1、IEEE Standards InterpretationsforIEEE Std C95.1 -2005IEEE Standard for Safety Levels with Respectto Human Exposure to Radio FrequencyElectromagnetic Fields, 3 kHz to 300 GHzCopyright 2009 by the Institute of Electrical and Electronics Engineers, Inc.Three Park AvenueNew York, New York 10016-5997 USA
2、All Rights Reserved.This is an interpretation of IEEE Std C95.1-2005. Interpretations are issued to explain and clarify the intent of astandard and are not intended to constitute an alteration to the original standard or to supply consultinginformation. Permission is hereby granted to download and p
3、rint one copy of this document. Individuals seekingpermission to reproduce and/or distribute this document in its entirety or portions of this document must contactthe IEEE Standards Department for the appropriate license. Use of the information contained in this document isat your own risk.IEEE Sta
4、ndards DepartmentCopyrights and Permissions445 Hoes Lane, P. O. Box 1331Piscataway, New Jersey 08855-1331, USANovember 2009Interpretation Request #1Please clarify the following portions of this standard:1. On page 28 of IEEE Std C95.1-2005, 4.6, it states “Relaxation of the power density MPE for loc
5、alisedexposures.“ We are not sure if this standard is applicable if the RF radiating devices is 0.1m from the humanbody. Can this standard be applied, using the relaxation of power density MPE?2. On page 29 of IEEE Std C95. last paragraph of 4.7, it states that “A practical guideline for eliminating
6、 theneed to assess whether the whole body average SAR exceeds the basic restriction of 0.4W/kg (or 0.08 W/kg) isto determine if the power of the sources(s) exceeds 28W (upper tier) or 5.6W (lower tier) for an average man(70kg).“ It is not clear how to interpret this statement. If each individual RF
7、source passes their full body SAR,can their individual measured SAR be totaled and ensure that they do not exceed 0.4W/kg or 28W (based on11/13/2009 IEEE Std C95.1-2005standards.ieee.org/C95.1-2005.html 1/370kg for average person)?Interpretation Response #1An interpretation of IEEE Std C95.1-2005 ha
8、s been requested regarding:1. Relaxation of the power density maximum permissible exposure (MPE) for localized exposures(4.6).2. The assessment of the basic restriction based upon the power of the sources (4.7).Subclause 4.6 (relaxation of the power density MPEs for localized exposures) states, in p
9、art, “Compliance withthe MPE of Table 8 (upper tier) is determined from spatial averages of power density or the mean squaredelectric and magnetic field strengths over an area equivalent to the vertical cross section of the human body(projected area) at a distance no closer than 0.2 meters from the
10、field source.” Because of measurementuncertainty, relaxation of the power density MPEs for localized exposures at distances closer than 0.2 metersfrom the source is not permitted. That is, the provisions of 4.6 (relaxation of power density MPE values) do notapply for exposures determined by field me
11、asurements made within 0.2 meters of a source.Additional reasons for the recommendation against relaxation of MPEs for localized exposures within the 0.2meter exclusion distance specified in 4.6 include the following: RF burns are possible when accidentally contacting RF sources and these probably c
12、onstitute themost harmful RF exposure hazard (C.1.2.1 Risk profile for adverse effects). Near sufficiently high powered RF sources there can be localized RF heating effects that areundeniably realistic hazards, but occur much less commonly than RF burns (C1.2.2 Risk profile foradverse effects).There
13、fore, relaxation of the power density MPE for localized human RF exposures within 0.2 m from a source isnot permitted by 4.6 of IEEE Std C95.1-2005.Regarding the source power levels discussed in 4.7 (assessing compliance with this standard) that are used fordetermining SAR, the governing portion of
14、4.7 states: “A practical guideline for eliminating the need to assesswhether the whole-body average SAR exceeds the basic restriction of 0.4 W/kg (or 0.08 W/kg when the lowertier is used as an exposure limit for the public) is to determine if the power of the source(s) exceeds 28 W (uppertier) or 5.
15、6 W (lower tier) for an average man (70kg).”Therefore, if the sum of the power of the sources is less than 28 W for the upper tier or 5.6 W for the lower tier,then the need to assess whether the whole-body average SAR exceeds the basic restriction is eliminated. Bear inmind that the last sentence of
16、 4.7 states: “Such a determination, however, does not necessarily imply that thebasic restriction on local SAR would not be exceeded.”11/13/2009 IEEE Std C95.1-2005standards.ieee.org/C95.1-2005.html 2/3In summary:1. The provisions of 4.6 of IEEE Std C95.1-2005 do not permit relaxation of the power d
17、ensityMPEs for localized exposures at distances closer than 0.2 meters from a source.2. If the sum of the power of the sources is less than 28 W for the upper tier or 5.6 W for the lowertier, then the need to assess whether the whole-body average SAR exceeds the basic restriction iseliminated, accor
18、ding to 4.7 of IEEE Std C95.1-2005. Such a determination does not imply thatthe basic restriction on local SAR would not be exceeded.Back to Available IEEE Standards Interpretations Online Copyright IEEE-SA Contac t IEEE-S A For questions or comments, please contact the IEEE-SA Webmaster.11/13/2009 IEEE Std C95.1-2005standards.ieee.org/C95.1-2005.html 3/3
