Emf measurement

1. PROJECT PROPOSAL
SYNOPSIS : Concern for the safety issues over health hazards due to radiations
emitting from Mobile Tower and Mobile phones, Government of India’s Department
of Telecom (DoT) decided to implement the new policy and regulation on
electromagnetic radiation emitted by Mobile Tower and Handsets from September
1,2012.The project deals with the measurement of the EMF(electromagnetic field )
radiation at public accessible sites around cellular base station and confirm
the compliance of base station installation as per the limits described by the
Department of Telecommunication.Study of the Emf exposure and its impact on
general public is one of the main aspect of this project.This project aims at
giving the basic idea of Emf radiation by telecom towers along with the approved
evaluation techniques.These evaluation techniques further cover all the three
methods,i.e, Calculation method, Field approach method as well as
electromagnetic mapping by Software simulation method the are employed in
assessment of EMF exposure.
The project is to ensure that a base station is EMF -complaint with respect to
current limits prescribed by Department of Telecommunication.However,ensuring a
base station further involves -Identification of non compliant
regions or zones;
-Implementing reasonable and practical engineering or administartive control
measures for identified non-compliance zones;
-Monitoring and documenting the control measures taken.
Basic installation classification scheme as well as categoziation of the EMF
exposure zones are a part of the project.This project ends with the submission
of the EMF compliance reports ,in format that depends upon the evaluation
technique used, to DoT and final audit by the TERM(Telecom Enforcement resource
and monitoring) cell of DoT.
GOALS: Measurement of the EMF(electromagnetic field ) radiation at public
accessible sites around cellular base station and confirm the compliance of
base station installation as per the limits described by the Department of
Telecommunication.
PROPOSED METHODOLOGY:The project begins with the EMF exposure assessment in the
presence of intentional emitters and is conducted for all locations where people
might be exposed to EMF in course of their normal activities.Exposure assessment
leads to the categorization of area surrounding the BTS into three categotries:
-Compliance zone;
-Occupational zone;
-Exceedance zone.
Installation classification Scheme sheds light on the three classes that a
emitter installation may belong to,depending upon its compliance,such as
-Inherently compliant;
-Normally compliant;
-Provisionally compliant.
further, any of the three or all three evaluation techniques are employed for
the Compliance of the emf exposure levels.These evaluation techniques are as
follows:
a) Calculation method : Under this,following two methds are prescribed out of
which any one could be used for predicting compliance to radiation limits
-Prediction of RF field
-Calculation method for determination of
EIRPth
b) Field measurement Approach
c) Electromagnetic mapping by Software Simulation Method
Initially, EIRP(equivalent isotropically radiated power) of the antenna
system(BTS)-averaged radiated power of the antenna at a particular frequency ,is
measured for mean transmitted power.
If this value is less than 2W,the emitter installation is said to be inherently
compliant and does not require any further assessment.Inherently compliant
sources produce fields that comply with relevant exposure limits few centimeters

2. away from source and hence,do not require any precautions.
While on the other case,i.e,EIPR >2w, exposure measurement procedure is taken to
determine the approprtiate EMF Limits at a particular frequency as well as
EIRPth(for given accessibility and directivity).EIRPth is threshold value of
EIRP that corressponds to the exposure limit for power density or field from the
reference antenna for the accessibility condition.This is done by any of the
evaluation methods,i.e,calculations or measurement.If EIRP<EIRPth, then the
installation is said to be normally compliant and requires no further protection
methods.Normally compliant installations contain sources that produce EMF that
can exceed relevant exposure limits but this exceedence zone is not accessible
to people under ordinary circumstances.However if EIRP>EIRPth, the installation
is said to be provisionally compliant
which requires special measures to achieve compliance.Exposure zones are
determined using analytical,numerical and field measurement methods.mitigation
techniques are used if exposure zones are accessiblle,otherwise no further
precautions are taken.
Self certification by Service operator:
SCHEDULE :a) Calculationof EIRP/EIRPth : Assessment of the value of EIRP/EIRPth
is made at publicly accessible points in the environment surrounding the BTS
site.If its value is less than 1 at all the points outside the exclusion
zone,the site is taken as compliant.
b) Electromagnetic Mapping by Software Simulation :
electronic mapping can be based on any of the methods mentioned in the ITU -T
recommendation K-70/61,which include the following:-
Ray tracing model,as per ITU-T rec. K.61
-Point Source model, as per ITU-T rec.K.70
test result of software simulation are in the form of
power density in percentage of the refernce levels prescribed for general public
for various positions 2 m above roof top level of BTS
site, ground level, and Roof top of adjacent buildings in the vicinity of 60m
from BTS under consideration.
If electromagnetic mapping by software simulation are
within the 50 percent of the limits prescribed by the DoT,site can be self
certified as compliant.
c) Broadband Measurements-Broadband measurements that give
overall value of the Electric field or power density are done for the first
stage audit verification by TERM cell to certify EMF
compliance of BTS subject to the condition that measured value do not exceed 50%
of the power density limits prescribed by DoT for
general public.broadband measurements are taken with the help of an isotropic
field probe.the exceedance of levels beyond 50% of the
power density limits under broadband measurement doesnt amount to site being
non-compliant.In this condition ,frequency selective
measurement should be conducted .
d) Frequency Selective measurements - frequency selective
measurements with extrapolation for maximum traffic must be performed if
broadband measurement exceeds 50% of the limits
prescribed by DoT.High sensitivity,frequency selective measuring instrument can
be used to detect the source responsible for overall non
compliance.
e)report completion
f)Submission of report to DoT
REFERENCES:Following ITU -T recommendations:
-ITU-T Recommendation K.52(2004),Guidance on complying
with limits for human exposure to electromagnetic fields.
-ITU-T Recommendation K.61(2003),Guidance to measurement
and numerical predictions of electromagnetc fields for compliance with human
exposure limits for telecommuniation installations
-ICINRP Guidance for limiting exposure to time varying
Electric ,magnetic and electromagnetic fields (upto 300 GHZ)