47 Figures Figure 1 Alternative routes to determine the total exposure ratio where the general public has access ...12 Figure 2 Overview of the general method to estimate the total e
Quantities
The internationally accepted SI-units are used throughout the standard.
Electric field strength E volt per meter V/m
Electric flux density D coulomb per square meter C/m2
Magnetic field strength H ampere per meter A/m
Magnetic flux density B tesla (Vs /m2) T
Mass density ρ kilogram per cubic meter kg/m3
Specific absorption rate SAR watt per kilogram W/kg
This basic standard applies to Base Stations as defined in Clause 4, operating in the frequency range 110 MHz to 40 GHz.
This standard aims to define the methods for evaluating the Total Exposure Ratio of equipment when it is deployed in its operational environment, ensuring that this ratio is less than or equal to one in areas accessible to the general public.
The referenced documents are essential for the application of this document For dated references, only the specified edition is applicable, while for undated references, the most recent edition, including any amendments, is relevant.
Council Recommendation 1999/519/EC of 12 July 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz)
EN 50383 is the fundamental standard for assessing and measuring electromagnetic field strength and Specific Absorption Rate (SAR) concerning human exposure from radio base stations and fixed terminal stations used in wireless telecommunication systems operating within the frequency range of 110 MHz to 40 GHz.
EN ISO/IEC 17025:2000, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:1999)
ISO Guide to the expression of uncertainty in measurement: Ed.1 1995
International Commission on Non-Ionizing Radiation Protection (1998), Guidelines for limiting exposure in time-varying electric, magnetic, and electromagnetic fields (up to 300 GHz)
3 Physical quantities, units and constants
The internationally accepted SI-units are used throughout the standard.
Electric field strength E volt per meter V/m
Electric flux density D coulomb per square meter C/m2
Magnetic field strength H ampere per meter A/m
Magnetic flux density B tesla (Vs /m2) T
Mass density ρ kilogram per cubic meter kg/m3
Specific absorption rate SAR watt per kilogram W/kg
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)
Constants
Speed of light in a vacuum c 2,997 x 108 m/s
Impedance of free space η 0 120 π Ω (approx 377Ω)
For the purposes of this document, the following terms and definitions apply.
An antenna device functions as a transducer, converting guided waves, such as those from coaxial cables, into free space waves, and vice versa It is capable of both emitting and receiving radio signals In the current standard, the term "antenna" specifically refers to emitting antennas unless stated otherwise.
4.2 average emitted power the average emitted power is the time-averaged rate of energy transfer defined by
P t where t 2 t 1 is the averaging time, t avg defined as a function of frequency in the Council Recommendation
P(t) is the power radiated by the antenna at the maximum duty cycle of the equipment
4.3 average equivalent isotropic radiated power (average EIRP) the product of the power supplied to the antenna and the maximum antenna gain relative to an isotropic antenna
P aep is the average emitted power;
G is the maximum gain of the antenna relative to an isotropic antenna
Base stations (BS) are essential fixed equipment for radio transmission in cellular communication and wireless local area networks This includes both point-to-point and point-to-multipoint communication equipment According to this standard, a base station encompasses the radio transmitter(s) and their associated antenna(s).
Basic restrictions on exposure to time-varying electric, magnetic, and electromagnetic fields are grounded in established health effects These restrictions vary based on the frequency of the field and are quantified using current density (J), specific absorption rate (SAR), and power density (S).
4.6 compliance boundary (CB) the compliance boundary is defined according to EN 50383
4.7 domain of investigation (DI) sub-domain of relevant domain where the general public may have access when the base station is put into service
4.8 electric field strength ( E ) the magnitude of a field vector at a point that represents the force (F) on a small test charge (q) divided by the charge
Electric field strength is expressed in units of volt per meter (V/m)
4.9 equipment under test (EUT) base station that is the subject of the specific test investigation being described
4.10 equivalent free space conditions (EFSC) conditions allowing re-use of free space methods defined in EN 50383
The power density of a plane wave in free space, measured per unit area and perpendicular to its direction of propagation, is connected to the electric and magnetic fields through a specific mathematical expression.
4.12 exposure ratio (ER) the assessed exposure parameter at a specified location for each operating frequency of a radio source, expressed as the fraction of the related limit
For assessment against the basic restrictions
For assessments against reference levels:
ER or between 10 MHz and 40 GHz:
ER is the exposure ratio at each operating frequency for the source;
EL is the investigation E-field limit at frequency f;
HL is the investigation H-field limit at frequency f;
SARWBL is the SAR whole body limit at frequency f;
SARPBL is the SAR partial body limit at frequency f;
SL is the equivalent plane wave power density limit at frequency f;
E is the assessed E-field at frequency f for the source;
H is the assessed H-field at frequency f for the source;
SARwb is the assessed whole body SAR at frequency f for the source (EN 50383);
SARpb is the assessed partial body SAR at frequency f for the source (EN 50383);
S is the assessed equivalent plane wave power density at frequency f for the source; f is each operating frequency of the source
ER is applicable to limits based on ICNIRP principles
The intrinsic impedance of free space, denoted as η₀, is defined as the ratio of the electric field strength to the magnetic field strength in a propagating electromagnetic wave For a plane wave traveling through free space, this intrinsic impedance is approximately 377Ω, which can also be expressed as \(120\pi\) Ω.
Isotropy is a physical property that remains constant regardless of direction Axial isotropy refers to the maximum variation in a measured quantity when a probe is rotated along its main axis while exposed to a reference wave at normal incidence In contrast, hemispherical isotropy is defined by the maximum deviation in the measured quantity when the probe is rotated along its main axis while exposed to a reference wave with varying angles of incidence and polarization in the half space in front of the probe.
4.15 linearity the maximum deviation over the measurement range of the measured quantity value from the closest linear reference curve defined over a given interval
4.16 magnetic field strength (H) the magnitude of a field vector in a point that results in a force ( F ) on a charge q moving with the velocity v
The magnetic field strength is expressed in units of amperes per meter (A/m)
4.17 magnetic flux density (B) the magnitude of a field vector that is equal to the magnetic field strength H multiplied by the permeability (à) of the medium
Magnetic flux density is expressed in units of tesla (T)
4.18 permeability ( à ) the magnetic permeability of a material is defined by the magnetic flux density B divided by the magnetic field strength H: à = B
H where àis the permeability of the medium expressed in henry per metre (H/m)
4.19 permittivity ( ε ) the property of a dielectric material (e.g., biological tissue) In case of an isotropic material, it is defined by the electrical flux density D divided by the electrical field strength E ε = D
The permittivity is expressed in units of farad per metre (F/m)
The point of investigation (PI) refers to the specific location within the investigation domain where the values of the electric field (E-field), magnetic field (H-field), or power density are assessed This location is determined using Cartesian, cylindrical, or spherical coordinates in relation to a reference point on the Equipment Under Test, as outlined in EN 50383.
4.21 power density (S) the radiant power incident perpendicular to a surface, divided by the area of the surface The power density is expressed in units of watt per square metre (W/m 2 )
Reference levels are established to facilitate the comparison of exposure quantities in the air Adhering to these reference levels is essential to ensure compliance with the basic restrictions This applies specifically within the frequency range of 110 MHz.
40 GHz the reference levels are expressed as electric field strength, magnetic field strength and power density values
The reference point for antennas is determined by the center of the rear reflector for panel antennas and by the center of the antenna for omni-directional antennas For other configurations, it is essential to establish suitable reference points.
4.25 relevant domain (RD) domain surrounding the antenna where the equipment under test may be considered as a relevant source
4.26 relevant source (RS) a radio source, in the frequency range 100 kHz to 40 GHz, which at a given point of investigation has an exposure ratio larger than 0,05
4.27 specific absorption rate (SAR) the time derivative of the incremental energy (dW) absorbed by (dissipated in) an incremental mass (dm) contained in a volume element (dV) of given mass density (ρ )
SAR is expressed in units of watt per kilogram (W/kg)
NOTE SAR can be calculated by
E i is r.m.s value of the electric field strength in the tissue in V/m; σ is conductivity of body tissue in S/m; ρ is density of body tissue in kg/m3
The scatter domain (SD) surrounding the antenna can significantly alter the compliance boundary estimated in free space, as outlined by EN 50383 This domain is influenced by structures that may cause reflected or diffracted fields, particularly extensive surfaces such as walls, while excluding elements like railings and ladders.
The Total Exposure Ratio (TER) is defined as the maximum value of the sum of exposure ratios from the Equipment Under Test and all relevant sources, measured across a frequency range of 100 kHz to 40 GHz.
EREUT is the assessed Exposure Ratio from the Equipment Under Test;
ERRS is the assessed Exposure Ratio of all the Relevant Sources
4.30 transmitter device to generate radio frequency electrical power to be connected to an antenna for communication purpose
Alternative routes to determine the total exposure ratio where the general public
This standard outlines the methods for determining or overestimating the total exposure ratio in areas accessible to the general public, specifically within the investigation domain Various alternative routes, as illustrated in Figure 1, can be utilized, and any completed route is considered valid for this assessment.
Choose either, the general method described in 5.2, or the pre-analysis method according to 5.3.
The TER is 1 in DI
Figure 1 Alternative routes to determine the total exposure ratio where the general public has access
For sources with time-varying power, the value of the average emitted power at the maximum power setting of the equipment shall be used.
General method
Description of the general method
The total exposure ratio shall be determined following the process in the flow chart in Figure 2.
5.1 Alternative routes to determine the total exposure ratio where the general public has access
This standard outlines the methods for determining or overestimating the total exposure ratio in areas accessible to the general public It emphasizes the importance of assessing various alternative routes, as illustrated in Figure 1, with any completed route being considered valid for this evaluation.
Choose either, the general method described in 5.2, or the pre-analysis method according to 5.3.
The TER is 1 in DI
Figure 1 Alternative routes to determine the total exposure ratio where the general public has access
For sources with time-varying power, the value of the average emitted power at the maximum power setting of the equipment shall be used
5.2 General method 5.2.1 Description of the general method
The total exposure ratio shall be determined following the process in the flow chart in Figure 2.
ISO “Guide to the expression of uncertainty in measurement”, Ed.1 1995 by
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)
The TER is 1 in DI
Site certificate, building permit or operation approval (clause 5.4) No
After 5.3, add the following new subclause:
In countries like Germany, Italy, and Switzerland, the standards for site certification, building permits, and operation approvals are integrated into regulatory procedures that must be adhered to.
NOTE As examples, the regulatory procedures in Germany, Italy and Switzerland are described in Annexes F, G and H
Add the following new Annexes F, G and H:
Does general public have access to the volume defined by the EUT CB?
Step 1 - Determine the CB of the EUT
Step 2 - Determine the RD & DI of the EUT (clause 6)
Does the DI exist in RD?
Step 3 - Determine the SD of the EUT (clause 6) Determine the RS (clause 6)
Is there a reflecting structure in SD?
The TER may be > 1 in DI
The TER is 3 GHz
Steps Max (λ, d/40) Max (2 m, d/40) 1 m 0,5 m d is the distance (m) from the point of investigation to Relevant Source Annex D.
Border of a restricted area located in the domain of investigation (DI)
The methods for calculating and measuring electromagnetic fields are influenced by the location of the investigation point in relation to the source antenna, which can be categorized into reactive near-field, radiating near-field, or far-field regions (EN 50383) In the radiating near-field and far-field, it is possible to estimate the electric field (E-field), magnetic field (H-field), or power density through calculations and measurements Conversely, in the reactive near-field, it is advisable to conduct specific absorption rate measurements in accordance with EN 50383.
The assessed total exposure ratio at each investigation point will be the highest value obtained from measurements taken at three different heights above a public walkway (see Figure 4).
Figure 4 Location of the three assessments for each point of investigation
Pre-analysis method
The pre-analysis method establishes guidelines and constraints to ensure that the total exposure ratio remains below one in areas accessible to the general public.
This method shall be validated using the approaches described in Clauses 5, 6, 7, 8 and 9 and shall take into account defined RF sources 1) and significant variables in the local physical environment
The guidelines 2) shall specify constraints
• on the influence of relevant sources on the general public access restrictions for the Equipment Under Test,
• on the influence of the Equipment Under Test on existing relevant sources general public access restrictions.
Provided these guidelines and the associated constraints are satisfied, the total exposure ratio is less than or equal to one in relevant areas where the general public has access.
1) Defined RF sources may be restricted to the EUT alone or may include specific relevant sources according to the associated constraints.
2) See Annex A for guideline examples.
The methods for calculating and measuring electromagnetic fields are influenced by the location of the investigation point in relation to the source antenna, which can be categorized into reactive near-field, radiating near-field, or far-field regions (EN 50383) In the radiating near-field and far-field, it is possible to estimate the electric field (E-field), magnetic field (H-field), or power density through calculations and measurements Conversely, in the reactive near-field, it is advisable to conduct specific absorption rate measurements in accordance with EN 50383.
The assessed total exposure ratio at each investigation point will be the highest value obtained from measurements taken at three different heights above a public walkway (see Figure 4).
Figure 4 Location of the three assessments for each point of investigation
The pre-analysis method establishes guidelines and constraints to ensure that the total exposure ratio remains below one in areas accessible to the general public.
This method shall be validated using the approaches described in Clauses 5, 6, 7, 8 and 9 and shall take into account defined RF sources 1) and significant variables in the local physical environment
The guidelines 2) shall specify constraints
• on the influence of relevant sources on the general public access restrictions for the Equipment Under Test,
• on the influence of the Equipment Under Test on existing relevant sources general public access restrictions.
Provided these guidelines and the associated constraints are satisfied, the total exposure ratio is less than or equal to one in relevant areas where the general public has access.
1) Defined RF sources may be restricted to the EUT alone or may include specific relevant sources according to the associated constraints.
2) See Annex A for guideline examples.
6 Determination of domains and relevant sources
Principle of relevance
The principle of relevance defines the criteria for determining when a radio source is significant enough to impact RF exposure assessments A radio source is deemed relevant in areas where its exposure ratio exceeds 0.05.
This principle is applied in three ways:
The objective is to establish a boundary beyond which the contribution of the Equipment Under Test to the total exposure ratio is negligible, thus not requiring consideration for compliance or its potential impact on the compliance of other sources.
• to establish if the exposure ratio from each individual radio source is relevant and needs to be considered as a contributor to the total exposure ratio;
The objective is to determine if RF fields emitted by the Equipment Under Test, when reflected off nearby structures, significantly elevate the exposure ratio within the compliance boundary of the Equipment Under Test.
Determination of domains
Relevant domain
The relevant domain will be established through the calculation or measurement methods outlined in Clauses 7 and 8 At the boundary of this domain, the exposure ratio from the Equipment Under Test must not exceed 0.05.
Once the compliance boundary is established in relation to reference levels as per EN 50383, the relevant domain boundary can be calculated by multiplying the minimum distance from the antenna's radiating part to the compliance boundary by a factor of 5 in the specified direction (Annex C).
Scatter domain
The scatter domain is defined through the calculation or measurement methods outlined in Clauses 7 and 8 or in EN 50383 It is essential that the exposure ratio of the Equipment Under Test at the scatter domain boundary remains at or below 0.1, as specified in Annex C.
Once the compliance boundary is established in relation to reference levels as per EN 50383, the scatter domain boundary can be calculated This is done by taking the minimum distance from the antenna's radiating part to the compliance boundary and multiplying it by a factor of 3 in the specified direction (Annex C).
6 Determination of domains and relevant sources
The principle of relevance defines the criteria for determining when a radio source is significant enough to impact RF exposure assessments A radio source is deemed relevant in areas where its exposure ratio exceeds 0.05.
This principle is applied in three ways:
The area beyond which the contribution of the Equipment Under Test to the total exposure ratio can be disregarded is defined, ensuring that it does not impact compliance or the compliance of other sources.
• to establish if the exposure ratio from each individual radio source is relevant and needs to be considered as a contributor to the total exposure ratio;
The objective is to determine if RF fields emitted by the Equipment Under Test, when reflected by surrounding structures, significantly elevate the exposure ratio within the compliance boundary of the Equipment Under Test.
The relevant domain will be established through the calculation or measurement methods outlined in Clauses 7 and 8 At the boundary of this domain, the exposure ratio from the Equipment Under Test must not exceed 0.05.
Once the compliance boundary is established in relation to reference levels as per EN 50383, the relevant domain boundary can be calculated by multiplying the minimum distance from the antenna's radiating part to the compliance boundary by a factor of 5 in the specified direction (Annex C).
The scatter domain is defined through the calculation or measurement methods outlined in Clauses 7 and 8 or in EN 50383 It is essential that the exposure ratio of the Equipment Under Test at the scatter domain boundary does not exceed 0.1, as specified in Annex C.
Once the compliance boundary is established in relation to reference levels as per EN 50383, the scatter domain boundary can be calculated This is done by taking the minimum distance from the antenna's radiating part to the compliance boundary and multiplying it by a factor of 3 in the specified direction (Annex C).
In countries like Germany, Italy, and Switzerland, where this standard is integrated into regulatory processes for site certification, building permits, or operational approvals, it is essential to adhere to the obligations outlined in these procedures.
NOTE As examples, the regulatory procedures in Germany, Italy and Switzerland are described in Annexes F,
Domain of investigation
The domain of investigation is the sub-domain of the relevant domain where the general public may have access (Figure 5)
Figure 5 Representation of the relevant domain, domain of investigation, scatter domain and the compliance boundary surrounding the antenna
Determination of relevant sources
Radio sources in the frequency range 100 kHz to 40 GHz that have an exposure ratio of greater than 0,05 (6.1) in the domain of investigation shall be considered a relevant source
A source is considered relevant if its domain intersects with the domain of the Equipment Under Test The determination of relevant sources will be based on measurement and calculation as outlined in Clauses 7 and 8.
A relevant source may be considered as
• combined power over bandwidth of similar sources e.g (88 108) MHz,
• the combined power from a given antenna, location or mast
Accurate estimation of radio sources requires comprehensive information gathering It is essential to identify all nearby sources and collect the necessary data for exposure assessment The following guidelines outline effective procedures for this process.
A national database recognized by the relevant licensing authority can be utilized to obtain parameters for radio sources If this database includes additional information on the Exposure Ratio from nearby radio sources related to the Equipment Under Test, such data can be incorporated into the exposure assessment.
Nearby antennas, such as broadcast masts, radars, and cellular installations, are often visible However, small, unobtrusive antennas designed to blend with their surroundings may require some effort to locate.
In some instances, measurement can be used to identify RF sources This search may be limited to frequencies below 6 GHz.
Engaging in dialogue with the responsible operator is often essential for identifying the operating parameters This information can be sourced from national administrations, regional governments, and operators who manage databases detailing local radio transmitters, or it may be directly obtained from landlords or site owners.
Use of national permit data:
In cases where information is incomplete, estimations based on license data, such as power or Effective Isotropic Radiated Power (EIRP), can be utilized as provided by the licensing authority Reasonable assumptions should be made to ensure that the exposure ratio is overestimated.
General
This section outlines alternative methods for calculating the exposure ratio, as illustrated in the flow chart in Figure 6 Calculations will be conducted under maximum operating power, simulating peak traffic conditions.
For each source, select calculation option
Determine PDMF and use modified free space approach (Clause 7.2.3.2) No
Sum Exposure Ratios estimated using calculation (Clause 7.3)
Calculation methods
Definition of equivalent free space conditions
A point of investigation is considered to be in equivalent free space conditions if there are no significant reflecting or diffracting structures present in the scatter domain of the relevant source.
Calculation methods in equivalent free space conditions
The calculation methods shall be those described in EN 50383, e.g Free space model If other methods are used, they shall be well documented and the validity demonstrated.
Calculation methods when equivalent free space conditions do not apply
Various techniques, including finite difference time domain, physical optics, uniform theory of diffraction, and geometrical optics, can be employed to accurately estimate or even overestimate electromagnetic field strength, as outlined in EN 50383.
The method used shall be well documented and validated.
The source exposure ratio can be overestimated by using the exposure ratio estimated in free space multiplied by a factor, the power density multiplication factor (PDMF) (Annex C)
The power density multiplication factor for each source shall be determined using Figure 7 and the methodology described in Figure 8.
Radio source between reflector & PI
PI between radio source & reflector
Figure 7 Configurations used to identify positions of reflectors
Non-linear polarisation or Polarisation slant to refllector?
PI betw een radio source and reflector?
Freq > 1200 MHz? radio source betw een reflector and PI?
Summation of exposure ratio estimated using calculation
Where the exposure ratio for N sources, ER i , has been determined according to 7.2.2 and 7.2.3.1 then the combined exposure ratio from all such sources, ER a is given by
1 where the exposure ratio from Msources has been determined according to 7.2.3.2.
The combined exposure ratio from all such sources, ER b is given by
ERfs i is the exposure ratio estimated in free space (7.2.2) for the i th source;
PDMF i is the power density multiplication factor for the i th source (7.2.3.2).
The exposure ratio assessed using calculation, ER calculated , is then given by b a calculated ER ER
In accordance with Clause 5, at each point of investigation, ER calculated shall be assessed in three points and the maximum value taken
General requirement
Frequency selective or broadband measurement equipment, including one or several E-field or H-field probes, can be used to determine the measured exposure ratio, ER measured
The measurement equipment must be calibrated as a complete system at the specified measurement frequencies in accordance with EN 50383, ensuring that the calibration process considers the high crest factor present in certain signals or their combinations.
When utilizing a non-isotropic probe, it is essential to assess multiple directions and evaluate isotropy For example, when employing a single dipole antenna, measurements must be conducted in three orthogonal orientations.
If an isotropic probe is used, then only a single measurement is required.
In either case, the isotropy shall be analysed according to EN 50383 and the isotropy deviation shall be less than 2 dB for frequencies higher than 110 MHz.
• the sensitivity shall be evaluated at the relevant measurement frequencies, resolution and video bandwidths;
• the minimum detection limit shall be lower than 0,05 V/m and the maximum detection limit shall be higher than 100 V/m.
• the minimum detection limit shall be lower than 1 V/m and the maximum detection limit shall be higher than 100 V/m.
Exposure ratio measurement
Basic requirements
Measurements should be conducted when the base station and associated sources are functioning at their peak emitted power, or by employing a method that allows for the extrapolation of exposure to maximum emitted power conditions, such as during maximum traffic scenarios.
For accurate measurement of exposure ratios, the choice between broadband and frequency selective equipment is crucial Frequency selective measurements typically provide a more precise estimation, while assessments using broadband probes, as outlined in section 8.2.2, tend to overestimate the exposure ratio.
There shall be a minimum of 1 m separation between the measurement probe and the operator and/or reflecting structures.
Conditions for the use of broadband measurements
A broadband probe is effective for assessing the exposure ratio and total exposure ratio when a dominant radio source is present A radio source is deemed predominant if, based on the methods outlined in section 6.3, the influence of other sources can be considered negligible.
13 dB below the level of the radio source under test b) Detecting relevant sources
A broadband probe is essential for measuring electric field strength (ER) within the sensitivity range of the equipment, up to 0.05, provided it accounts for frequency dependence in exposure limits If the instrument performs frequency-independent integration, measurements can extend to 40 GHz or the maximum frequency of a Relevant Source as specified in section 6.3 This ensures accurate assessments and prevents exposure overestimation.
If the measured value is over 13 dB below the lowest applicable exposure limit, considering traffic fluctuations and power control, the measured ER will be considered less than one.
Conditions for the use of frequency selective measurement
The field strength level measured from a radio source must account for the total signal power To ensure accurate measurements, the resolution bandwidth of the measurement system should exceed the signal's occupied bandwidth; otherwise, the contributions within the occupied bandwidth must be aggregated to determine the amplitude value.
When a signal's power is distributed across a bandwidth that exceeds the resolution bandwidth, it is essential to perform a total power summation that considers the characteristics of the resolution bandwidth filter.
The resolution bandwidth (RBW) and video bandwidth (VBW) shall be justified 4)
For signals having large crest factor, the use of a peak detector is not recommended since it leads to large bias.
Summation of exposure ratios estimated using measurement
Where the exposure ratio has been measured using a broadband approach (8.2.2), this gives
Where the exposure ratio for N sources, ERi, has been measured using a frequency selective approach (8.2.3), ER measured is given by:
In accordance with Clause 5, at each point of investigation, ER measured shall be assessed in three points and the maximum value taken.
Uncertainty
The uncertainties shall be estimated in compliance with methods described in EN 50383.
The expanded uncertainty with a confidence interval of 95 % (ISO Guide to the expression of uncertainty in measurement) shall not exceed 3 dB for power density.
In systems with multiple channels, such as FM, the exposure ratio should be estimated using a wide resolution bandwidth that encompasses all channels This means that the overall exposure ratio is the cumulative sum of the exposure ratios from each channel within the system Even if certain channels may not be significant sources when evaluated individually, this approach guarantees that the total exposure ratio remains negligible or is appropriately accounted for, in line with the specified guidelines.
4) Recommended RBW, VBW for different radio services:
Radio Services RBW (kHz) VBW (kHZ)
Each component of uncertainty must be documented with its name, probability distribution, sensitivity coefficient, and uncertainty value The findings should be organized in a table, as illustrated in Table 2 Subsequently, the combined uncertainty will be assessed using the specified formula.
2 2 where ci is the weighting coefficient (sensitivity coefficient)
The expanded uncertainty shall be evaluated using a confidence interval of 95 %.
Probability distribution Divisor c i Standard uncertainty
Drifts in output power of the EUT, probe, temperature and humidity 5 % Rectangular 3 1
Perturbation by the environment Rectangular 3 1
Contribution of post-processing Rectangular 3 1
The value of the divisor, k, depends on the calibration.
The total exposure ratio at the point of investigation is the sum of exposure ratios assessed using calculation ER calculated (7.3) and those assessed using measurementER measured (8.3).
The total exposure ratio of 4.28 is accurately determined by summing the assessed exposure ratios from the Equipment Under Test and relevant radio sources, whether through measurement or calculation.
• identify the Equipment Under Test,
• identify who has done the assessment,
• record when the assessment was performed,
• record the assessment methods used or explicitly reference such methods,
• record the relevant source considered and associated parameters,
• record calibration details for any instrumentation used,
• include the value of parameters used in the assessment and any assumptions made,
• record the results of total exposure ratio measurements and calculations including the point(s) of investigation used
The above requirements may be addressed in part by pre-analysis reports.
Examples of pre-analysis design guidelines
Purpose
This annex gives examples of design guidelines for the Equipment Under Test compliance assessment to be determined by pre-defining a set of build guidelines
• installations designed inclusive of a specified exposure ratio (ERx) for other radio sources (Clause A.2),
Installations featuring combined or merged non-compliance zones, where the exposure ratio outside these zones is less than or equal to 1, may include a designated exposure ratio allowance (ERx) for additional radio sources, as outlined in Clause A.3.
The installation is engineered to ensure that a minimum build height is upheld at all distances from the antenna that are below the boresight limit distance This includes considerations for combined or merged non-compliance zones and a defined exposure ratio allowance (ERx) for other radio sources, as outlined in Clause A.4.
• low power installation less than 10 W EIRP (Clause A.5).
Installations designed inclusive of a specified exposure ratio allowance for other
Clause 8 of EN 50383 provides methods for calculating the electromagnetic fields from antennas. Compliance to RF exposure recommendations is assured in the region around the antenna where S≤ S Limit
S (x,y,z) is the power density calculated according to EN 50383 and x,y,z are the principle dimensions around the Equipment Under Test antenna, for simplicity these are not shown in further representations of S;
S Limit is the limit value of power density
In the case of multiple emissions, where there are n contributing sources, including the equipment under test, the total power density is summed such that:
The total exposure ratio allowance of 1 can be apportioned between the Equipment Under Test and n-1 other contributing radio sources
S i and S i Limit are the power density and power density limits respectively from the ith radio source
The exposure ratio (ERx) from sources other than the Equipment Under Test can be obtained through available data, measurements, or calculations, typically ranging from 0.05 to 0.2 Elevated values are often observed in proximity to high-power broadcast transmitters and radar stations.
Therefore, in order to maintain compliance installations may be designed according to EN 50383 with S Limit modified to S Limit *(1 - ER x ).
Combined compliance boundaries
The compliance boundary of an RF source is influenced by other RF sources, as illustrated in Figures A.1 and A.2 The degree to which antenna compliance boundary A is extended by the presence of antenna B is primarily determined by their relative RF parameters, with the effective isotropic radiated power (EIRP) being the most significant factor.
The compliance boundary around Antenna A is also affected to a lesser degree by antenna C, and any other close RF sources.
When RF sources are in close proximity, the compliance boundaries they create can merge, as illustrated in Figure A.2 In such instances, the compliance boundary for the Equipment Under Test and the merged sources can be treated as a single RF source for design purposes.
CB extended due to proximity of other RF sources
Figure A.1 Compliance boundary extension due to proximity of other RF sources
CB merge due to proximity of other RF sources
Figure A.2 Compliance boundaries merging due to proximity of other RF sources
Total Compliance Boundary (combined CB )
Figure A.3 Combined compliance boundaries around antennas on a head frame.
When using a shared head frame, the compliance boundaries for each antenna can be aggregated to form a total compliance boundary The standard method for determining the combined area within this compliance boundary involves specific calculations.
Step 1 - Calculate/obtain the worst-case compliance boundary distances for the Equipment
In scenarios involving Test and various RF sources within a shared compliance boundary, it is essential to consider other cellular operators located on rooftops or masts, especially when their operational parameters and worst-case limit distances are established When multiple operators share a site, it is crucial to reach a mutual agreement on compliance boundary distances and effectively communicate this information to relevant parties, such as the site provider.
Step 2 - Determine if the antennas are sufficiently close to be considered as a single RF source.
Table A.1 presents the multiplication factors necessary to assess whether the horizontal separation between cellular transmit antennas is adequate for them to be deemed independent By applying the appropriate factor to the boresight limit distance based on the antennas' configuration, it can be determined if the antennas are independent If the horizontal separation exceeds this calculated distance or if the angular displacement surpasses the values in Table A.1, the antennas are classified as independent.
In Step 3, if the horizontal distance between the cellular antennas is less than the calculated distance or if the angular displacement is smaller than the values listed in Table A.1, the compliance boundary distances can be combined in a specific direction using designated methods.
In the radiated near-field limit distances add linearly (cylinder model)
In the far-field the following formula may be applied:
D is the total compliance boundary distance for all antennas considered; d n is the compliance boundary distance around an individual antenna.
Incorporating compliance boundary distances presumes that all antennas exhibit comparable near/far crossover characteristics However, when the near/far crossover distances of the antennas vary significantly, an iterative summing process becomes necessary This process involves calculating the power density for each antenna in both the near-field and far-field, followed by summing these power densities to determine the results at the limit distance D.
S(D) min is the minimum of the power density at distance D for each antenna, calculated in the near-field and far-field in accordance with EN 50383;
S limit is the RF compliance power density reference level.
If antennas B and C are located at a distance from antenna A that meets or exceeds the values specified in Table A.1, the non-compliance zones remain separate, allowing the Equipment Under Test (antenna A) to be considered independent.
Table A.1 Table of figures showing minimum distances separation multipliers
Figure / Orientation and antenna type Top View
Horizontal separation a multiplier (NB: must be multiplied by maximum single-operator boresight limit distance b
Omni within an arc of angle ± 45° from the boresight of a Sector antenna
Sector antenna within an arc of angle ± 45° from the boresight of a Sector antenna
Omni within an arc of angle between 45° to 90° from the boresight of a Sector antenna 45° x 3
Sector antenna within an arc of angle between 45° to 90° from the boresight of a Sector antenna 45° x 3
Sector antenna within an arc of angle
> 90° from the boresight of a Sector antenna
Omni antenna within an arc of angle > 90° from the boresight of a Sector antenna
Sector antennas should be oriented within ± 30° of each other The horizontal separation distance applies to antennas facing each other at unobstructed vertical angles of ≤ 45 degrees for antennas up to 2 m long, and ≤ 25 degrees for those over 2 m If these angle criteria are not met, the vertical separation distance for electromagnetic compatibility (EMC) must be followed The unobstructed vertical plane criteria are relevant only for horizontal separation distances up to twice the applicable limit distance of the rear antenna Additionally, the single-operator distance is defined as the greater of the two specified distances.
Installation designed so that a minimum build height is maintained at all
distances from the antenna less than the compliance boundary distance
To ensure that the exposure ratio remains at or below 1 in all areas beneath an antenna or group of antennas, the "Build Height," denoted as H, can be determined through geometric calculations.
Figure A.4 Significant parameters relating to antenna positioning and orientation
The boresight compliance boundary distance D is conservatively considered to extend from the lower and upper edges of the antenna at an angle to the horizontal, calculated as the sum of half the 3 dB beamwidth and the maximum design down tilt According to the geometry illustrated in Figure A.4, the minimum build height, H, can be determined.
T is the maximum human height (2 m); r b is the compliance boundary distance directly below the antenna, inclusive of consideration of side lobes;
D is the total boresight compliance boundary distance; Θ is the half - 3 dB beamwidth; Φ is the maximum design downtilt (electrical plus mechanical).
The horizontal compliance boundary may be conservatively maintained at D (since the horizontal compliance boundary distance is at maximum value ofDwhen tilt=0).
Compliance is assured if a minimum height of H above local ground is maintained at all distances from the antenna as far as the boresight compliance boundary distance D
The compliance boundary distance D may also take account of the case of combined compliance boundary distance as described in Figures A.2 and A.3.
Equipment Under Test with less than 10 W average EIRP
Confirmation by authority
In countries like Germany, Italy, and Switzerland, where this standard is integrated into regulatory processes for site certification, building permits, or operational approvals, compliance with these obligations is essential.
NOTE As examples, the regulatory procedures in Germany, Italy and Switzerland are described in Annexes F, G and H
Add the following new Annexes F, G and H:
Does general public have access to the volume defined by the EUT CB?
Step 1 - Determine the CB of the EUT
Step 2 - Determine the RD & DI of the EUT (clause 6)
Does the DI exist in RD?
Step 3 - Determine the SD of the EUT (clause 6) Determine the RS (clause 6)
Is there a reflecting structure in SD?
The TER may be > 1 in DI
The TER is 3 GHz
Steps Max (λ, d/40) Max (2 m, d/40) 1 m 0,5 m d is the distance (m) from the point of investigation to Relevant Source Annex D.
Border of a restricted area located in the domain of investigation (DI)
The methods for calculating and measuring electromagnetic fields are influenced by the location of the investigation point in relation to the source antenna, which can be in the reactive near-field, radiating near-field, or far-field regions (EN 50383) In the radiating near-field and far-field, it is possible to estimate the electric field (E-field), magnetic field (H-field), or power density through calculations and measurements Conversely, in the reactive near-field, it is advisable to conduct specific absorption rate measurements in accordance with EN 50383.
The assessed total exposure ratio at each investigation point will be the highest value obtained from measurements taken at three different heights above a public walkway (see Figure 4).
Figure 4 Location of the three assessments for each point of investigation
The pre-analysis method establishes guidelines and constraints to ensure that the total exposure ratio remains below one in areas accessible to the general public.
This method shall be validated using the approaches described in Clauses 5, 6, 7, 8 and 9 and shall take into account defined RF sources 1) and significant variables in the local physical environment
The guidelines 2) shall specify constraints
• on the influence of relevant sources on the general public access restrictions for the Equipment Under Test,
• on the influence of the Equipment Under Test on existing relevant sources general public access restrictions.
Provided these guidelines and the associated constraints are satisfied, the total exposure ratio is less than or equal to one in relevant areas where the general public has access.
1) Defined RF sources may be restricted to the EUT alone or may include specific relevant sources according to the associated constraints.
2) See Annex A for guideline examples.
The methods for calculating and measuring electromagnetic fields are influenced by the location of the investigation point in relation to the source antenna, which can be categorized into reactive near-field, radiating near-field, or far-field regions (EN 50383) In the radiating near-field and far-field, it is possible to estimate the electric field (E-field), magnetic field (H-field), or power density through calculations and measurements Conversely, in the reactive near-field, it is advisable to conduct specific absorption rate measurements in accordance with EN 50383.
The assessed total exposure ratio at each investigation point will be the highest value obtained from the total exposure ratios measured at three different heights above a public walkway (see Figure 4).
Figure 4 Location of the three assessments for each point of investigation
The pre-analysis method establishes guidelines and constraints to ensure that the total exposure ratio remains below one in areas accessible to the general public.
This method shall be validated using the approaches described in Clauses 5, 6, 7, 8 and 9 and shall take into account defined RF sources 1) and significant variables in the local physical environment
The guidelines 2) shall specify constraints
• on the influence of relevant sources on the general public access restrictions for the Equipment Under Test,
• on the influence of the Equipment Under Test on existing relevant sources general public access restrictions.
Provided these guidelines and the associated constraints are satisfied, the total exposure ratio is less than or equal to one in relevant areas where the general public has access.
1) Defined RF sources may be restricted to the EUT alone or may include specific relevant sources according to the associated constraints.
2) See Annex A for guideline examples.
6 Determination of domains and relevant sources
The principle of relevance defines the criteria for determining when a radio source is significant enough to impact RF exposure assessments A radio source is deemed relevant in areas where its exposure ratio exceeds 0.05.
This principle is applied in three ways:
The area beyond which the contribution of the Equipment Under Test to the total exposure ratio can be disregarded is defined, ensuring that it does not impact compliance or the compliance of other sources.
• to establish if the exposure ratio from each individual radio source is relevant and needs to be considered as a contributor to the total exposure ratio;