COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 EMC IN DIFFUSED COMMUNICATION SYSTEMS: CURRENT CAPABILITIES AND FUTURE NEEDS Vesna Roje University of Split, FESB R. Boškovića bb, Split, Croatia

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003  What has been done  On going work Electromagnetic field coupling to wire structure – antenna and scatterer mode. Modeling in frequency and time domain Safety aspects of the GSM base station radiation  Future work  Conclusion  List of some relevant references

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 What has been done wire antenna and scatter in free space wire over dielectric and conductive half space buried wire Modeling the wire structure for the simple structure: The formulation has been done in the frequency and then in time domain.

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 What has been done Electromagnetic field coupling to transmission lines Plain wave coupling to finite length cables (buried in lossy ground) Human body exposed to the electromagnetic fields (from ELF up to 1 GHz) Lightning return stroke current, near field, induced voltage and protection system Developed codes, even for such simple geometries were useful in EMC applications, such as in modeling:

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Ongoing work 1.The developed codes are expanded so to be useful for more complex geometry and could be applied to: Modeling of arbitrary wire configuration; Resolving the electromagnetic interaction problems with loss included; Calculation of the input impedance for coupled wires; Modeling of a thin wire arrays; Modeling of transmission lines and finite length wires, above or buried in a imperfect ground; Analysis of the safety aspects of the GSM base station radiation; 2.Development of the models directly in time domain Also oriented primaly on modeling wire structures.

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Current induced in overhead multiple transmmision lines – arbitrarily plane wave exication  =  0,  =  0 0 x y z h h x=L m /2 x=-L m /2 D mn x=-L n /2 =r0=0=r0=0 The geometry of the problem

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Governing equations For solving Pocklington type integral equation, developed finite element integral equation code is used.

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 RC approximation The influence of the imperfectly conducting lower medium is taken into account by means of the Fresnel plane wave reflection coefficient.

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Current distribution along two coupled wires over imperfect ground f=20MHz, ε r =10, σ=0.001mho/m, h=1m, D=0.5m, L=30m, a=0.15cm, φ=180°, θ=30°, α=0°

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Current distribution along two coupled wires over imperfect ground f=20MHz, ε r =10, σ=0.001mho/m, h=1m, D=0.5m, L=30m, a=0.15cm, φ=120°, θ=30°, α=0°

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Current distribution and near field calculation of a thin wire antenna array The near electric field radiated from the wire antenna array in the presence of the conductive half-space is evaluated using the previously calculated results for the current distribution along the antenna.

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Electric field near the antenna Expressions for the x, y and z components of the electric field at an arbitrary point in the air – Galerkin-Bubnov formulation

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Three wire antenna array E x component; xy plane Antenna in free space

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Three wire antenna array E x component; yz plane Antenna in free spaceAntenna over a lossy half-space

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Three wire antenna array E x component; xz plane Antenna in free spaceAntenna over a lossy half-space

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Transient current distribution along arbitrary thin wire array The geometry of the thin wire array

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 The Hallen space-time integral equation Space – time integral equation of the Hallen type is solved directly in the time domain.

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Three wire array excited by the voltage generator (antenna mode) Transient current induced at the center of the a) passive wire b) active wire a) b)

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Three wire array illuminated by the electromagnetic pulse (scatterer mode) Transient current induced at the point x=18m on the wire

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Interaction between human body and electromagnetic fields of the GSM base station In the investigation of the safety aspects of the GSM base station radiation the excitation function (incident field) in numerical modeling is defined by measurements.

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 ASSESMENT OF THE RF EXPOSURE LEVELS Metrics in exposure standards for RF range Frequency rangeBiomechanismDosimetric quant. VLF/LF ( kHz) Neuromuscular stimulation Current density in excitable tissues Intermediate RF (100kHz - 3GHz) Tissue heating Specific Absorption Rate (SAR) in W/kg Microwaves and mm (3 – 300 GHz) Surface heating Power Density in W/m 2

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Model of a human body Cylindrical model of a human body The Pocklington integral equation:

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 SAR calculation Disipated power density: King’s expresion for current density inside the body: Electric field inside body:

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Induced current along the human body Axial current distribution

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 SAR distribution along human body f=900MHz, E=2V/mf=915MHz, E=61,4V/m

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Compliance with the exposure limits Ground plan with the measurement points

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 View from the measuring point 3

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Measurement results and comparison with the exposure limits Measured electric field  E=1,531V/m Measured power density  S=6,21 W/m 2 National recommendation E limit =16,82V/m International and European recom. S limit =4,8W/m 2 Health risk measure (  E) 2 /E 2 limit = = 0,82 % = - 20,82 dBlimit  S/S limit = = 0,129 % = - 28,88 dBlimit

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Computational results and comparison with the exposure limits SAR[W/kg]Occupational exposure General public exposure Whole body avarage 0,40.08 Localized (head and trunk) 102 Localized (limbs) 204 PointE [V/m]SAR[μW/kg]

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Future work Investigations in the numerical procedure itself by: –Improving the already developed codes –Investigating and improving the convergence rate –Developing some new approaches Application of the newly developed models in frequency and especialy in time domain. The future work will be oriented to the:

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Conclusion Wire antenna theory applied to the EMI analysis and mitigation Interaction of wired networks and mobile telecommunication systems Interactions between transmission lines (telecommunication and power) Transients and lightning threats in communication systems Interaction of a human body with RF electromagnetic fields Numerical investigations of convergency problems and use of mesh reduced methods Some areas and focusing topics that are under investigation or will be in the scope of the future work and are related to the COST 286 action could be summarized as:

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Some of the relevant references [1] D.Poljak V.Roje: Finite Element Technique for Solving Time-Domain Hallen Integral Equation, Tenth International Conference on Antennas and Propagation, Proc. of ICAP'97, Conference Publication No436, IEE 1997, Edinburgh, UK, April 1997, pp [2] D.Poljak, V.Roje: Boundary element analysis of resitively loaded wire antenna immersed in lossy medium, 19 th World Conference on the Boundary Element Method, BEM 19, Proceedings BEM19, Rome, Italy, Sept 1997, pp [3] D.Poljak, V.Roje: Time-Domain Calculation of the Parameters of Thin Wire Antennas and Scatterers in Half- Space Configuration, IEE Proc. - Microw. Antennas Propag., Vol.145, No 1. pp 57-63, February 1998 [4] D.Poljak, V.Roje: Time Domain Modeling of Electromagnetic Field Compling to Transmission Lines, 1998 IEEE EMC Symposium Denver, USA, Aug. 1998, IEEE EMC Symposium Record Vol.2, pp [5] V.Roje, D.Poljak: Wire antenna Theory Applied to the Electromagnetic Interaction Problems with loss Included, Conference of software in telecommunications and computer networks SoftCOM'98, Split, Dubrovnik, Bari, Oct Proc. SoftCOM'98, pp [6] D. Poljak, V.Roje: Currents Induced in Human Body Exposed to the Power Electromagnetic Field, 20th Annual Int. Conference of the IEEE Engineering in Medicine and Biology Society, Hong Kong, 29. Oct , Proc. EMBS'98, pp [7] D. Poljak, A.Šarolić, V.Roje: Calculation of the foot current induced in human body exposed to electromagnetic pulse, Proc. of the 4 th EBEA Congress, Zagreb, Croatia, Nov.19-21, 1998, pp [8] D.Poljak, V.Roje: Transient Response of Coumpled Wires in a Half-Space Configuration, IEEE Int. Symposium on Electromagnetic Compatibility, Seatle, Washington, USA, Aug. 1999, pp

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Some of the relevant references [9] D.Poljak, C.Y. Tham, A.McCowen, V.Roje: Electromagnetic Pulse Excitation of Multiconductor Transmission Lines, International Conference on Electromagnetics in Advanced Applications, Proc. ICEAA'99, Turin, Italy, Sept. 1999, pp [10] D.Poljak, V.Roje: Induced Current and Voltages Along a Horizontal Wire Above a Lossy Ground, WIT Press, UK, Computational Mechanics Inc. Boundary Elements XXI, C.A. Brebbia, H.Power (ed), pp , [11] V.Roje, D.Poljak: Wire Antenna Model of the Human Body Exposed to the Low Frequency Electromagnetic Fields, AFRICON 5 th Conf. Cape Tow Sept/Oct Institute of Electrical and Electronics Engineers IEEE, Inc. 1999, Vol.2, pp [12] D.Poljak, V.Dorić, V.Roje, B.Burmaz: Modeling of the Lightning Return Stroke Current in the Frequency Domain, SoftCOM'99, Int. Conf. on Software in Telecommunication and Computer Networks, Split, Rijeka, Trieste, Venice, Oct pp [13] D.Poljak, E.K. Miller, C.Y. Tham, V. Roje:Time Domain Calculation of the Energy Stored in the Thin Wire Near Field, AP 2000, Millennium Conference on Antennas & Propagation, Davos April 2000, CD of AP 2000 (Complete Proc.) and Proceedings (Abstracts) Vol.1-Antennas pp 65 [14] D.Poljak, C.Y.Tham, A.Mc Cowen, V.Roje: Transient Analysis of Two Coupled Horizontal Wires Over a Real Ground, IEE Proc. - Microwaves Antennas Propagation, Vol.147, No 2, pp 87-94, April 2000 [15] D.Poljak, V.Roje, C.Y.Tham, A.McCowen: Time Domain Analysis of Thin Wire with Nonlinear Loads, presented at COST Action 261 Workshop on Computational Electromagnetics for Complex and Distributed Systems, Cagliari, Italy, May 2000, Proc. on CD and web [16] D. Poljak, C.Y. Tham, V. Roje, A. Šarolić: Time Domain Analysis of the Human Body Exposed to the EMP Excitation Using the Human Equivalent Antenna Model, 2000 IEEE AP-S International Symposium and USNC/URSI National radio Science Meeting, URSI 2000 Digest, Salt Lake City, USA, July 2000, pp 159

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Some of the relevant references [17] D. Poljak. V. Dorić, V. Roje: Boundary Element Modeling of Arbitrary Wire Configurations, 22nd International Conference on the Boundary Element Method, BEM 22, Cambridge, UK, Sept in Boundary Elements XXII, C.A.Brebbia, H.Power (editors), Series Advances in Boundary Elements, WIT Press, Southampton UK and Computational Mechanics Inc. USA, 2000, Vol.8, pp [18] D. Poljak, V. Dorić, V. Roje: Current Induced Along a Multiple Transmission Line Above a Lossy Half Space, 4th European Symposium on Electromagnetic Compatibility, Proc. EMC Europe 2000, Brugge, Belgium, Sept. 2000, pp [19] D.Poljak, L.Nagy, V.Dorić, C.Y.Tham, V.Roje: Frequency and Time Domain Analysis of Wire Antenna Arrays, Eleventh International Conference on Antenna and Propagation (ICAP 2001), UMIST, Manchester, UK, April Conf. Publication No. 480, Vol.I [20] D. Poljak, V. Roje: Transient Response of a Thin Wire Buried in a Real Ground, Proc. of the 2001 IEEE Antennas & Propagation Society International Symposium, July 2001, Boston USA, Vol.2, pp [21] D. Poljak, R. Lucić, V. Roje: Transient Analysis of Electromagnetic Field Coupling to Buried Cables, International Conference on Electromagnetics in Advanced Applications (ICEAA 01), Sept. 2001, Torino Italy, Proc. of the ICEAA 01, pp [22] K. Malarić, A. Šarolić, V. Roje, J. Bartolić, B. Modlic: Measured Distribution of Field in GTEM-Cell, IEEE Int. Symposium on Electromagnetic Compatibility, Montreal, Canada, Aug (Proc. on CD) [23] D. Poljak, V. Roje, F. Lattarulo, J. Petric, I. Gizdić: Time Domain Modeling of the Lightning Channel and Related Effects to Telecommunication Lines, SoftCOM 2001, Int. Conf. on Software, Telecommunication and Computer Networks, Oct. 2001, Split, Ancona, Bari, Dubrovnik, Vol.I, pp [24] D. Poljak, E. Miller, V. Roje Transient Analysis of a Single Transmission Line Above a Dielectric Half-Space, 2002 URSI – GA, Mastrict, August 2002

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Some of the relevant references [25] D. Poljak, V. Roje, A. Šarolić: Human Interaction with the Electromagnetic Field Radiated from a Cellular Base Station Antennas, Proc. EMC Europe 2002, Int. Symposium on Electromagnetic Compatibility, Sept. 2002, Sorrento, Italy, Vol.2, pp [26] A. Šarolić, B. Modlic, V. Roje, D. Poljak, P. Pavić: Shipboard RF Equipment Radiation Measurements and Hazard Analysis,Proc. EMC Europe 2002, Int. Symposium on Electromagnetic Compatibility, Sept. 2002, Sorrento, Italy, Vol. 2, pp [27] D. Poljak, I. Gozdić, V. Roje: Plane Wave Coupling to Finite Length Cables Buried in a Lossy Ground, Engineering Analysis with Boundary Elements 26 (2002), pp [28] V. Dorić, D. Poljak, V. Roje: Electromagnetic Field Coupling to Multiple Finite Length Transmission Line Above an Imperfect Ground, The 2003 IEEE International Symposium on Electromagnetic Compatibility, Istambul Turkey, May 2003 [29] V. Roje, D. Poljak, A. Šarolić: Safety Aspects of the GSM Base Station Radiation Concerning Human Health, The 2003 IEEE International Symposium on Electromagnetic Compatibility, Istambul Turkey, May 2003 [30] S. Antonijević. D. Poljak, C. Y. Tham, V. Roje: Time Domain Calculation of the Transient Current Distribution Along a Thin Wire Antenna Array, BEM 25, Sept. 2003, Split, Croatia in Boundary Elements XXV, C.A. Brebbia, D. Poljak, V. Roje (editors), Advances in Boundary Elements Series, Vol.18, WIT Press, Southampton UK and Computational Mechanics Inc., Boston USA 2003, pp [31] S. Antonijević, D. Poljak, V. Roje: Time Domain Calculation of the Scattering on a Thin Wire Antenna Array, SoftCOM 2003, Int. Conf. on Software, Telecommunication and Computer Networks, Oct. 2003, Split, Venice, Ancona, Dubrovnik, Croatia, Italia [32] D. Poljak, E. K. Miller, C. Y. Tham: Time-Domain Energy Measures for Thin-Wire Antennas and Scatterers, IEEE Antennas and Propagatione Magazine, 44 pp 87-95

COST 286 Workshop on EMC in Diffused Communication Systems, Wroclow 17/18 September 2003 Some of the relevant references [33] D. Poljak, C. Y. Tham, O. Gandhi, A. Šarolić: Human Equivalent Antenna Model for Transient Electromagnetic Radiation, IEEE Transactions on EMC 45, pp [34] D. Poljak: Human exposure to the electromagnetic field, Southampton-Boston: WIT Press, 2003