1、 International Telecommunication Union ITU-T K.61TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2008) SERIES K: PROTECTION AGAINST INTERFERENCE Guidance on measurement and numerical prediction of electromagnetic fields for compliance with human exposure limits for telecommunication installation
2、s Recommendation ITU-T K.61 Rec. ITU-T K.61 (02/2008) i Recommendation ITU-T K.61 Guidance on measurement and numerical prediction of electromagnetic fields for compliance with human exposure limits for telecommunication installations Summary Recommendation ITU-T K.61 helps telecommunication operato
3、rs to verify compliance with exposure standards promulgated by local or national authorities. This Recommendation gives guidance on measurement methods that can be used to achieve a compliance assessment. It also provides guidance on the selection of numerical methods suitable for exposure predictio
4、n in various situations. Source Recommendation ITU-T K.61 was approved on 29 February 2008 by ITU-T Study Group 5 (2005-2008) under Recommendation ITU-T A.8 procedure. Keywords RF exposure, RF safety. ii Rec. ITU-T K.61 (02/2008) FOREWORD The International Telecommunication Union (ITU) is the United
5、 Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendat
6、ions on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approv
7、al of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administratio
8、n“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance w
9、ith the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is requi
10、red of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellect
11、ual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. How
12、ever, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the p
13、rior written permission of ITU. Rec. ITU-T K.61 (02/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Terms and definitions . 2 4 Abbreviations and acronyms 3 5 General principles. 4 5.1 Quantities being measured . 4 5.2 Typical situations 4 6 Technical considerations 5 6.1 Averaging . 5 6.2 Quant
14、ities 5 6.3 Field regions . 5 6.4 Shadowing and scattering. 7 6.5 Variability of the source . 7 7 Measurements. 8 7.1 Measurement instrumentation 8 7.2 Evaluation of measurement uncertainties. 11 7.3 Probe selection 11 7.4 Procedures 12 7.5 Safety precautions 12 7.6 Field region. 12 7.7 Multiple sou
15、rces . 12 7.8 Time and spatial variability 12 8 Compliance with the limit: measurement results processing . 13 8.1 Identification of individual sources 13 8.2 Intermittent sources 14 8.3 Base stations for radio-mobile systems 14 Appendix I Calculation methods. 16 I.1 General . 16 I.2 Methods descrip
16、tion . 16 I.3 Other near-field models 17 I.4 Practical problems 18 Appendix II Identification and measurement of the main source of radiation . 19 II.1 Treatment of non-conformities Exceeding the exposure limits 19 II.2 Confirmation measurement 19 Bibliography. 20 iv Rec. ITU-T K.61 (02/2008) Introd
17、uction This Recommendation helps telecommunication operators to verify compliance with exposure standards promulgated by local or national authorities. Recommendation ITU-T K.52 provides indications on the need to perform an exposure assessment for a telecommunication installation. The assessment is
18、 based on the evaluation of the electromagnetic field and on accessibility considerations. The electromagnetic evaluation can be carried out by measurement or numerical prediction. This Recommendation defines tools, methods and procedures that can be used to achieve a compliance assessment. The comp
19、liance with radio-frequency exposure standards can be achieved by measurement of electromagnetic field strength, provided that calibrated instruments are used and measurement uncertainty is correctly expressed. Rec. ITU-T K.61 (02/2008) 1 Recommendation ITU-T K.61 Guidance on measurement and numeric
20、al prediction of electromagnetic fields for compliance with human exposure limits for telecommunication installations 1 Scope This Recommendation deals with measurements used for radio-frequency electromagnetic field strength evaluation to verify that human exposure limits are not exceeded by electr
21、omagnetic fields produced by telecommunication installations in the frequency range 9 kHz to 300 GHz. Also, this Recommendation gives guidance on computational methods that can be used to achieve a compliance assessment. Contact current exposure due to conductive objects irradiated by electromagneti
22、c field is not covered in this Recommendation. The exposure due to the use of mobile handsets or other radiating devices used in close proximity to the human body is not covered. Also, the exposure due to the use of cordless telephone systems and stationary sets intended for the use in wireless tele
23、communication networks (e.g., DECT, WLAN, Bluetooth, etc.) is not covered. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated
24、were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recomme
25、ndations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T K.52 Recommendation ITU-T K.52 (2000), Guidance on complying with limits for human exposure to electromagnetic fields. ITU-T K.70
26、 Recommendation ITU-T K.70 (2007), Mitigation techniques to limit human exposure to EMFs in the vicinity of radiocommunication stations. ITU-R BS.1698 Recommendation ITU-R BS.1698 (2005), Evaluating fields from terrestrial broadcasting transmitting systems operating in any frequency band for assessi
27、ng exposure to non-ionizing radiation. EN 50383 CENELEC EN 50383:2002, 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).
28、EN 50400 CENELEC EN 50400:2006, Basic standard to demonstrate the compliance of fixed equipment for radio transmission (110 MHz-40 GHz) intended for use in wireless telecommunication networks with the basic restrictions or the reference levels related to general public exposure to radio frequency el
29、ectromagnetic fields, when put into service. 2 Rec. ITU-T K.61 (02/2008) IEC 60657 IEC 60657 (1979), Non-ionizing radiation hazards in the frequency range from 10 MHz to 300 000 MHz. IEC 61566 IEC 61566 (1997), Measurement of exposure to radio-frequency electromagnetic fields Field strength in the f
30、requency range 100 kHz to 1 GHz. IEC 62311 IEC 62311 (2007), Assessment of electronic and electrical equipment related to human exposure restrictions for electromagnetic fields (0 Hz - 300 GHz). ISO/IEC GUM ISO/IEC Guide 98:1995, Guide to the expression of uncertainty in measurement (GUM). 3 Terms a
31、nd definitions This Recommendation defines the following terms: 3.1 far-field region: That region of the field of an antenna where the angular field distribution is essentially independent of the distance from the antenna. In the far-field region, the field has predominantly plane-wave character, i.
32、e., locally uniform distribution of electric field strength and magnetic field strength in planes transverse to the direction of propagation. 3.2 near-field region: The near-field region exists in proximity to an antenna or other radiating structure in which the electric and magnetic fields do not h
33、ave a substantially plane-wave character but vary considerably from point to point. The near-field region is further subdivided into the reactive near-field region, which is closest to the radiating structure and that contains most or nearly all of the stored energy, and the radiating near-field reg
34、ion where the radiation field predominates over the reactive field, but lacks substantial plane-wave character and is complicated in structure. NOTE For many antennas, the outer boundary of the reactive near field is taken to exist at a distance of one wavelength from the antenna surface. 3.3 radio
35、frequency (RF): Any frequency at which electromagnetic radiation is useful for telecommunication. NOTE In this Recommendation, radio frequency refers to the frequency range 9 kHz-300 GHz allocated by ITU-R Radio Regulations. 3.4 specific absorption (SA): Specific absorption is the quotient of the in
36、cremental energy (dW) absorbed by (dissipated in) an incremental mass (dm) contained in a volume element (dV) of a given density (m). dVdWmdmdWSA=1The specific absorption is expressed in units of joules per kilogram (J/kg). 3.5 specific absorption rate (SAR): The time derivative of the incremental e
37、nergy (dW) absorbed by (dissipated in) an incremental mass (dm) contained in a volume element (dV) of a given mass density (m). =dVdWmdrddmdWdtdSAR1SAR is expressed in units of watts per kilogram (W/kg). Rec. ITU-T K.61 (02/2008) 3 SAR can be calculated by: mESAR=2dtdTcSAR = =mJSAR2where: E is the v
38、alue of the electric field strength in body tissue in V/m is the conductivity of body tissue in S/m m is the density of body tissue in kg/m3c is the heat capacity of body tissue in J/kgC dtdTis the time derivative of temperature in body tissue in C/s J is the value of the induced current density in
39、the body tissue in A/m23.6 wavelength (): The wavelength of an electromagnetic wave is related to frequency (f) and velocity (v) of an electromagnetic wave by the following expression: f= In free space, the velocity is equal to the speed of light (c) which is approximately 3 108m/s. 4 Abbreviations
40、and acronyms This Recommendation uses the following abbreviations and acronyms: AF Antenna Factor APC Automatic Power Control BCCH Base Station Control Channel CF Calibration Factor DTX Discontinuous Transmission EIRP Equivalent Isotropically Radiated Power EM Electromagnetic EMC Electromagnetic Com
41、patibility EMF Electromagnetic Field ICNIRP International Commission on Non-Ionizing Radiation Protection PC Personal Computer RF Radio Frequency RMS Root Mean Square SA Specific Absorption SAR Specific Absorption Rate 4 Rec. ITU-T K.61 (02/2008) UMTS Universal Mobile Telecommunication System 5 Gene
42、ral principles ITU-T K.52 provides a procedure for achieving a compliance with EMF safety limits. The steps needed to achieve compliance are: 1) Identify appropriate compliance limits. 2) Determine if EMF exposure assessment for the installation of equipment in question is needed. 3) If the EMF expo
43、sure assessment is needed, it may be performed by calculations or measurement. 4) If the EMF exposure assessment indicates that pertinent exposure limits may be exceeded in areas where people may be present, mitigation/avoidance measures should be applied. This Recommendation provides guidance on me
44、asurements and calculations of the EMF fields (step 3). Additional information on exposure assessment can be found in ITU-T K.70, ITU-R BS.1698, IEC 62311, EN 50383, EN 50400, b-IEC 62232, b-FprEN 50492, b-FprEN 50413 and b-IEEE P.1597.1. It is also recommended to ensure that exposure assessment is
45、conducted in accordance with the applicable national or regional standards and regulations. NOTE These more sophisticated methods to assess field exposure are needed to refine the zone boundaries obtained using ITU-T K.52 or for complex situations where the methods of ITU-T K.52 may be insufficient.
46、 For example, it may be useful to refine the results of ITU-T K.52 where they indicate an appearance of exceedance zone or occupational zone marginally. A measurement or more accurate calculation can help determine whether the zone determination is correct or is an artefact of the conservative estim
47、ation methods of ITU-T K.52. Another example where measurements may be needed is for complex scattering environments or for environments with a number of significant sources of EM radiation. 5.1 Quantities being measured Most documents provide safety limits in terms of basic restrictions and referen
48、ce (or derived) levels. The basic restrictions address the fundamental quantities that determine the physiological response of the human body to EMFs. Basic restrictions apply to a situation with the body present in the field. The basic restrictions for human exposure are expressed as the SAR, SA an
49、d current density. SAR assessment is not in the scope of this Recommendation. More information can be found in IEC 62311, EN 50383, b-IEC 62232, b-FprEN 50492, b-FprEN 50413 and b-IEEE P.1597.1. As the basic restrictions are difficult to measure directly, most documents provide derived reference levels for electric field, magnetic field and power density. The reference levels apply to a situation where the assessment of electromagnetic field is not influenced by the presence of a body. The n
