1、 International Telecommunication Union ITU-T K.91TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2012) SERIES K: PROTECTION AGAINST INTERFERENCE Guidance for assessment, evaluation and monitoring of human exposure to radio frequency electromagnetic fields Recommendation ITU-T K.91 Rec. ITU-T K.9
2、1 (05/2012) i Recommendation ITU-T K.91 Guidance for assessment, evaluation and monitoring of human exposure to radio frequency electromagnetic fields Summary There are many possible methods of exposure assessment and each of them has its own advantages and disadvantages. Recommendation ITU-T K.91 g
3、ives guidance on how to assess and monitor human exposure to radio frequency (RF) electromagnetic fields (EMF) in areas with surrounding radiocommunication installations based on existing exposure and compliance standards in the frequency range of 9 kHz to 300 GHz. This includes procedures of evalua
4、ting exposure and how to show compliance with exposure limits with reference to existing standards. Recommendation ITU-T K.91 is oriented to the examination of the area accessible to people in the real environment of currently operated services with many different sources of RF EMF, but also gives r
5、eferences to standards and Recommendations related to EMF compliance of products. This Recommendation includes an electronic attachment containing an uncertainty calculator and the Watt Guard modules. History Edition Recommendation Approval Study Group 1.0 ITU-T K.91 2012-05-29 5 ii Rec. ITU-T K.91
6、(05/2012) FOREWORD The International Telecommunication Union (ITU) is the United 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 responsibl
7、e for studying technical, operating and tariff questions and issuing Recommendations 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
8、study groups which, in turn, produce Recommendations on these topics. The approval 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 ba
9、sis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ 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 mandator
10、y provisions (to ensure, e.g., interoperability or applicability) and compliance with 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 u
11、se of such words does not suggest that compliance with the Recommendation is required 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 n
12、o position concerning the evidence, validity or applicability of claimed Intellectual 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,
13、 protected by patents, which may be required to implement this Recommendation. However, 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 2013 All rights reserved. No
14、part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T K.91 (05/2012) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 7 4 Abbreviations
15、and acronyms 7 5 General guidance 8 5.1 General public and occupational exposure . 10 5.2 Existing or planned transmitting station . 10 5.3 Collection of data concerning the sources of radiation 10 5.4 One or more sources of radiation, total exposure . 12 5.5 Field regions . 13 5.6 Basic restriction
16、s and reference levels . 13 5.7 Exposure limits . 13 5.8 Compliance assessment 14 5.9 Uncertainty evaluation 14 5.10 Exposure assessment in areas around hospitals, schools, etc. 15 6 General characteristics of typical sources of the radiation . 15 6.1 AM transmitting stations 16 6.2 SW transmitting
17、station main beam tilt . 16 6.3 Fixed amateur stations 16 6.4 Fixed point-to-point systems 16 6.5 Handsets isotropic sources 17 6.6 VHF and UHF broadcasting transmitting stations . 21 6.7 2G and 3G mobile base stations . 21 6.8 Smart (adaptive) antennas 22 6.9 Vehicle mounted antennas (such as polic
18、e car) 22 7 Exposure assessment 22 7.1 Pre-analysis . 22 7.2 Measurements . 22 7.3 Calculations 29 7.4 Comparison between measurement and calculations . 34 7.5 Monitoring RF EMF levels 36 8 Conclusions following the exposure assessment 36 9 Final report . 36 10 Field levels around typical transmitti
19、ng antennas 37 11 Conclusions 37 iv Rec. ITU-T K.91 (05/2012) Page Appendix I Exposure limits 38 I.1 Introduction 38 I.2 Exposure limits . 38 I.3 ICNIRP exposure limits . 38 I.4 Simultaneous exposure to multiple sources . 40 I.5 IEEE International Committee Electromagnetic Safety (ICES) exposure lim
20、its . 41 Appendix II Time averaging . 43 II.1 Analysis of time variations of measured electric fields from WCDMA mobile base stations 43 II.2 Analysis of time variations of measured electric fields from GSM mobile base stations 48 II.3 Results and discussion 49 II.4 Discussion about the number of sa
21、mpling data and averaging time 51 Appendix III Examples of RF EMF levels in areas accessible to the general public . 53 Appendix IV Software Watt Guard 57 Appendix V Software “Uncertainty calculator“ 58 V.1 Introduction 58 V.2 Brief descriptions of the software . 58 V.3 Examples 60 Appendix VI Examp
22、les for evaluating electromagnetic fields in general public environments with broadband radio signals . 64 VI.1 Method for evaluating electromagnetic fields in general public environments with broadband signals 64 VI.2 Effect of RBWs on measured electromagnetic fields from mobile phone base stations
23、 65 Appendix VII Example of block diagram with possible activities during exposure assessment 68 Bibliography. 69 Electronic attachment: Uncertainty calculator and Watt Guard Rec. ITU-T K.91 (05/2012) 1 Recommendation ITU-T K.91 Guidance for assessment, evaluation and monitoring of human exposure to
24、 radio frequency electromagnetic fields 1 Scope This Recommendation1gives guidance on how to assess and monitor human exposure to radio frequency (RF) electromagnetic fields (EMF) in areas with surrounding radiocommunication installations based on existing exposure and compliance standards in the fr
25、equency range of 9 kHz to 300 GHz. This Recommendation presents and references in clear and simple ways, procedures of evaluating exposure and how to show compliance with exposure limits. Existing standards are product or service oriented. This Recommendation is oriented to the examination of the ar
26、ea accessible to people in the real environment of currently operated services with many different sources of RF EMF, but also gives references to standards and Recommendations related to EMF compliance of products. 2 References The following ITU-T Recommendations and other references contain provis
27、ions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibil
28、ity of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommenda
29、tion. ITU-T K.52 Recommendation ITU-T K.52 (2004), Guidance on complying with limits for human exposure to electromagnetic fields. ITU-T K.61 Recommendation ITU-T K.61 (2003), Guidance to measurement and numerical prediction of electromagnetic fields for compliance with human exposure limits for tel
30、ecommunication installations. ITU-T K.70 Recommendation ITU-T K.70 (2007), Mitigation techniques to limit human exposure to EMFs in the vicinity of radiocommunication stations. ITU-T K.83 Recommendation ITU-T K.83 (2010), Monitoring of electromagnetic field levels. ITU-R BS.1195 Recommendation ITU-R
31、 BS.1195 (1995), Transmitting antenna characteristics at VHF and UHF. ITU-R BS.1698 Recommendation ITU-R BS.1698 (2004), Evaluating fields from terrestrial broadcasting transmitting systems operating in any frequency band for assessing exposure to non-ionizing radiation. ICNIRP ICNIRP (1998), ICNIRP
32、 Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic and Electromagnetic Fields (up to 300 GHz), Health Physics, Vol. 74, No. 4; pp. 494-522. http:/www.icnirp.de/documents/emfgdl.pdf _ 1This Recommendation contains an electronic attachment containing an uncertainty calculator and the
33、 Watt Guard applications. 2 Rec. ITU-T K.91 (05/2012) IEC 62209-1 IEC 62209-1 (2005), Human exposure to radio frequency fields from hand-held and body-mounted wireless communication devices Human models, instrumentation, and procedures Part 1: Procedure to determine the specific absorption rate (SAR
34、) for hand-held devices used in close proximity to the ear (frequency range of 300 MHz to 3 GHz). http:/webstore.iec.ch/webstore/webstore.nsf/ArtNum_PK/33746?OpenDocument IEC 62209-2 IEC 62209-2 (2010), Human exposure to radio frequency fields from hand-held and body-mounted wireless communication d
35、evices Human models, instrumentation, and procedures Part 2: Procedure to determine the specific absorption rate (SAR) for wireless communication devices used in close proximity to the human body (frequency range of 30 MHz to 6 GHz). http:/webstore.iec.ch/webstore/webstore.nsf/ArtNum_PK/43905?OpenDo
36、cument IEC 62232 IEC 62232 (2011), Determination of RF field strength and SAR in the vicinity of radiocommunication base stations for the purpose of evaluating human exposure. http:/webstore.iec.ch/webstore/webstore.nsf/ArtNum_PK/45152?OpenDocument IEEE C95.1 IEEE C95.1-2005, Standard for Safety Lev
37、els with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz. http:/ieeexplore.ieee.org/xpl/articleDetails.jsp?tp= workers are more likely to approach closer to the RF sources (transmitting antennas) so in more cases the area under examination is located in the reac
38、tive near-field region, which, as a consequence, requires more sophisticated methods for the exposure assessment by measurement or by calculation; workers in some cases are allowed to stay in areas with exposure levels above the limits but for limited time periods or by using mitigation measures lik
39、e protective clothes. 5.2 Existing or planned transmitting station If the area under consideration is covered by emissions from existing RF sources only, then the exposure assessment can be performed either by measurements or by calculations. If in the area under consideration some new RF EMF source
40、s are planned (even if there exist other operating radio systems), the possibility to check compliance is through the exposure assessment by calculation or by a combination of measurement and calculation. 5.3 Collection of data concerning the sources of radiation Collection of data concerning the RF
41、 sources is helpful in many respects. If exposure assessment by measurement is planned, it is in principle possible to do without these data, but measurements without data concerning the RF sources are more difficult and results of measurements are less reliable. Data collection is required for expo
42、sure assessment by calculation. Generally, more detailed descriptions of the RF sources are available more exact results of evaluation can be obtained. This Recommendation considers intentional radiation from transmitting antennas. So the description of these antennas is most important. It should be
43、 noted that much of the detailed information may be commercially sensitive and may be difficult to collect. 5.3.1 Data required for the measurement In general, measurements can be done without complete knowledge of the radiating sources if proper equipment that covers the full range of frequencies i
44、s available, knowing at least the range of frequencies to be measured. If measurements are made with wideband equipment (without frequency selection or shaped response), the results of such measurement will be conservative because it requires the use of the limit value, which is most restrictive. In
45、 all cases of measurements, the information concerning the radiating sources is very helpful and makes the measurements more accurate and reliable. Rec. ITU-T K.91 (05/2012) 11 The following data are very helpful during measurements (for each radiating source): operating frequency this allows use of
46、 a probe that has a band covering all operating frequencies; distance to the transmitting antenna this allows one to determine the field region (for each operating frequency) and to choose a proper measurement procedure; maximum ERP this allows estimation of the required dynamic range of the measure
47、ment equipment and the expected levels of the measured values; whether the antennas are operating at the maximum transmitter power at the time of the measurements; modulation characteristics especially pulsed, intermittent or continuous operation. Usually this information can be obtained from the do
48、cumentation of the transmitting systems. Some data can be obtained during the site inspection (distances to the transmitting antennas, operating frequencies based on the types and sizes of the transmitting antennas, etc.). 5.3.2 Data required for the calculations Exposure assessment by calculation i
49、n all cases requires information concerning radiating sources. In general, the more detailed the information, the more accurate are the results of calculations. These data are required for each operating (or planned) frequency. The required data put in order of growing level of accuracy of the exposure assessment by calculation are presented below. The minimum data required for calculation, which leads to the most conservative approach, are: operating frequen
