RE: Demonstrating compliance with Human Exposure to EMF requireme nts
Charlie I passed your question to a collegue of mine at ERA, Dr Parvinder Bansal, who specialises in this area as well as in antenna modelling, EMF exposure advice and EMF site surveys. You will see below that I am passing on his comments as he is not on EMC-PSTC, and he may be able to assist you further if you contact him directly: John Allen, Technical Consultant Safety Risk Management ERA Technology Ltd. Cleeve Road Leatherhead Surrey KT22 7SA UK Tel: +44-1372-367025 (Direct) +44-1372-367000 (Switchboard) Fax: +44-1372-367102 Parvinder's comments:- Dear Charlie, The Council Recommendation of 12th July 1999 on Limitation of Exposure of the General Public to Electromagnetic Fields (0Hz to 300GHz) as it states is for safeguarding the general public from EMFs. This recommendation refers to the ICNIRP reference levels for exposure to the general public to a level of 61V/m which should not be exceeded. However, the ICNIRP guidelines are not limits but levels to which a comparison should be made. If the levels have been exceeded then further investigations are required to ensure that the basic restrictions are not exceeded. It would be highly unlikely that members of the general public would frequent areas on rooftops for long periods of time and particularly in the boresight of the antenna! Antenna installers and maintenance engineers might get close to the antenna to carry out work, and the ICNIRP reference level for workers is 137V/m. Although, the site would be clearly marked off around the antenna to show hazardous regions from EMFs around the antenna, and would be clearly sign posted with the appropriate danger sign. In your case an electric field strength of 10V/m at 0.5m was calculated for your antenna. This is permissible, but may also wish to add for this antenna to operate as intended, any opaque objects which might act as reflectors (metallic walls, structures, vehicles, etc.) or scatters (building walls and human beings) must be at least x(metres) from the radiating part of the antenna for high quality reception and transmission. This would be clearly stated in the Technical Construction File (TCF) or on the documents that shows compliance with the relevant European Standards on EMC radiated emission and immunity for your antenna. The main concern that the Council Recommendation refer to is inadvertent exposure to the general public and in most cases is exposure of the general public from side-lobes of the antenna's radiation pattern. Parvinder S Bansal Principal Engineer/Consultant EM, Safety Reliability Tele : 01372 367278 Fax : 01372 367102 e-mail to : parvinder.ban...@era.co.uk From: Charles Blackham [mailto:cblac...@airspan.com] Sent: 26 March 2003 16:49 To: emc-pstc Subject: Demonstrating compliance with Human Exposure to EMF requirements All I'm attempting to demonstrate the compliance of our fixed wireless access system with the human exposure to EMF requirements of Article 3.1a of the RTTE directive: The applicable standard, EN50385, requires the field strengths to be measured/calculated according to EN50383 against the limits detailed in 1999/519/EC. My reading of 1999/519/EC is that the maximum allow E-filed is 61 V/m for 2-300 GHz. I calculate that our subscriber equipment is generating a field of 10 V/m at 0.5m distance. So, so save measuring/calculating near field values, can I just add to the user manual that you should not stand within 0.5m of the front of the equipment? (The antenna wouldn't work so well if you did, and it would be difficult to anyway as it typically pole/chimney mounted) regards Charlie Blackham Approvals Manager Airspan Communications This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc _ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com * Copyright ERA Technology Ltd. 2003. (www.era.co.uk). All rights reserved. The information supplied in this Commercial Communication should be treated in confidence. No liability whatsoever is accepted for any loss or damage suffered as a result of
RE: Demonstrating compliance with Human Exposure to EMF requireme nts
Charlie, 1/2 lambda is 7.5 cm at 2 GHz. At this distance the field strength is 67 V/m assuming far field. So, no near field calculations are needed as long as the distance is greater than approximately 10 cm. The actual field is not that difficult to calculate anyway. Or, just use NEC to simulate the field strength. Dave Cuthbert Micron Technology From: Charles Blackham [mailto:cblac...@airspan.com] Sent: Wednesday, March 26, 2003 9:49 AM To: emc-pstc Subject: Demonstrating compliance with Human Exposure to EMF requirements All I'm attempting to demonstrate the compliance of our fixed wireless access system with the human exposure to EMF requirements of Article 3.1a of the RTTE directive: The applicable standard, EN50385, requires the field strengths to be measured/calculated according to EN50383 against the limits detailed in 1999/519/EC. My reading of 1999/519/EC is that the maximum allow E-filed is 61 V/m for 2-300 GHz. I calculate that our subscriber equipment is generating a field of 10 V/m at 0.5m distance. So, so save measuring/calculating near field values, can I just add to the user manual that you should not stand within 0.5m of the front of the equipment? (The antenna wouldn't work so well if you did, and it would be difficult to anyway as it typically pole/chimney mounted) regards Charlie Blackham Approvals Manager Airspan Communications This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Demonstrating compliance with Human Exposure to EMF requireme nts
If you are going to claim compliance to EN50385, you will have to make the assessment according to the standard. Otherwise, you have the following choices: Claim safety conformity to the procedures of the RTTE Directive and create a Technical Construction File and consult with a Notified Body as to the assessment method. Claim safety conformity to the procedures of the LVD (the RTTE Directive allows this)and build a TCF. Under the LVD the use of a Notified Body is not required if harmonized standards are not applied. Obviously, this process has risks since a harmonized standard does exist. In case of challenge, conformity may be difficult to prove without the opinion of a NB. However, I did use this route myself when the the EMF standard I use was in draft form. In your case you should probably use one of the first two choices. Richard Woods Sensormatic Electronics Tyco International From: Charles Blackham [mailto:cblac...@airspan.com] Sent: Wednesday, March 26, 2003 11:49 AM To: emc-pstc Subject: Demonstrating compliance with Human Exposure to EMF requirements All I'm attempting to demonstrate the compliance of our fixed wireless access system with the human exposure to EMF requirements of Article 3.1a of the RTTE directive: The applicable standard, EN50385, requires the field strengths to be measured/calculated according to EN50383 against the limits detailed in 1999/519/EC. My reading of 1999/519/EC is that the maximum allow E-filed is 61 V/m for 2-300 GHz. I calculate that our subscriber equipment is generating a field of 10 V/m at 0.5m distance. So, so save measuring/calculating near field values, can I just add to the user manual that you should not stand within 0.5m of the front of the equipment? (The antenna wouldn't work so well if you did, and it would be difficult to anyway as it typically pole/chimney mounted) regards Charlie Blackham Approvals Manager Airspan Communications This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
