Basic standard for the calculation and measurement of electromagnetic field strength and SAR related to human exposure from radio base stations and fixed terminal stations for wireless telecommunication systems (110 MHz - 40 GHz)
This basic standard applies to radio base stations and fixed terminal stations for wireless telecommunication systems as defined in Clause 4, operating in the frequency range 110 MHz to 40 GHz. The objective of the standard is to specify, for such equipment, the method for assessment of compliance distances according to the basic restrictions (directly or indirectly via compliance with reference levels) related to human exposure to radio frequency electromagnetic fields.
Grundnorm für die Berechnung und Messung der elektromagnetischen Feldstärke und SAR in Bezug auf die Sicherheit von Personen in elektromagnetischen Feldern von Mobilfunk-Basisstationen und stationären Teilnehmergeräten von schnurlosen Telekommunikationsanlagen (110 MHz bis 40 GHz)
Norme de base pour le calcul et la mesure des champs électromagnétiques et SAR associés à l'exposition des personnes provenant des stations de base radio et des stations terminales fixes pour les systèmes de radiotélécommunications (110 MHz - 40 GHz)
Osnovni standard za izračunavanje in merjenje moči elektromagnetnega polja in SAR v povezavi z izpostavljenostjo ljudi sevanjem zaradi radijskih baznih postaj in fiksnih terminalskih postaj za brezžične telekomunikacijske sisteme (110 MHz - 40 GHz)
Ta osnovni standard velja za radijske bazne postaje in fiksne terminalske postaje za brezžične telekomunikacijske sisteme, kot je določeno v Klavzuli 4, ki delujejo v frekvenčnem razponu od 100 MHz do 40 GHz. Namen tega standarda je za takšno opremo določiti metodo za ocenjevanje dogovorjene razdalje v skladu z osnovnimi omejitvami (neposredno ali posredno s skladnostjo z referenčnimi stopnjami), povezanimi s človeško izpostavljenostjo elektromagnetnim poljem radijske frekvence.
Standards Content (sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.*+]Grundnorm für die Berechnung und Messung der elektromagnetischen Feldstärke und SAR in Bezug auf die Sicherheit von Personen in elektromagnetischen Feldern von Mobilfunk-Basisstationen und stationären Teilnehmergeräten von schnurlosen Telekommunikationsanlagen (110 MHz bis 40 GHz)Norme de base pour le calcul et la mesure des champs électromagnétiques et SAR associés à l'exposition des personnes provenant des stations de base radio et des stations terminales fixes pour les systèmes de radiotélécommunications (110 MHz - 40 GHz)Basic standard for the calculation and measurement of electromagnetic field strength and SAR related to human exposure from radio base stations and fixed terminal stations for wireless telecommunication systems (110 MHz - 40 GHz)33.070.01Mobilni servisi na splošnoMobile services in general17.220.20Measurement of electrical and magnetic quantitiesICS:Ta slovenski standard je istoveten z:EN 50383:2010/AC:2013SIST EN 50383:2010/AC:2013en01-september-2013SIST EN 50383:2010/AC:2013SLOVENSKISTANDARD
SIST EN 50383:2010/AC:2013
Corrigendum to EN 50383:2010 English version ___________ Due to a mistake in the numbering, the whole Clause 6 needs to be renumbered. Please note that the content of Clause 6 has not been modified. Replace the entire Clause 6 by the following: 6 Electromagnetic field measurement 6.1 Introduction This section describes the measurement procedures that may be used to assess, at points of investigation, the electromagnetic field components (E and H and therefore the power density) radiated by antennas. The field measurements can be obtained either by surface or volume scanning.
The methods used are to measure directly or indirectly the E-field or H-field strength, deduce the field distribution for a given input power and frequency. 6.2 Surface scanning method 6.2.1 Introduction
Methods to perform surface scanning could be, but are not limited to, far-field, compact range, and planar, cylindrical or spherical near-field as long as the methodology is accurately defined and the uncertainty criteria (Annexes B and E) are fulfilled.
6.2.2 Spherical scanning method Measurements of electric field amplitude, phase and polarisation are made at sufficient points on the surface of a sphere surrounding the EUT to establish the parameters to model a set of isotropic sources on that surface that will produce at the point of investigation the same field as the EUT. To make this valid, the scanned spherical surface shall contain all the relevant energy that is radiated from the EUT. The parameters of this set of isotropic-radiators are then used to calculate the field at the points of investigation required in order to establish the compliance boundary.The principle steps are summarised in Figure 1. SIST EN 50383:2010/AC:2013
Start Return field value at point of investigation Chart 5.1
Establish characteristics of equivalent isotropic-radiators on surface of radius Rmes and determine E/H at point of investigation scaled for appropriate EUT power level(s) (6.2.4) Review uncertainty (6.2.5) Determine scanning radius & spherical sampling angles, set up test equipment (6.2.2) Measure phase & amplitude and polarization of EUT signals over a spherical surface of radius Rmes. (6.2.3)
Figure 1 – Outline of the surface scanning methodology 184.108.40.206 Measurement equipment 220.127.116.11.1 General description The surface scanning consists of an Equipment Under Test (EUT) mounted on an azimuthal positioner and the probe(s) mounted on a support structure at distance Rmes from the EUT. This method requires the ability to measure the phase of the signal. Detection shall consist of either one probe moved mechanically along the structure or one probe array switched electronically in order to perform an angular elevation scan of the electromagnetic fields.
Alternatively, the EUT can be moved to different elevation angles by means of an additional elevation positioner. The near-field antenna measurement system shall be configured according to Figure 2. SIST EN 50383:2010/AC:2013EN 50383:2010/AC:2013
positioning system Vector - receiver Positioner
control synthesizer Data acquisition
control Probe EUT Y Z X Amplifier (0, 0, 0) Rmes
Figure 2 – Block diagram of the near-field antenna measurement system
The following equipment is required:
- anechoic chamber; - electric probe(s) (antenna(s)); - support structure for probe(s); - supporting structure; - vector receiver; - synthesiser and amplifier(s); - probe positioning system or probe array controller system; - EUT positioning system.
A computer controls the measurement equipment located in the anechoic chamber. The computer shall be placed so as not to influence the measurements.
The test shall be performed using probe antennas providing electric field measurements. The probe antennas shall be accurately positioned to measure the electric field distributions in a spherical surface around the EUT.
The measurement shall be carried out with a minimum of reflections from the environment in order to simulate free space conditions. 18.104.22.168.2 Scanning equipment: positioning and orientation requirements
22.214.171.124.2.1 General criteria The measurement system shall be able to scan a specified spherical surface of the test environment. In order to provide sufficient data required combined with the resolution and accuracy needed for post-processing; − the radius Rmes between the reference point of the EUT (0, 0, 0) and the probe(s) at each of the measurement points shall be chosen to satisfy the radius criteria (ref. 126.96.36.199.2.2) and shall be established withindegrees [see reference Clause B.3].
SIST EN 50383:2010/AC:2013
EN 50383:2010/AC:2013 − the measurement system shall be able to provide measurements every δθ in elevation and δφ in azimuth to satisfy the sampling criterion as defined in 188.8.131.52.2.3 with an angular accuracy better than 0,5 degrees.
The sampling of the whole spherical surface is achieved through the rotation of the EUT or the structure supporting the probe(s). Several types of positioning systems are proposed in Annex B. 184.108.40.206.2.2 Radius criteria Rmes the distance between the reference point of the EUT at origin of rotation and the measurement probe(s) shall be the greater of
− Rmin in order to minimise the impact of the non-radiating near fields where Rmin depends upon the maximum dimension of the EUT and Figure 3; and − the distance required to ensure that the probes and measurement equipment is operating within their calibrated level range for the power specifications of the EUT.-===0° Rmin
-===90° a Reference point of the EUT
-===0° a Rmin
-===90° Reference point of the EUT
a = the minimum radius of a sphere, centred at reference point, that will encompass the EUT. Figure 3 – Minimum radius constraint 220.127.116.11.2.3 Sampling criterion The sampling criterion (also commonly called Nyquist criteria) requires a maximum angular spacing of the measurement points of λ/2 over the sphere circumscribing the EUT with radius Rmes. The angles δφ (azimuth) and δθ (elevation) between adjacent measurements depend on the system but shall comply with the constraints of Figure 4.SIST EN 50383:2010/AC:2013
EN 50383:2010/AC:2013 /- mesR2λδφ≤ mesR2λδθ≤
Figure 4 – Maximum angular sampling spacing constraint 18.104.22.168.2.4 Constraints on EUT dimensions for specific measurement system
Given the radius Rmes equal to the constant distance between the center of rotation of the EUT and the probe(s), and given the number N equidistant sampling points in elevation or azimuth, each of the above criteria leads to a maximum dimension Dmax for the EUT:)12(2)(2maxmax−<−<πλλNDandRDmes Where
aD2max=(see Figure 3) Depending on the operating frequency, the maximum size will be limited by the most constraining of both criteria (i.e. the first criteria at lower frequencies and the second criteria at higher frequencies). 22.214.171.124.3 Measurement probe The probe or probe array shall be designed and dimensioned such as not to disturb the electromagnetic fields generated by the EUT. The probe(s) gain shall be calibrated with a measurement uncertainty less than ± 0,5 dB. The probe shall be able to provide orthogonal polarisation with cross-polar isolation better than 30 dB. Alternatively, a second scan with a probe rotated by 90 degrees could detect the cross-polar values. Typically open-ended waveguides (OEW) or crossed dipoles are used, as they have a well-defined radiation characteristic and a low influence on the EUT. 126.96.36.199.4 Supporting structure The antenna shall be mounted on a dielectric holder fixed on the positioning system. The holder shall be made of low conductivity and low relative permittivity material(s): tan(δ) ≤ 0,05 and εr ≤ 5. Alternatively, the antenna may be mounted on a metallic pipe mast, if this is the normal operating situation of the antenna. If the mounting situation differs from a free-space equivalent, this has to be documented in the measurement results. The antenna shall be mounted so that the reference point (0, 0, 0) is in the centre of the sphere.SIST EN 50383:2010/AC:2013
EN 50383:2010/AC:2013 188.8.131.52.5 Vector-receiver The dynamic range shall be more than 90 dB. To minimise external interference, a phase locked loop (PLL) system is preferred. The receiver shall be able to measure the magnitude and phase for every detection point. 184.108.40.206 Anechoic chamber The level of perturbation due to reflections and/or noise, shall not exceed - 30 dB of the incident field where measurements are made.
If no PLL-system is used, the shielding level of the anechoic chamber enclosure should be better than
50 dB at the measurement frequencies. The size and cover materials of the anechoic chamber shall be evaluated in order to minimise the level of perturbation due to reflections. The methodology to evaluate the chamber reflectivity is given in Clause B.3. Ambient temperature shall be in the range of 10 °C to 30 °C and shall not vary by more than ± 5 °C during the test. 220.127.116.11 Measurement protocol 18.104.22.168.1 Calibration of the test facility Four calibrations of the near field spherical test facility shall be performed: - polarisation calibration; - amplitude and phase calibration (uniformity between probe(s)); - gain calibration; - electrical noise evaluation.
The measurement equipment shall be calibrated as a complete system at the appropriate frequencies according to the methodology defined in Annex B. Calibration guidelines are given in Clause B.6. 22.214.171.124.2 Test to be performed The test shall be performed at the fixed power matched to the detection range of the measurement equipment.
Post-processing will derive the results at the desired input power values. For multi-mode and multi-band EUTs, all the previous tests shall be performed in each operating transmitting band (see 5.2). 126.96.36.199.3 General requirements for the Equipment Under Test (EUT) Surface scanning shall be used to define the EUT electromagnetic field parameters. The EUT shall be fed with frequencies comparable to normal configurations. A generator may replace the transmitter providing the input power to the EUT. Power scaling is addressed by the post-processing in 188.8.131.52. For a base station with an integrated antenna, special care has to be taken to phase-lock the system. SIST EN 50383:2010/AC:2013
EN 50383:2010/AC:2013 184.108.40.206.4 Measurement procedure 220.127.116.11.4.1 Basic test configuration The basic test configuration corresponds to an initial angle φ = φ0 (azimuth). The angular scan θ (elevation) shall start at one of the edges of the circular path and be incremented by a value δθ. The angular scan in elevation shall be performed along the whole circular path. At each θi = θi-1 + δθ position of the probe(s), the received or emitted signal shall be recorded. The basic test configuration will be repeated for each azimuthal increment δφ. 18.104.22.168.4.2 Pre-test procedure Check if the detection probe(s) can accept the power levels radiated during the measurements. Calibrate the electric and/or magnetic probe(s) in gain. Alternatively, confirm that the absolute values of the electromagnetic fields can be derived from the measurement data over the whole sphere. Check the frequencies for the measurement. A minimum of 3 frequencies are required: Fc, Fmin and Fmax with: Fccentre frequency; Fmin lower edge frequency; Fmax
upper edge frequency. Check the value of δφ, φmax, δθ, θmin, θmax, Rmes with: δφ azimuthal increment; φmax maximum azimuthal angle value from the reference; δθ elevation increment; θmin lower edge angle of the circular elevation path; θmax upper edge angle of the circular elevation path; Rmes radius of the scan in elevation; Dmax largest dimension of the EUT (= 2a, Figure 3); λ wavelength. Confirm that the total contribution of interferences and reflected signals is less than – 30 dB below the incident signal.
22.214.171.124.4.3 Test procedure - Confirm proper operation of the probe(s), measurement system and instrumentation. - Mount the EUT in the measurement configuration. - Configure the EUT for optimum output power, at the desired frequency and for the desired operating modes. - Position (or configure) the probe(s) at the initial measurement location. - Perform an initial elevation scan at the reference azimuth position and store the data. SIST EN 50383:2010/AC:2013
EN 50383:2010/AC:2013 - The detected electromagnetic fields amplitude and phase in both polarisations shall be output in ISU (International System Unit, V/m for electric field and A/m for magnetic field). Any conversion shall be done using the appropriate factors delivered from the calibration.
- Measure and acquire the electromagnetic fields distribution. - The EUT or the probe(s) are moved incrementally in azimuth with ∆φ angle step around a vertical axis that corresponds also to a symmetry axis for the sphere to be scanned. - Repeat the electromagnetic fields measurement until φi = φmax (with φi = φi-1 + δφ, with imin = 1). - After measurements, perform again a final elevation scan at the reference azimuth position and compare the data with the initial elevation scan. Verify that the final values at the maximum levels are within 5 % of the initial values (influence of the drift due to surrounding equipment and environment). - If the drift is greater than 5 %, repeat the measurements.
126.96.36.199 Post-processing 188.8.131.52.1 General The electromagnetic field values shall be obtained by applying a post-processing technique on the set of measured near field data (see Clauses B.4 and B.5). 184.108.40.206.2 Determining electromagnetic field values outside the scanned surface The electromagnetic fields from the EUT shall be modelled by a number of isotropic sources radiating from the scanned surface. At a point of investigation, the vector sum of the fields radiated by these sources is the same as from the EUT. The input to this model is the tangential electromagnetic field measured on the surface surrounding the EUT. The electromagnetic field values shall be calculated for points of investigation outside the scanned surface for the EUT as described in the Clause B.4. 220.127.116.11.3 Determining electromagnetic field values within the scanned surface The electromagnetic field values shall be calculated for points of investigation inside the volume surrounded by the scanned surface but outside the minimum sphere surrounding the EUT (see
Clauses B.4 and B.5). 18.104.22.168.4 Scaling measurements to a given input power The calculated E-field (resp. H-field), Eo (resp. Ho), is obtained for a given input power Po. As the E-field (resp. H-field) is proportional to the square root of the input power, the E-field (H-field), E (resp. H) for another input power P is given by: ooEPPE=
ooHPPH= Where a number of frequencies may be operated simultaneously on one or more bands, scaling of the E2, H2 and S values shall be applied linearly on each band separately according to the number of equal powered transmit frequencies on each band. 22.214.171.124 Uncertainty estimation 126.96.36.199.1 General requirements The assessment of uncertainty in the measurement of the electromagnetic fields values shall be based on the general rules provided by the ISO/IEC Guide 98-3. An evaluation of type A as well as type B of the standard uncertainty shall be used. SIST EN 50383:2010/AC:2013
EN 50383:2010/AC:2013 When a Type A analysis is performed, the standard uncertainty (uj) shall be derived from the estimate from statistical observations. When type B analysis is performed, uj comes from the upper (a+) and lower (a-) limits of the quantity in question, depending on the distribution law defining a = (a+ - a-)/2, then: − Rectangular law: 3aui= − Triangular law: 6aui= − Normal law: kaui= where k is a coverage factor
− U-shaped (asymmetric): 2aui= 188.8.131.52.2 Components contributing to uncertainty 184.108.40.206.2.1 Contribution of the measurement equipment 220.127.116.11.2.1.1 Calibration of the measurement equipment A protocol for evaluation of sensitivity (or calibration) is given in Annex B including an approach to uncertainty assessment. The uncertainty in the sensitivity shall be evaluated assuming a normal probability distribution. 18.104.22.168.2.1.2 Probe linearity The receiver and probe linearity shall be assessed according to the protocol defined in Annex B. A correction shall be performed to establish linearity. The uncertainty is considered after this correction. The uncertainty due to linearity shall be evaluated assuming it has a rectangular probability distribution. 22.214.171.124.2.1.3 Measurement device The uncertainty contribution from the measurement device (e.g. vector receiver) shall be assessed with reference to its calibration certificates. The uncertainty due to the measurement device shall be evaluated assuming a normal probability distribution. 126.96.36.199.2.1.4 Electrical Noise This is the signal detected by the measurement system even if the EUT is not transmitting. The sources of these signals include RF noise (lighting systems, the scanning system, grounding of the laboratory power supply, etc.), electrostatic effects (movement of the probe, people walking, etc.) and other effects (light detecting effects, temperature, etc.). The noise level shall be determined by three different coarse scans with the RF source switched off or with an absorbing load connected to the output of the transmitter. None of the evaluated points shall exceed - 30 dB of the lowest incident field being measured. Within this constraint, the uncertainty due to noise shall be neglected. 188.8.131.52.2.1.5 Integration time The integration time shall not introduce additional error if the EUT emits a continuous wave (CW) signal. This uncertainty depends on the signal characteristics and must be evaluated prior to any electromagnetic fields measurements. If a non-CW signal is used, then the uncertainty introduced must be taken into account in the global uncertainty assessment. The uncertainty due to integration time shall be evaluated assuming it has a normal probability distribution. SIST EN 50383:2010/AC:2013
EN 50383:2010/AC:2013 184.108.40.206.2.1.6 Contribution of the power chain The mismatch in the power chain leads to an uncertainty in the evaluation of the emitted power from the power measured by the power meter. See Annex B for an evaluation of this uncertainty in a typical case. 220.127.116.11.2.2 Contribution of the mechanical constraint 18.104.22.168.2.2.1 Mechanical constraints of the positioning system The mechanical constraints of the positioning system introduce uncertainty to the electromagnetic fields measurements through the accuracy and repeatability of positioning. These parameters shall be assessed with reference to the positioning system’s specifications and the uncertainty they introduce shall be neglected provided that the specifications comply with the criteria defined for the equipment. 22.214.171.124.2.2.2 Matching between probe and EUT reference points
Before each scan the alignment between position of the probe and the EUT shall be verified using three reference points. 126.96.36.199.2.3 Contribution of physical parameters
188.8.131.52.2.3.1 Drift in input power of the EUT, probe, temperature and humidity The drift due to electronics of the EUT and the measurement equipment, as well as temperature and humidity, are controlled by the first and last step of the measurement process defined in the measurement procedure and the resulting error is less than ± 5 %. The uncertainty shall be evaluated assuming a rectangular probability distribution. 184.108.40.206.2.3.2 Perturbation of the environment The perturbation of the environment results from various contributing factors: − reflection of wave in the laboratory; − influence of the EUT and probe(s) positioners; − influence of cables and equipment’s; − background level of electromagnetic fields.
220.127.116.11.2.4 Contribution of post-processing This is the uncertainty due to the post-processing applied to the measured data. The post-processing covers a series of mathematical operations to transform the electromagnetic fields measured over a spherical surface into the electromagnetic fields inside or outside of a volu...