in wire antenna problems. One of the most important contributions is developing a certain variant of integral finite element technique for wire antennas and scatterers of arbitrary shape in the presence of a inhomogeneous medium. In addition, the so-called exponential approximation technique is successfully applied to the Sommerfeld integrals evaluation. This finite element/exponential approximation procedure provides accurate and efficient calculation of equivalent current distribution along wire, near and far field evaluation and very simple technique for input impedance evaluation.

Very similar approach has been used for calculating the transient impedance of the grounding systems for lightning protection applications. Time-domain response is obtained from frequency domain results by using the inverse fast Fourier transform algorithm.

Numerous advantages of proposed method over the commonly used point-matching technique are fully documented in his master thesis and several published papers in journals and conference proceedings.

He has also applied the finite element techniques for solving the problems of power cables heat transfer and semiconductor devices modeling, and boundary element solution of electromagnetic scattering from arbitrarily shaped 2D conducting bodies.

In his doctoral thesis he has developed a new time-domain formulation for the analysis of horizontal wire antenna radiating over a lossy half-space. The effect of a lossy medium is taken into account via space-time dependent reflection coefficient appearing inside the time-domain Hallen integral equation. An efficient and stable direct time-domain finite-element/marching-on-in-time procedure has also been developed for treating the corresponding integral -equation. Recently, the proposed formulation is extended to practically more interesting case of two coupled wires over a lossy interface. The similar approach is also successfully applied to the analysis of transmission lines of a finite length. Finally, this time-domain formulation is also used for the calculation of the foot current induced in human body exposed to electromagnetic pulse. Currently, he has a collaboration with the Department of Electrical and Electronic Engineering (electromagnetics research group) at the University of Wales, Swansea, sponsored by British Council.

Since October 1990, he has published many papers (see References) as a result of his continuous work in the area of computational electromagnetics.


References:

1) M.Smajo, D.Poljak, M. Popovic, T.Pokrajac: Measurements of Induction Motor Performances Supplied from PWM Commutator Based on Microcomputer, scientific report for Ministry of Science and Technology, University of Split, Dec. 1990. (in Croatian)

2) V. Roje, D.Poljak, I.Zanchi: Current Distribution for Cylindrical Dipole and its Influence on Mutual Impedance, Proc. ELMAR 34th International Symposium, pp 158-160, Zadar, Sept. 1992. (In Croatian)

3) V. Roje, D.Poljak, I.Zanchi: Current Distribution on an Arbitrarily Dimensioned Dipole, Elektrotehnika ELTHB2, 36, 1-2, pp 37-42, 1993. (In Croatian)

4) V. Roje, D. Poljak: Convergence of Numerical Solutions of Coupled Integral Equations - Cylindrical Antenna Application, 38th International Annual Conference KoREMA, Zagreb, April 1993. (In Croatian)

5) V. Roje, D. Poljak: A New Approach for Solving Integral Equations, Proc. 35th ELMAR International Symposium, pp 193-196, Zadar, Sept. 1993. (In Croatian)

6) D. Poljak, V. Roje: The Weak Finite Element Formulation for Pocklington's Integro-Differential Equation, Int. Journ. Engineering Modelling, 6 (1-4), pp 21-25, 1993.

7) B.Jajac, D.Poljak: Calculation of heat transfer from hot gas pipeline and power cables in inhomogeneous ground, report for "Elektroprojekt - Zagreb", University of Split, April 1994. (In Croatian)

8) V. Roje, D. Poljak: The Finite Element Near Field Calculation, 39th International Annual Gathering KoREMA, pp 47-50, Zagreb, 1994. (in Croatian)

9) V. Roje, D.Poljak: Electromagnetic Waves Analysis Software, Proc. Conference of software in telecommunications and computer netwoks, SoftCOM'94, pp 137-144, Split, June 1994. (In Croatian)

10) D. Poljak, V. Roje: Analysis of Wire Antennas Radiating Over Lossy Half-Space, Proc. 36th ELMAR International Symposium, pp 196-199, Bozava, Sept. 1994.

11) B.Jajac, D.Poljak, V.Srzentic: The Synchronous Machine Parameters Calculation by means of Schwartz-Christoffel transformation, Elektrotehnika ELTHB2, 37, 5-6, pp 227-233, 1994. (In Croatian)

12) D.Poljak, V.Roje: Calculation of the Wire Antenna Parameters by Finite Element Method, Elektrotehnika ELTHB2, 38, 1-2, pp 21-30, 1995. (In Croatian)

13) D.Poljak, V.Roje: Input Impedance of Dipole Antenna over Dissipative Medium, 40th Int. Ann. Gath. KoREMA, pp 23-26, Zagreb, April 1995.

14) B.Jajac, D.Poljak: The Effect of Thermal Backfill on Power Cables Heat Transfer, Part I: Mathematical Model, Elektrotehnika ELBTH2, 38, 3, pp 95-99, 1995. (In Croatian)

15) B.Jajac, D.Poljak: The Effect of Thermal Backfill on Power Cables Heat Transfer, Part II: Boundary Conditions and Numerical Results, Elektrotehnika ELBTH2, 4-5, 38, pp 173-180, 1995. (In Croatian)

16) V.Roje, D.Poljak: Modelling of Semiconductor devices by finite elements, Proc. of MEET '95, 2/50 - 2/55, ÁIPRO, Opatija, May 1995. (In Croatian)

17) D.Poljak, V.Roje: Application of Boundary Element Method to Scattering from Conducting Cylinder of Arbitrarily Cross-Section, Proc. Conference of software in telecommunications and computer netwoks, SoftCOM'95., pp 301-310, Split, June 1995. (In Croatian)

18) B.Jajac, D.Poljak: Numerical Calculation of the Heat Transfer of Power Cable Placed in Thermal Backfill, report for "HEP-Elektrodalmacija", University of Split, June 1995. (In Croatian)

19) V.Roje, D.Poljak: Various Approaches for Solving Integral Equations in Electromagnetics, Proc. of the International Conference on Electromagnetics in Advanced Applications, ICEAA 95, pp 329-332, Turin, Sept. 1995.

20) D.Poljak, V.Roje: Methods for Sommerfeld Integrals Evaluation, Proc. 37th ELMAR International Symposium, pp 145-148, Pula, Sept. 1995.

21) D.Poljak: New Numerical Approach in Analysis of Thin Wire Radiating over Lossy Half-Space, Int. J. Num. Meth. Eng., Vol. 38, No. 22, pp 3803-3816, Nov. 1995.

22) D.Poljak, V.Roje: Boundary Element Approach to Calculation of Wire Antenna Parameters in the Presence of Dissipative Half-Space, IEE Proc. Microw. Antennas Propag. , Vol. 142, No. 6, pp 435-440, Dec. 1995.

23) D. Poljak: Finite Element Solution of Transient Radiation from Thin Wires, Int. Journ. Engineering Modelling, 8 (1-2), pp 31-35, 1995.

24) D.Poljak, V.Roje: Input Impedance of End-Driven Wire Antenna in Lossy Medium, Proc. 38th ELMAR International Symposium, pp 102-105, Zadar, June 1996.

25. B.Jajac, D.Poljak: Calculation of Steady State Temperature Distribution Around Power Cable Placed in the Trench Backfill, Proc. 41st Int. Ann. Conference KoREMA, Vol. 1, pp 77-80, Opatija, Sept. 1996.

26. V.Roje, D.Poljak, M.Vojnovic: Finite Element Solution of Coupled Semiconductor Equations, Proc 41st Int. Ann. Conference KoREMA, Vol. 3, pp 31-34, Opatija, Sept. 1996.

27. B.Jajac, D.Poljak: Proracun temperaturnog polja na krizanju toplovoda i kabela - lokacija hotel Intercontinental-Zagreb, elaborat za "Elektroprojekt - Zagreb" , Split, listopad, 1996.

28) D.Poljak, V.Roje: Transient Response of a Thin Wire in a Two Media Configuration, Proc. of EMC'97 Symposium, Zurich, 293-296, Feb. 1997.

29) D.Poljak, V.Roje: Finite Element Technique for Solving Time-Domain Hallen Integral Equation, Proc. of ICAP'97, 1.225-1.228, Edinburgh, April 1997.

30) D.Poljak, V.Roje: Hundred Years of Thin Wire Integral Equations, Proc. 39th ELMAR International Symposium, pp 119-123, Zadar, June 1997.

31) B.Jajac, D.Poljak: Calculation of Nominal Current for 110kV Power Cable for TS (110/10(20)) kV Susak, report for "HEP" - Rijeka, Split, July, 1997.

32) D.Poljak, V.Roje: Boundary Element Analysis of Resistively Loaded Wire Antenna Immersed in a Lossy Medium, 19th International Conf. on Boundary Elements, BEM 19, pp 485-493, Rome, Sept. 1997.

33) D.Poljak, V.Roje: The Integral Equation Method for Ground Wire Input Impedance, in C. Constanda, J.Saranen, S.Seikkala (ed): Integral methods in science and Engineering, Vol. I, Longman, U.K., pp 139-143, 1997.

34) D.Poljak, V.Roje: Time-Domain Analysis of a Thin Wire Parallel to a Perfectly Conducting Ground Plane, 14th International Conf. on Applied Electromagnetics and Communications, ICECOM'97, pp 30-33, Dubrovnik, Oct. 1997.

35) D.Poljak, B.Jajac: Lightning Induced Current on a Metallic Post - Frequency Domain Analysis, 14th International Conf. on Applied Electromagnetics and Communications, ICECOM'97, pp 87-90, Dubrovnik, Oct. 1997.

36) D.Poljak, V.Roje: Time Domain Calculation of the Parameters of Thin Wire Antennas and Scatterers in a Half-Space Configuration, IEE Proc. Microw. Antennas Propag. , Vol. 145, No. 1, pp 57-63, Feb. 1998.

37) D.Poljak: Finite Element Integral Equation Modelling of a Thin Wire Loop Antenna, Communications in Numerical Methods in Engineering, 14, pp 347-354, 1998.

38) V. Roje, D.Poljak: Linear Antenna Model Applied to the Penetration of Electromagnetic Waves, Proc. 49th ELMAR International Symposium, pp 154-158, Zadar, June 1998.

39) D.Poljak: Transient Response of Resistively Loaded Straight Thin Wire in Half-Space Configuration, Journ. Electromagnetic Waves and Applications, Vol. 12, Vol. 12, 775-787, 1998.

40) D.Poljak, V.Roje: Input Impedance of Loaded Wire Antenna in the Presence of a Lossy Half-Space, Progress in Electromagnetics Research Symposium, PIERS'98, pp 1086, Nantes, France, July 1998.

41) D.Poljak, V.Roje: Time-Domain Boundary Element Analysis of Resistively Loaded Wire, Proc. 20th International Conf. on Boundary Elements, BEM 20, pp 157-166, Orlando, USA, Aug. 1998.

42) D.Poljak, V.Roje: Time Domain Modeling of Electromagnetic Field Coupling to Transmission Lines, Proc. 1988 IEEE EMC Symposium, pp 1010-1013, Denver, USA, Aug. 1998.

43) D.Poljak, B.Jajac: On the Use of Monopole Antenna Model in Lightning Protection System Analysis, Int. Symposium on Electromagnetic Compatibility, EMC Roma'98, pp 370-374, Roma, Sept. 1998.

44) V.Roje, D.Poljak: Wire antenna Theory Applied to teh Electromagnetic Interaction Problems with Loss Included, Proc. Conference of software in telecommunications and computer netwoks SoftCOM'98, Split, Dubrovnik, Bari, pp 627-636, Oct. 1998.

45) D.Poljak, V.Roje: Currents and Fields Induced in Human Being Exposed to the Electromagnetic Radiation, Proc. Conference of software in telecommunications and computer netwoks SoftCOM'98, Split, Dubrovnik, Bari, pp 637-646, Oct. 1998.

46) B.Jajac, D.Poljak: The Finite Element Analysis of Horizontal Wire Buried in a Lossy Ground, Int. Journ. Engineering Modelling, 11 (1-2), pp 7-14, 1998.

47) D.Poljak, B.Jajac: Finite Element Input Impedance Calculation of the Loaded Wire Above Perfect Ground, Int. Journ. Engineering Modelling, 11 (1-2), pp 15-20, 1998.

48) Poljak D., Roje V.: Currents Induced in Human Body Exposed to the Power Electromagnetic Field, Proc. 20th Annual Int. Conference of the IEEE Engineering in Medicine and Biology Society, pp 375-378, Hong Kong, 29.Oct.-1.11.1998.

49) D. Poljak: Penetration of a Electromagnetic Wave into a Human Body, Proc. of 2nd Seminar on EMC and Telecommunications (in Croatian), Split, Croatia, pp 45-78, Nov. 4-5, 1998.

50) D. Poljak, R. Simundic, S. Babic: Various techniques for the calculation of the foot current, Proc. of the 4th EBEA Congress, Zagreb, Croatia, pp 92-94, Nov. 19-21, 1998.

51) D. Poljak, A. Sarolic, V. Roje: Calculation of the foot current induced in human body exposed to electromagnetic pulse, Proc. of the 4th EBEA Congress, Zagreb, Croatia, pp 96-98, Nov. 19-21, 1998.


Software:

TDIES- Time-Domain Integral Equation Solver - source code for calculation of straight thin-wire response in the presence of a half-space.


Last update: January 26, 1999


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