BS EN 50383:2010 Incorporating June 2013 BS EN corrigendum 50383:2010 BSI Standards Publication Basic standard for the calculation and measurement of electromagnetic field strength and SAR related to human exposure from radio base stations and fixed terminal stations for wireless telecommunication systems (110 MHz - 40 GHz) BS EN 50383:2010 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 50383:2010, incorporating corrigendum June 2013 It supersedes BS EN 50383:2002 which is withdrawn The UK participation in its preparation was entrusted to Technical Committee GEL/106, Human exposure to low frequency and high frequency electromagnetic radiation A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2013 Published by BSI Standards Limited 2013 ISBN 978 580 83711 ICS 13.280; 17.220.20; 33.070.01 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 September 2010 Amendments/corrigenda issued since publication Date Text affected 31 July 2013 Implementation of CENELEC corrigendum June 2013: clause renumbered BS EN 50383:2010 EN 50383 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM June 2010 Incorporating corrigendum June 2013 Supersedes EN 50383:2002 ICS 17.220.20; 33.070.01 English version Basic standard for the calculation and measurement of electromagnetic field strength and SAR related to human exposure from radio base stations and fixed terminal stations for wireless telecommunication systems (110 MHz - 40 GHz) Norme de base pour le calcul et la mesure des champs électromagnétiques et SAR associés l'exposition des personnes provenant des stations de base radio et des stations terminales fixes pour les systèmes de radiotélécommunications (110 MHz - 40 GHz) Grundnorm für die Berechnung und Messung der elektromagnetischen Feldstärke und SAR in Bezug auf die Sicherheit von Personen in elektromagnetischen Feldern von Mobilfunk-Basisstationen und stationären Teilnehmergeräten von schnurlosen Telekommunikationsanlagen (110 MHz bis 40 GHz) This European Standard was approved by CENELEC on 2010-06-01 CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels © 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members Ref No EN 50383:2010 E BS EN 50383:2010 EN 50383:2010 EN 50383:2010 BS EN 50383:2010 –2– -2- Foreword This European Standard was prepared by the Technical Committee CENELEC TC 106X, Electromagnetic fields in the human environment It was submitted to the Unique Acceptance Procedure as a draft amendment and approved by CENELEC as a new edition on 2010-06-01 This European Standard supersedes EN 50383:2002 The main changes compared to EN 50383:2002 are as follows (minor changes are not listed): − the frequency range has been extended to cover 300 MHz to GHz now, was 300 MHz to GHz before − the references to EN 50361 have been updated with referring to EN 62209-2:2010 now and paragraphs have been removed, that are covered by EN 62210-2 − the former Annex A "Boundaries between field regions" has been replaced by an Annex "Considerations for using far-field method" Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN and CENELEC shall not be held responsible for identifying any or all such patent rights The following dates were fixed: − latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2011-06-01 − latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2013-06-01 –3– -3- BS EN 50383:2010 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 Scope This basic standard applies to radio base stations and fixed terminal stations for wireless telecommunication systems as defined in Clause 4, operating in the frequency range 110 MHz to 40 GHz The objective of the standard is to specify, for such equipment, the method for assessment of compliance distances according to the basic restrictions (directly or indirectly via compliance with reference levels) related to human exposure to radio frequency electromagnetic fields Normative references The following referenced documents are indispensable for the application of this document For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN 62209-2:2010, Human exposure to radio frequency fields from hand-held and body-mounted wireless communication devices – Human models, instrumentation, and procedures – Part 2: Procedure to determine the specific absorption rate (SAR) for mobile wireless communication devices used in close proximity to the human body (frequency range of 30 MHz to GHz ISO/IEC 17025:1999, General requirements for the competence of testing and calibration laboratories ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) Council Recommendation 1999/519/EC of 12 July 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz) (Official Journal L 197 of 30 July 1999) International Commission on Non-Ionizing Radiation Protection (1998), Guidelines for limiting exposure in time-varying electric, magnetic, and electromagnetic fields (up to 300 GHz) Health Physics 74, 494-522 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 BS EN 50383:2010 –4– -4- Physical quantities, units and constants 3.1.1 Quantities The internationally accepted SI-units are used throughout the standard Quantity Symbol Unit Dimensions Current density J ampere per square metre A/m Electric field strength E volt per metre V/m Electric flux density D coulomb per square metre C/m Electric conductivity σ siemens per metre S/m Frequency f hertz Hz Magnetic field strength H ampere per metre 2 A/m Magnetic flux density B tesla (Vs/m ) T Mass density ρ kilo per cubic metre kg/m Permeability µ henry per metre H/m Permittivity ε farad per metre F/m Specific absorption rate SAR watt per kilogram W/kg Wavelength λ metre m Temperature T kelvin K 3.1.2 Constants Physical constant Magnitude Speed of light in a vacuum c 2,997 x 10 m/s Permittivity of free space ε0 8,854 x 10 Permeability of free space µ0 π x 10 H/m Impedance of free space η0 120 π (approx 377) Ω -12 F/m -7 Terms and definitions 4.1 antenna device that serves as a transducer between a guided wave (e.g coaxial cable) and a free space wave, or vice versa –5– -5- BS EN 50383:2010 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 4.2 average (temporal) absorbed power Pavg the time-averaged rate of energy transfer defined by: _ Pavg t = P(t)dt t − t1 ∫t (1) where t1 and t2 are the start and stop time of the exposure The period t2 – t1 is the exposure duration time 4.3 averaging time tavg the appropriate time over which exposure is averaged for purposes of determining compliance with the limits 4.4 base station BS in this standard, the term “Base Station” (BS) covers radio base stations as well as fixed terminal stations intended for use in wireless telecommunications networks 4.5 basic restriction restrictions on exposure to time-varying electric, magnetic and electromagnetic fields that are based directly on established health effects In the frequency range from 110 MHz to 10 GHz, the physical quantity used is the specific absorption rate Between 10 GHz and 40 GHz, the physical quantity is the power density 4.6 compliance boundary volume outside which any point of investigation is deemed to be compliant Outside the compliance boundary, the exposure levels not exceed the basic restrictions irrespective of the time of exposure 4.7 conductivity σ ratio of the conduction-current density in a medium to the electric field strength Conductivity is expressed in units of siemens per metre (S/m) 4.8 continuous exposure exposure for a duration exceeding the averaging time 4.9 duty factor (duty cycle) ratio of the pulse duration to the pulse period of a periodic pulse train A duty factor of unity corresponds to continuous-wave operation 4.10 electric field strength E the magnitude of a field vector at a point that represents the force (F) on a positive small charge (q) divided by the charge: E= F q Electric field strength is expressed in units of volt per metre (V/m) (2) BS EN 50383:2010 EN 50383:2010 EN 50383:2010 BS EN 50383:2010 –6– -6- 4.11 electric flux density D the magnitude of a field vector that is equal to the electric field strength (E) multiplied by the permittivity ( ε ): D = εE (3) Electric flux density is expressed in units of coulomb per square metre (C/m ) 4.12 equipment under test EUT device (such as transmitter, base station or antenna as appropriate) that is the subject of the specific test investigation being described 4.13 fixed terminal station a fixed terminal station, usually associated with the user, comprises the hardware, including transceivers, necessary to transmit and receive radio signals Fixed terminal stations with integrated antennas, fixed terminal stations with connectors for external antennas and fixed terminal stations intended for use with external antennas not supplied by the same manufacturer are covered In this standard, the fixed terminal stations are covered by the term “base station” 4.14 intrinsic impedance (of free space η η0 ) the ratio of the electric field strength to the magnetic field strength of a propagating electromagnetic wave The intrinsic impedance of a plane wave in free space is 120 π (approximately 377) ohm 4.15 isotropy deviation of the measured value with regard to various angles of incidence of the measured signal In this document, it is defined for incidences covering a hemisphere centred at the tip of the probe, with an equatorial plane normal to the probe and expanding outside the probe The axial isotropy is defined by the maximum deviation of the measured quantity when rotating the probe along its main axis with the probe exposed to a reference wave with normal incidence with regard to the axis of the probe The hemispherical isotropy is defined by the maximum deviation of the measured quantity when rotating the probe along its main axis with the probe exposed to a reference wave with varying angles of incidences with regard to the axis of the probe in the half space in front of the probe 4.16 linearity maximum deviation over the measurement range of the measured quantity from the closest linear reference curve defined over a given interval 4.17 loss tangent the loss tangent tan(δ) is the ratio of the imaginary part of the complex dielectric constant of a material to its real part 4.18 magnetic flux density B the magnitude of a field vector that is equal to the magnetic field strength H multiplied by the permeability (µ ) of the medium: (4) B=µ H Magnetic flux density is expressed in units of tesla (T) –7– -7- BS EN 50383:2010 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 4.19 magnetic field strength H the magnitude of a field vector in a point that results in a force ( F ) on a charge velocity v : F = q (v ì H ) q moving with the (5) The magnetic field strength is expressed in units of ampere per metre (A/m) 4.20 multi-band a multi-band equipment is operating in more than one frequency band, e.g GSM 900 and GSM 1800 4.21 multi-mode a multi-mode equipment is operating with various radio communication systems, e.g GSM and DECT 4.22 permeability µ the magnetic permeability of a material is defined by the magnetic flux density B divided by the magnetic field strength H: µ= where µ B H (6) is the permeability of the medium expressed in Henry per metre (H/m) 4.23 permittivity ε the property of a dielectric material (e.g biological tissue) defined by the electrical flux density D divided by the electrical field strength E: ε= D E (7) The permittivity is expressed in units of farad per metre (F/m) 4.24 phantom in this context, a phantom is a simplified representation or a model similar in appearance to the human anatomy and composed of materials with electrical properties similar to the corresponding tissues 4.25 point of investigation POI the location in space at which the value of E-field, H-field, Power flux density or SAR is evaluated This location is defined in Cartesian, cylindrical or spherical co-ordinates relative to the reference point on the EUT 4.26 power flux density S power per unit area normal to the direction of electromagnetic wave propagation 4.27 radio base station a radio base station, usually associated with the network, comprises the hardware, including transceivers, necessary to transmit and receive radio signals Radio base stations with integrated antennas, radio base stations with connectors for external antennas and radio base stations intended for use with external antennas not supplied by the same manufacturer are covered BS EN 50383:2010 EN 50383:2010 EN 50383:2010 BS EN 50383:2010 –8– -8- In this standard, the radio base stations are covered by the term “base station” 4.28 radio frequency RF for purposes of these safety considerations, the frequency range of interest is 110 MHz to 40 GHz 4.29 relative permittivity εr the ratio of the permittivity of a dielectric material to the permittivity of free space i.e εr = ε ε0 (8) 4.30 root-mean-square rms value obtained by taking the square root of the average of the square of the value of the periodic function taken throughout one period 4.31 root-sum-square rss the rss value or the Hermitian magnitude of a vector v is obtained by the square root of the sum of the squared rms values of all three orthogonal components of vector v The rss value is proportional to the joule heating and can be quite different from the rms amplitude of vector v 4.32 scanning system the scanning system is the positioning system capable of placing the measurement probe at the specified positions 4.33 specific absorption rate SAR the time derivative of the incremental energy (dW) absorbed by (dissipated in) an incremental mass (dm) contained in a volume element (dV) of given mass density ( ρ ) SAR = d dW d dW = dt dm dt ρ dV SAR is expressed in units of watt per kilogram (W/kg) (9) BS EN 50383:2010 50383:2010 BS EN EN 50383:2010 – 70 – EN 50383:2010 - 68 - C.2.2 Averaging scheme and maximum finding C.2.2.1 Introduction According to ICNIRP Guidelines [12] the averaging volume shall be chosen as 10 g of contiguous tissue However, a cube may be used [13] The cubic volumes over which the SAR measurements are averaged after extrapolation and interpolation have to be close to the phantom surface in order to include the highest values of local SAR Since the phantom shape is rectangular, the cube will be oriented parallel to the surface of the phantom Then the way to choose the points for averaging will be investigated before a method for the evaluation of uncertainty is described C.2.2.2 Method of averaging The main objective is to obtain an averaging mass of 10 g To achieve this, SAR points may be added layer by layer to make the cube grow until its mass exceeds 10 g Then, the corresponding absorbed power may be deduced by linear interpolation C.2.2.3 Averaging scheme & Maximum finding Uncertainty Assessment The peak localised SAR will occur at the inner surface of the phantom, so the highest spatially averaged SAR should occur in a cubic tissue volume at the surface of the phantom It therefore follows that high-resolution measurement scans should be centred on the peak localised SAR determined from a scan of the interior surface of the phantom This scanned surface should extend laterally at least twice the linear dimension of the tissue cube used for mass averaging Computer controlled algorithms should be used to determine the highest SAR according to the local SAR gradients in the mass averaging cube To verify the accuracy of this maximum finding process and evaluate the related uncertainty, two sets of 3D reference data have to be used These data sets are given by the two analytical functions defined in C.2.1.4 The reference data have been collected with a millimetric spatial resolution to avoid the need for any extrapolation or interpolation processes The reference data sets include target values for their maximum mass averaged SAR and these shall be compared with the maximum mass averaged SAR yielded by the averaging and maximum finding schemes under evaluation The relative uncertainty shall be evaluated using: U max finding % = 100 SARmax estimated − SARmax ref SARmax ref – 71 – - 69 - C.3 BS EN 50383:2010 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 Simplified performance checking (normative) C.3.1 Phantom set-up The set-up uses a flat phantom with a dipole antenna held at a specified distance The following phantom specifications are necessary to guarantee a high repeatability in the measurement: - the phantom must be at least 0,75 times the wavelength in air, in both length and width This gives a maximum difference below % for the 10 g averaged SAR with respect to an infinitely large flat phantom; the depth of liquid in the phantom shell must be greater than twice the wavelength in liquid This depth is estimated to be approximately 100 mm This guarantees negligible errors due to standing waves at the liquid surface; the phantom shell shall be made of low conductivity material The thickness of the bottom of the phantom shall be less than 10 mm, although the sides may be thicker; the same liquids that are required for compliance testing with the anthropomorphic phantom shall be used, see 7.2.2.2; the flat phantom shall be mounted in a structure made of a rigid material of low relative permittivity and low conductivity Metallic parts must be avoided in the vicinity of the structure C.3.2 Dipole source The dipole shall be positioned and centred below the phantom, parallel to the longest side of the phantom A low conductivity and low relative permittivity spacer on the dipole may be used to guarantee the correct distance between the dipole top surface and the phantom bottom surface The distance between the liquid surface and the dipole centre is specified within ± 0,2 mm for each test frequency The dipole shall have < - 20 dB return loss in the set-up to reduce the uncertainty in the power reading For the dipoles described below, the distance d is given by: − dipoles for 110 MHz to 000 MHz: d = 15 mm ± 0,2 mm − dipoles for 000 MHz to 000 MHz: d = 10 mm ± 0,2 mm The definition of d is the distance from the liquid surface to the dipole’s central axis, as shown in Figure C.1 C.3.3 Dipole Input Power Measurement The uncertainty of the input power to the dipole must be as small as possible This requires a sophisticated set-up with directional couplers and power monitoring during the system check The recommended set-up is described below in Figure C.1 BS EN 50383:2010 50383:2010 BS EN EN 50383:2010 – 72 – EN 50383:2010 - 70 - 3D Scanning system d Field probe Flat Phantom Dipole Signal Generator Dir.Coupler Amp Low Pass 3dB Cable Att3 x Att1 PM1 Att2 Load PM2 Figure C.1 – Simplified Performance Checking Set-up First, the power meter PM1 is connected to the cable and it measures the forward power at the location of the dipole connector (X) The signal generator is adjusted for the desired forward power at the dipole connector (taking into account the (Att1) value) and the power meter PM2 is read at that level Then after connecting the cable to the dipole, the signal generator is readjusted for the same reading at the power meter PM2 If the signal generator does not allow a setting in 0,01 dB steps, the remaining difference at PM2 must be taken into consideration The requirements for the components are: − the signal generator and amplifier should be stable (after warm-up) The forward power to the dipole should be high enough to avoid the influence of measurement noise If the signal generator can deliver 15 dBm or more, an amplifier is generally not necessary Some high power amplifiers should not be operated at a level far below their maximum output power level, e.g a 100 W power amplifier operated at 250 mW output can be quite noisy An attenuator between the signal generator and amplifier is recommended to protect the amplifier input; − the low pass filter after the amplifier reduces the effect of harmonics and noise from the amplifier For most amplifiers in normal operation the filter is not necessary; − the attenuator after the amplifier improves the source matching and the accuracy of the power sensor (see power meter manual) It can also be used to make the amplifier operate at its optimal output level for noise and stability In a set-up without directional coupler, this attenuator should be at least 10 dB; − the directional coupler (recommended - 20 dB) is used to monitor the forward power and adjust the signal generator output for constant forward power A medium quality coupler is sufficient because the loads (dipole and power head) are both well matched (If the set-up is used for more reflective loads, a high quality coupler with respect to directivity and output matching is necessary to avoid additional errors.); − the power meter PM2 should have a low drift and a resolution of 0,01 dBm, but otherwise its accuracy has no impact on the power setting (Calibration is not required.); – 73 – - 71 - BS EN 50383:2010 EN BS50383:2010 EN 50383:2010 EN 50383:2010 − the power meter PM1 and attenuator Att1 must be high quality components They should be calibrated, preferably together The attenuator (- 10 dB) improves the accuracy of the power reading (Some higher power heads come with a built-in calibrated attenuator.) The exact attenuation of the attenuator at the test frequency must be known; − use the same power level for the power set-up with power meter PM1 as for the actual measurement to avoid linearity and range switching errors in the power meter PM2 If the system check is performed at various power levels, the power setting procedure at each level; − the dipole must be connected directly to the cable at location “X” If the power meter has a different connector system, use high quality adaptors C.3.4 Simplified performance checking procedure The simplified performance checking includes all measurement procedures used also for compliance tests The 10 g averaged SAR value is normalised to the target input power of the dipole and compared to the target 10 g value The acceptable tolerance must be determined for each system It is evaluated from the uncertainty of all involved system components and the uncertainty of the dipole input power C.4 References [1] PW Fieguth & al, "Multi-resolution optimal interpolation and statistical analysis of TOPEX/POSEIDON satellite altimetry", IEEE trans Geosci Remote Sensing vol 33 pp 280-292 Mar 1995 [2] P Lancaster, K Salkauska, "Curve and surface fitting: an introduction", New York Academic 1986 [3] EN 62209-2:2010, Human exposure to radio frequency fields from handheld and body-mounted wireless communication devices – Human models, instrumentation, and procedures – Part 2: Procedure to determine the specific absorption rate (SAR) for mobile wireless communication devices used in close proximity to the human body (frequency range of 30 MHz to GHz) [4] PJSG Ferreira, "Non Iterative and Fast Iterative Methods for Interpolation and Extrapolation", IEEE trans Signal Processing Vol 41 pp 3278-3282 Nov 1994 [5] Christ A, Klingenböck A, Samaras T, Goiceanu C, and Kuster N, “The dependence of electromagnetic far-field absorption on body tissue composition in the frequency range from 300 MHz to GHz”, IEEE Transactions on Microwave Theory and Techniques, vol 54, no 5, pp 2188–2195, May 2006 [6] Christ A, Samaras T, Klingenböck A, and Kuster N, “Characterization of the electromagnetic near-field absorption in layered biological tissue in the frequency range from 30 MHz to GHz”, Physics in Medicine and Biology, vol 51, no 19, pp 4951–4965, October 2006 [7] Aline Pradier, Abdelhamid Hadjem ,David Lautru, Azeddine Gati, Man-Faï Wong, Victor Fouad Hanna,Joe Wiart "Evaluation of the SAR induced in a multilayer biological structure and comparison with SAR in homogeneous tissues" Annals of telecommunication (2008) 63: 79-86 [8] C Ford & DM Etter, "Wavalet basis reconstruction of non uniform sampled data", IEEE Trans Circuits and System II: Analog and Digital Signal Processing vol 45 n)8 pp 1165 1168 Aug 1998 [9] KF Ustuner & LA Ferrai, "Discrete Splines and spline filter", IEEE trans Circuits and Systems vol 39 n°7 pp 417 422 jul 1991 [10] "NUMERICAL RECIPES IN C", Cambridge University Press, 1992 [11] M Brishoual, C Dale, J Wiart and J Citerne, “Methodology to interpolate and extrapolate SAR measurements in a volume in dosimetric experiment”, IEEE trans on EMC Vol 43 n°3 pp 382-389 August 2001 BS EN 50383:2010 50383:2010 BS EN EN 50383:2010 EN 50383:2010 – 74 – - 72 - [12] ICNIRP Guidelines, "Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields (up to 300 GHz)", Health Physics Volume 74 Number 4, April 1998 [13] Body weight data from the U.S National Center for Health statistics http://www.cdc.gov/nchs/about/major/nhanes/growthcharts/charts.htm [14] L Hamberg, N Lovehagen, M Siegbahn, and C Tornevik, “A method for determination of RF exposure compliance for pico cell base stations by SAR measurements in a flat phantom,” in Proc IEEE Int AP-S Symp., vol 2, Columbus, OH, Jun 2003, pp 1009–1012 BS EN 50383:2010 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 – 75 – - 73 - Annex D (informative) Considerations on calculation methods D.1 Example related to the synthetic method This Clause describes an example for a vertical collinear array z E2(r1) r3 r2 r1 r1 P r2 E2(r2) r3 E2(r3) Figure D.1 – Base Station Antenna considered as a sum of small separate sources If the antenna patches are vertically polarized: − the vector components of E from each antenna patch will not be exactly parallel on bore sight The actual resultant E field value at a point will be slightly less than that derived from the above formula, so compliance is still demonstrated; − the magnetic field strength can be obtained from the value of E in this formula divided by the free space impedance Since the H vectors are parallel, this result will be more accurate than the derived value of E If the antenna patches are horizontally polarized: − the vector components of E from each antenna patch will be exactly parallel on bore sight while those of H are not In this case, a small over-estimation of the H-field will occur if it is obtained by assuming a free-space relationship with E so compliance for E & H is still demonstrated If the antenna patches are cross-polarized: − the vector components of E & H from each antenna patch will not be exactly parallel on bore sight The actual resultant E field value at a point will be slightly less than that derived from the above formula, so compliance for E & H is still demonstrated − hence if the power flux density, S, is then obtained by the multiplication of E and H, in any case this is conservative BS EN 50383:2010 EN 50383:2010 EN 50383:2010 BS EN 50383:2010 D.2 – 76 – - 74 - Reactive near-field region This region is defined as in 8.2 Full-wave methods are necessary to determine the E-field, H-field or SAR These procedures are based on solving Maxwell’s equations in time or frequency domain using detailed-segmented models The more detailed the image, the better the accuracy of the field Dependent on the numerical implementation the following techniques fulfil these requirements: − Finite Difference Time Domain Method (FDTD); − Method of Moments (MOM); − Finite Elements Method (FEM); − Transmission Line Matrix Method (TLM) D.3 Considerations on the uncertainty in the case of calculation The objective of EM field simulation in the context of exposure assessment is to find the maximum of the absolute value of the electric or magnetic field strength and the power density in a given volume Thus, it is possible to find a closed surface around the field source which ensures that the absolute value of these parameters is below a given exposure limit In principle, three different sources of uncertainty can be identified: − deviation between the true antenna and the simulated antenna; − those related to model approximating the physics, including the use of the correct model for the field regions given in Annex A; − those related to segmentation and discretisation of the simulated antenna and formulas Considering the second point, one has to distinguish between different tools − For all methods listed under “Full wave analysis” the error will be very small if an appropriate segmentation and discretisation is used and the properties of the body are accurately simulated The values have to be calculated in a rectangular volume with a depth and width of 4*λ and a height defined by the antenna height plus 4*λ The increment should be less than λ/3 in the x-, y-, and z-direction For FDTD the increment should be less than λ/10, in the x-, y- and z-direction and should be gradually reduced to assess discretisation errors which shall be reported [1], [2] − In contrast, the cylindrical wave approach can have a significant error; it is liable to overestimate the field strength − If the radiating near-field calculation methods were used at a distance of λ/4 the actual power flux density may be higher (Annex A) If segmentation is improved and quantisation made finer to such an extent that further improvements does not change the result significantly, errors of the third kind will be negligible To get a good estimate for the errors related to the modelling of the antenna the electric and magnetic field strength may be determined by measuring these field quantities Remembering that measurement has its own errors The difference is then defined as: ediff = max || Xmeas (r) || - max || Xcalc(r) || With X standing for either: electric field strength, magnetic field strength or power density For exposure assessment overestimation is allowed because the true value is liable to be well below the calculated value – 77 – - 75 - D.4 BS EN 50383:2010 EN 50383:2010 BS EN 50383:2010 EN 50383:2010 References [1] Allen Taflove, Computational Electrodynamics: The Finite-Difference Time-Domain Method, Artech House Publishers, 1996 [2] B Archambeault, O M Ramahi, C Brench, EMI/EMC Computational Modeling Handbook, Kluwer Academic Publishers, 1998 [3] Z.Altman &al “efficient models for base station antenna for dosimetric analysis” submitted to IEEE trans on EMC [4] M Bizzi, P Gianola “ Electromagnetic fields radiated by GSM antennas”Electronics letters, 27th May 1999, Vol 35, No 11 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 BS EN 50383:2010 – 78 – - 76 - Annex E (informative) Compliance boundary examples E.1 Examples of simple compliance boundary Parallelepipedic boundary Dup Dside Drear Dfront Dside Ddown Dfront Drear x Dside Dup Ddown Figure E.1 – Distances parameters definition BS EN 50383:2010 EN BS50383:2010 EN 50383:2010 – 79 – - 77 - EN 50383:2010 The parallelepiped should be described by Dfront, Drear, Dside, Dup, Ddown The report shall estimate the value of these distances over the frequencies of test, for a set of given input powers comprising for instance 1, 2, 5, 10, 20, 50 W The result shall be summarised in a table as the following: Table E.1 – Summarised results Dfront Input Power 1W 2W … Drear Dside Dup Ddown Cylindrical boundary D up radius D down Figure E.2 – Distances parameters definition The cylinder should be described by Radius, Dup, Ddown The report shall estimate the value of these distances over the frequencies of test, for a set of given input powers comprising for instance 1, 2, 5, 10, 20, 50 W The result shall be summarised in a table as the following: Table E.2 – Summarised results Input Power 1W 2W … E.2 Radius Dup Ddown Complex compliance boundary As shown in Figure E.3, the compliance boundary should be complex In this case, the shape should be accurately described (e.g Z = function(X,Y)) The report shall estimate the shape over the frequencies of test, for a set of given input powers comprising for instance 1, 2, 5, 10, 20, 50 W BS EN 50383:2010 EN 50383:2010 EN 50383:2010 BS EN 50383:2010 – 80 – - 78 - z z = f(x,y) y x Figure E.3 – Example of complex compliance boundary – 81 – - 79 - Annex F (informative) NIST 18 term error model BS EN 50383:2010 BS EN 50383:2010 EN 50383:2010 EN 50383:2010 This page deliberately left blank This page deliberately left blank NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards Institution (BSI) BSI is the national body responsible for preparing British Standards and other standards-related publications, information and services BSI is incorporated by Royal Charter British Standards and other standardization products are published by BSI Standards Limited About us Revisions We bring together business, industry, government, consumers, innovators and others to shape their combined experience and expertise into standards -based solutions Our British Standards and other publications are updated by amendment or revision The knowledge embodied in our standards has been carefully assembled in a dependable format and refined through our open consultation process Organizations of all sizes and across all sectors choose standards to help them achieve their goals Information on standards We can provide you with the knowledge that your organization needs to succeed Find out more about British Standards by visiting our website at bsigroup.com/standards or contacting our Customer Services team or Knowledge Centre Buying standards You can buy and download PDF versions of BSI publications, including British and adopted European and international standards, through our website at bsigroup.com/shop, where hard copies can also be purchased If you need international and foreign standards from other Standards Development Organizations, hard copies can be ordered from our Customer Services team Subscriptions Our range of subscription services are designed to make using standards easier for you For further information on our subscription products go to bsigroup.com/subscriptions With British Standards Online (BSOL) you’ll have instant access to over 55,000 British and adopted European and international standards from your desktop It’s available 24/7 and is refreshed daily so you’ll always be up to date You can keep in touch with standards developments and receive substantial discounts on the purchase price of standards, both in single copy and subscription format, by becoming a BSI Subscribing Member PLUS is an updating service exclusive to BSI Subscribing Members You will automatically receive the latest hard copy of your standards when they’re revised or replaced To find out more about becoming a BSI Subscribing Member and the benefits of membership, please visit bsigroup.com/shop With a Multi-User Network Licence (MUNL) you are able to host standards publications on your intranet Licences can cover as few or as many users as you wish With updates supplied as soon as they’re available, you can be sure your documentation is current For further information, email bsmusales@bsigroup.com BSI Group Headquarters 389 Chiswick High Road London W4 4AL UK We continually improve the quality of our products and services to benefit your business If you find an inaccuracy or ambiguity within a British Standard or other BSI publication please inform the Knowledge Centre Copyright All the data, software and documentation set out in all British Standards and other BSI publications are the property of and copyrighted by BSI, or some person or entity that owns copyright in the information used (such as the international standardization bodies) and has formally licensed such information to BSI for commercial publication and use Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means – electronic, photocopying, recording or otherwise – without prior written permission from BSI Details and advice can be obtained from the Copyright & Licensing Department Useful Contacts: Customer Services Tel: +44 845 086 9001 Email (orders): orders@bsigroup.com Email (enquiries): cservices@bsigroup.com Subscriptions Tel: +44 845 086 9001 Email: subscriptions@bsigroup.com Knowledge Centre Tel: +44 20 8996 7004 Email: knowledgecentre@bsigroup.com Copyright & Licensing Tel: +44 20 8996 7070 Email: copyright@bsigroup.com