ETSI TS 103 052 V1.1.1 (2011-03)

Electromagnetic compatibility and Radio spectrum Matters (ERM); Radiated measurement methods and general arrangements for test sites up to 100 GHz

DTS/ERM-TG27-013

General Information

• Status: Published
• Publication Date: 15-Mar-2011
• Technical Committee: ERM TG27 - ERM Radio Site Engineering
• Current Stage: 12 - Completion
• Due Date: 16-Mar-2011
• Completion Date: 16-Mar-2011

Standards Content (Sample)

Technical Specification
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
Radiated measurement methods and general
arrangements for test sites up to 100 GHz

2 ETSI TS 103 052 V1.1.1 (2011-03)

Reference
DTS/ERM-TG27-013
Keywords
radio, testing
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3 ETSI TS 103 052 V1.1.1 (2011-03)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions, symbols and abbreviations . 7
3.1 Definitions . 7
3.2 Symbols . 10
3.3 Abbreviations . 11
4 General measurement principles used for radiated measurements . 12
4.1 Substitution method . 12
4.1.1 Principle of the substitution measurement method . 12
4.2 Pre-Substitution method . 13
4.2.1 Principle of radiated power measurement based on site attenuation (Pre-Substitution) . 13
4.3 Field strength measurement . 15
4.3.1 Principle of the field strength measurement (CISPR 16) . 15
4.4 Field strength determination for receiver sensitivity measurements . 15
4.4.1 Method of measurement . 16
4.5 Antenna pattern measurement . 17
4.5.1 Definition . 17
4.5.2 Method of measurements . 17
4.6 Choice of test method with regard to how close the expected result is to the standard, speed, costs, etc. . 18
5 Test sites and general arrangements . 19
5.1 Open Area Test Site (OATS) . 19
5.1.1 Testing in presence of ambient interferences (Measurement of the substituted radiation power) . 20
5.1.2 Testing in presence of ambient interferences (Field strength measurement) . 20
5.2 Other test sites . 21
5.2.1 Test sites with radio absorbing material . 21
5.2.1.1 Semi-Anechoic Rooms with a conductive Ground Plane . 21
5.2.1.2 Fully Anechoic Rooms (FAR) . 22
5.2.3 Reflecting test sites . 23
5.2.3.1 Electromagnetic reverberation chambers (RVC) . 23
5.2.4 Minimum requirements for test sites for measurements above 18 GHz . 23
5.3 Antennas . 25
5.3.1 Test antenna . 25
5.3.2 Substitution antenna . 25
5.3.3 Signalling antenna . 26
6 Guidance on the use of radiation test sites . 26
6.1 Verification. 26
6.2 Preparation . 26
6.3 Power supplies (to the EUT) . 27
6.4 Settings . 27
6.5 Range length except for field strength test sites as per CISPR 16 . 27
6.6 Coupling of steering, modulation and demodulation signals . 28
6.6.1 Temporary connections and electrical lines . 28
6.6.2 Data Signals . 28
6.6.3 Speech and analogue signals . 28
6.6.3.1 Acoustic coupler description . 28
6.7 Calibration . 28
6.8 Standard test position . 29
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4 ETSI TS 103 052 V1.1.1 (2011-03)
6.9 Test fixtures . 29
6.9.1 Introduction. 29
6.9.2 Measurement procedure for transmitter tests under extreme conditions. 31
6.9.3 Measurement procedure for receiver sensitivity tests under extreme conditions . 32
6.9.4 Validation of the test-fixture in the climatic facility . 32
6.9.5 Climatic facilities for the use with a test fixture for measurements under extreme conditions . 34
6.9.6 Mode of use . 35
6.9.7 Performance limitations . 35
6.10 RF cables . 36
6.11 RF waveguides . 36
6.12 External harmonic mixers . 37
6.12.1 Introduction. 37
6.12.2 Signal identification . 38
6.12.3 Conversion loss data and measurement uncertainty . 38
6.12.4 Preamplifier . 39
6.12.5 Wave Guide Attenuators . 39
6.12.6 Measurement hints . 39
6.13 Measuring receiver . 39
7 Measurement uncertainty . 40
7.1 Introduction . 40
7.1.1 Uncertainty contributions specific to an Open Area Test Site . 40
7.1.2 Uncertainty contributions specific to an Anechoic Room with a Ground Plane . 41
7.1.3 Uncertainty contributions specific to an Anechoic Room . 41
7.2 Measurement results . 41
7.3 Measurement efficiency . 41
7.4 Maximum expanded measurement uncertainty . 41
Annex A (informative): Bibliography . 43
History . 44

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5 ETSI TS 103 052 V1.1.1 (2011-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Electromagnetic compatibility and
Radio spectrum Matters (ERM).
Introduction
The recent creation of TS 103 051 [i.1] came about because of the demand for information and guidance in the
frequency range up to 100 GHz. Whilst TS 103 051 [i.1] covers the expanded measurement uncertainty associated with
measurement activities, it became obvious that a companion document was required that deals with the corresponding
methods of measurement.
The present document can be considered as complementary to TS 103 051 [i.1] and is based on the previous
TR 102 273 [5] series of documents. It is offered as a practical guide to making radiated measurements of
electromagnetic fields at frequencies up to 100 GHz. In doing so, it has incorporated the state of the art regarding
measurement techniques available to test houses and commercial laboratories.
From an international perspective, measurements for radio testing, both radio parameters and EMC are already required
above 1 GHz, notably in the US FCC regulations (40 GHz, ITU-R spurious emissions (300 GHz) and CISPR EMC
testing (6 GHz). These extensions to the measurement frequency range necessitate a review and some level of
co-ordination to ensure that a common approach to test methods and their associated measurement uncertainty
calculations are agreed.
Contrary to the requirement for performing measurements at frequencies up to 100 GHz, the descriptions of traceable
validation or the calibration of test sites are weak and lead to larger uncertainties in the measurement results. This
document expands the information and makes recommendations for open area test sites, semi-anechoic rooms and
anechoic test chambers and their use for making radiated measurements up to 100 GHz.
Measuring receivers i.e. test receivers or spectrum analysers with coaxial inputs are commercially available for
frequencies up to about 67 GHz. The frequency range can now be extended by the use of external harmonic mixers.
These devices use an EHF local oscillator signal derived from the measuring receiver and applied to the mixing element
together with the incoming signal under investigation. The mixing element internally generates harmonics of the LO
that mix with the incoming signal thereby creating an output IF signal that is within the range of the measuring receiver.
Such devices are waveguide based and have frequency ranges matching the waveguide bands.
The present document is offered as an assistive document to ETSI standard makers. Whilst it remains the responsibility
of the individual Technical Bodies to define their own test methodologies, the present document should be considered
as a source of what is possible, practical and therefore recommended.
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6 ETSI TS 103 052 V1.1.1 (2011-03)
1 Scope
The present document provides information on general arrangements for radiated measurements from 30 MHz to
100 GHz, and guidance on the use of radiation test sites. The present document captures the state of the art regarding
radiated measurement techniques, their capabilities and associated arrangements.
Whilst it remains the responsibility of the individual technical bodies to define their own test methodologies, the present
document should be considered as a source of what is possible, practical and therefore recommended.
The basic principles of substitution, pre-substitution and field strength measurements are outlined in the present
document. The general descriptions and their calibration and validation are included for Open Area Test Sites (OATS),
Semi-Anechoic Rooms with conductive ground plane and Fully Anechoic Rooms (FAR).
Equipment and its arrangement when used to perform radiated measurements such as the following are addressed:
• Measuring receiver.
• Test antennas.
• RF cables and waveguides.
• External harmonic mixers.
The extension to the measurement frequency range necessitates some information to the radiated test methods and their
associated expanded measurement uncertainty.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] CISPR 16-1-1: "Specification for radio disturbance and immunity measuring apparatus and
methods - Part 1-1: Radio disturbance and immunity measuring apparatus - Measuring apparatus".
[2] CISPR 16-1-4: " Specification for radio disturbance and immunity measuring apparatus and
methods - Part 1-4: Radio disturbance and immunity measuring apparatus - Antennas and test sites
for radiated disturbance measurements".
[3] CISPR 16-1-5: "Specification for radio disturbance and immunity measuring apparatus and
methods - Part 1-5: Radio disturbance and immunity measuring apparatus - Antenna calibration
test sites for 30 MHz to 1 000 MHz".
[4] ETSI TR 100 028 (V1.4.1) (all parts): "Electromagnetic compatibility and Radio spectrum Matters
(ERM); Uncertainties in the measurement of mobile radio equipment characteristics".
[5] ETSI TR 102 273 (all parts) (V1.2.1): "Electromagnetic compatibility and Radio spectrum Matters
(ERM); Improvement on Radiated Methods of Measurement (using test site) and evaluation of the
corresponding measurement uncertainties".
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7 ETSI TS 103 052 V1.1.1 (2011-03)
[6] ANSI C63.5 (2006): "American National Standard for Calibration of Antennas Used for Radiated
Emission Measurements in Electro Magnetic Interference".
[7] JCGM 100:2008: "Evaluation of measurement data - Guide to the expression of uncertainty in
measurement".
[8] CISPR 16-4-2: "Specification for radio disturbance and immunity measuring apparatus and
methods - Part 4-2: Uncertainties, statistics and limit modelling - Uncertainty in EMC
measurements".
[9] ISO/IEC 17025:2005/Cor 1:2006: "General requirements for the competence of testing and
calibration laboratories".
[10] EA-4/16: "EA guidelines on the expression of uncertainty in quantitative testing".
[11] CIRSPR 16-2-3: "Specification for radio disturbance and immunity measuring apparatus and
methods - Part 2-3: Methods of measurement of disturbances and immunity - Radiated disturbance
measurements".
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TS 103 051: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Expanded
measurement uncertainty for the measurement of radiated electromagnetic fields".
[i.2] IEC 60153: "Hollow metallic waveguides".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
antenna: that part of a transmitting or receiving system that is designed to radiate or to receive electromagnetic waves
antenna factor: quantity relating the strength of the field in which the antenna is immersed to the output voltage across
the load connected to the antenna.
antenna gain: ratio of the maximum radiation intensity from an (assumed lossless) antenna to the radiation intensity
that would be obtained if the same power were radiated isotropically by a similarly lossless antenna
bit error ratio: ratio of the number of bits in error to the total number of bits
calibration: operation that, under specified conditions, in a first step, establishes a relation between the quantity values
with measurement uncertainties provided by measurement standards and corresponding indications with associated
measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a
measurement result from an indication
combining network: network allowing the addition of two or more test signals produced by different sources (e.g. for
connection to a receiver input)
NOTE: Sources of test signals are normally connected in such a way that the impedance presented to the receiver
is 50 Ω. Combining networks are designed so that effects of any intermodulation products and noise
produced in the signal generators are negligible.
correction factor: numerical factor by which the uncorrected result of a measurement is multiplied to compensate for
an assumed systematic error
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8 ETSI TS 103 052 V1.1.1 (2011-03)
confidence level: probability of the accumulated error of a measurement being within the stated range of uncertainty of
measurement
directivity: ratio of the maximum radiation intensity in a given direction from the antenna to the radiation intensity
averaged over all directions (i.e. directivity = antenna gain + losses)
duplex filter: device fitted internally or externally to a transmitter/receiver combination to allow simultaneous
transmission and reception with a single antenna connection
error of measurement (absolute): result of a measurement minus the true value of the measurand
error (relative): ratio of an error to the true value
expansion factor: multiplicative factor used to change the confidence level associated with a particular value of a
measurement uncertainty
NOTE: The mathematical definition of the expansion factor can be found in clause D.5.6.2.2 of TR 100 028 [4].
extreme test conditions: conditions defined in terms of temperature and supply voltage
NOTE: Tests are normally made with the extremes of temperature and voltage applied simultaneously. The upper
and lower temperature limits are specified in the relevant testing standard. The test report states the actual
temperatures measured.
error (of a measuring instrument): indication of a measuring instrument minus the (conventional) true value
free field: field (wave or potential) which has a constant ratio between the electric and magnetic field intensities
free space: region free of obstructions and characterized by the constitutive parameters of a vacuum
impedance: measure of the complex resistive and reactive attributes of a component in an alternating current circuit
impedance (wave): complex factor relating the transverse component of the electric field to the transverse component
of the magnetic field at every point in any specified plane, for a given mode
influence quantity: quantity which is not the subject of the measurement but which influences the value of the quantity
to be measured or the indications of the measuring instrument
intermittent operation: operation where the manufacturer states the maximum time that the equipment is intended to
transmit and the necessary standby period before repeating a transmit period
isotropic radiator: hypothetical, lossless antenna having equal radiation intensity in all directions
limited frequency range: limited frequency range is a specified smaller frequency range within the full frequency
range over which the measurement is made
NOTE: The details of the calculation of the limited frequency range are normally given in the relevant testing
standard.
maximum permissible frequency deviation: maximum value of frequency deviation stated for the relevant channel
separation in the relevant testing standard
measuring system: complete set of measuring instruments and other equipment assembled to carry out a specified
measurement task
measurement repeatability: closeness of the agreement between the results of successive measurements of the same
measurand carried out subject to all the following conditions:
- the same method of measurement;
- the same observer;
- the same measuring instrument;
- the same location;
- the same conditions of use;
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9 ETSI TS 103 052 V1.1.1 (2011-03)
- repetition over a short period of time.
measurement reproducibility: closeness of agreement between the results of measurements of the same measurand,
where the individual measurements are carried out changing conditions such as:
- method of measurement;
- observer;
- measuring instrument;
- location;
- conditions of use;
- time.
measurement result: set of quantity values being attributed to a measurand together with any other available relevant
information
measurand: quantity intended to be measured
metrological traceability: property of a measurement result whereby the result can be related to a reference through a
documented unbroken chain of calibrations, each contributing to the measurement uncertainty
noise gradient of EUT: function characterizing the relationship between the RF input signal level and the performance
of the EUT
EXAMPLE: The SINAD of the AF output signal.
nominal frequency: one of the channel frequencies on which the equipment is designed to operate
nominal mains voltage: declared voltage or any of the declared voltages for which the equipment was designed
normal test conditions: conditions defined in terms of temperature, humidity and supply voltage stated in the relevant
testing standard
normal deviation: frequency deviation for analogue signals which is equal to 12 % of the channel separation
polarization: for an electromagnetic wave, the figure traced as a function of time by the extremity of the electric vector
at a fixed point in space
quantity (measurable): attribute of a phenomenon or a body which may be distinguished qualitatively and determined
quantitatively
rated audio output power: maximum audio output power under normal test conditions, and at standard test
modulations, as declared by the manufacturer
rated radio frequency output power: maximum carrier power under normal test conditions, as declared by the
manufacturer
shielded enclosure: structure that protects its interior from the effects of an exterior electric or magnetic field, or
conversely, protects the surrounding environment from the effect of an interior electric or magnetic field
SINAD sensitivity: minimum standard modulated carrier-signal input required to produce a specified SINAD ratio at
the receiver output
stochastic (random) variable: variable whose value is not exactly known, but is characterized by a distribution or
probability function, or a mean value and a standard deviation
EXAMPLE: A measurand and the related measurement uncertainty.
test fixture: auxiliary means for determination of relative values at different temperatures for establishing a relation to
absolute values
test load: 50 Ω substantially non-reactive, non-radiating power attenuator which is capable of safely dissipating the
power from the transmitter
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10 ETSI TS 103 052 V1.1.1 (2011-03)
test modulation: test modulating signal is a baseband signal which modulates a carrier and is dependent upon the type
of EUT and also the measurement to be performed
trigger device: circuit or mechanism to trigger the oscilloscope timebase at the required instant
NOTE: It may control the transmit function or inversely receive an appropriate command from the transmitter.
uncertainty (of measurement): parameter, associated with the result of a measurement, that characterizes the
dispersion of the values that could reasonably be attributed to the measurand
uncertainty (expanded): quantity defining an interval about the result of a measurement that may be expected to
encompass a large fraction of the distribution of values that could reasonably be attributed to the measurand
wanted signal level: for conducted measurements a level of +6 dBμV emf referred to the receiver input under normal
test conditions
NOTE 1: Under extreme test conditions the value is +12 dBμV emf.
NOTE 2: For analogue measurements the wanted signal level has been chosen to be equal to the limit value of the
measured usable sensitivity. For bit stream and message measurements the wanted signal has been chosen
to be +3 dB above the limit value of measured usable sensitivity.
3.2 Symbols
For the purposes of the present document, the following symbols apply:
β 2π/λ (radians/m)
γ incidence angle with ground plane (°)
λ wavelength (m)
φ phase angle of reflection coefficient (°)
H
η 120π Ohms - the intrinsic impedance of free space (Ω)
μ permeability (H/m)
AF antenna factor of the receive antenna (dB/m)
R
AF antenna factor of the transmit antenna (dB/m)
T
AF mutual coupling correction factor (dB)
TOT
c calculated on the basis of given and measured data
C cross correlation coefficient
cross
d derived from a measuring equipment specification
D(θ,φ) directivity of the source
d distance between dipoles (m)
δ skin depth (m)
d an antenna or EUT aperture size (m)
d an antenna or EUT aperture size (m)
d path length of the direct signal (m)
dir
d path length of the reflected signal (m)
refl
E electric field intensity (V/m)
max
E calculated maximum electric field strength in the receiving antenna height scan from a half
DH
wavelength dipole with 1 pW of radiated power (for horizontal polarization) (μV/m)
max
E calculated maximum electric field strength in the receiving antenna height scan from a half
DV
wavelength dipole with 1 pW of radiated power (for vertical polarization) (μV/m)
e antenna efficiency factor
ff
φ angle (°)
Δf bandwidth (Hz)
f frequency (Hz)
G(θ,φ) gain of the source (which is the source directivity multiplied by the antenna efficiency factor)
H magnetic field intensity (A/m)
I the (assumed constant) current (A)
I the maximum current amplitude
m
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11 ETSI TS 103 052 V1.1.1 (2011-03)
k 2π/λ
k a factor from Student's t distribution
k Boltzmann's constant (1,38 x 10-23 Joules/Kelvin)
K relative dielectric constant
l the length of the infinitesimal dipole (m)
L the overall length of the dipole (m)
l the point on the dipole being considered (m)
m measured
p power
Pe probability of error n
(n)
Pp probability of position n
(n)
P antenna noise power (W)
r
P power received (W)
rec
P power transmitted (W)
t
θ angle (°)
ρ reflection coefficient
r rectangular distribution
r the distance to the field point (m)
ρ reflection coefficient of the generator part of a connection
g
ρ reflection coefficient of the load part of the connection
l
R equivalent surface resistance (Ω)
s
σ conductivity (S/m)
σ standard deviation
SNR Signal to noise ratio at a specific BER
b*
SNR Signal to noise ratio per bit
b
T antenna temperature (Kelvin)
A
u U-distribution
U the expanded uncertainty corresponding to a confidence level of x %: U = k × u
c
V received voltage for cables connected via an adapter (dBμV/m)
direct
V received voltage for cables connected to the antennas (dBμV/m)
site
W radiated power density (W/m )
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
dB decibel
emf electromotive force
ERP Effective Radiated Power
EUT Equipment Under Test
FAR Fully Anechoic Rooms
FSL Free Space Loss
IF Intermediate Frequency
LO Local Oscillator
m meter
Mu Measurement uncertainty
NSA Normalized Site Attenuation
OATS Open Area Test Site
RF Radio Frequency
RVC ReVerberation Chambers
SINAD Signal Noise And Distortion
VSWR Voltage Standing Wave Ratio
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12 ETSI TS 103 052 V1.1.1 (2011-03)
4 General measurement principles used for radiated
measurements
4.1 Substitution method
The substitution method can be used even without proven suitability of the test site since the errors of the test site at
certain frequencies are constant and become compensated by the substitution. Accuracy of the substitution
predominantly depends on the accuracy of the RF source's indicator and the exact gain specification of the substitution
antenna.
NOTE: The term "accuracy" is defined, in relation to the measured value, in clause 4.1.1 of TR 102 273 [5].
4.1.1 Principle of the substitution measurement method
When assessing the radiated power with the substitution method the peak power is evaluated. Due to a vast
compensation of the failure impacts of the "comparison test site" the Measurement uncertainty (Mu) can be significantly
reduced. Disadvantage of this method is that it causes increased time expenditure when a lot of values have to be
determined for a EUT.
On the one hand a substitution test site comprises a suitable "comparison test site" (blue boxes). This site consists of an
antenna without factors (1), whereas this antenna shall provide sufficient aperture angle, a height adjustable support (2),
an antenna cable (3) as well as an indicator (4) consisting of a measuring receiver or a spectrum analyzer or a power
meter.
EUT
Figure 1: Illustration of the first step of the substitution method
In the first step of the substitution method the maximum radiated level of an EUT is determined. This level has no unit
and does not represent a measured value. It just shows an indication value.
The substitution test site (red box) consists of an unmodulated generator, variable in frequency and power, with a power
that is traceable due to calibration or alternatively a calibrated power meter (1), a suitable 50 Ω cable with indication of
the cable loss (2), a suitable, calibrated attenuator (3) for coercive adaption to the antenna, consisting of real active
resistances, an antenna support without influence on the test result (4) as well as a standard dipole up to 1 GHz or
respectively an antenna with indication of the calibrated, isotropic gain (5).
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13 ETSI TS 103 052 V1.1.1 (2011-03)
Figure 2: Illustration of the second step of the substitution method
With respect to the frequency to be measured, in the second step the generator creates a power equivalent in the level
that corresponds to the indication value of the first step.
4.2 Pre-Substitution method
The pre-substitution method is a simplified procedure which cannot replace substitution. It is only feasible when it is
proven that the test site is suitable for the particular test frequency range in the 30 MHz to 100 GHz range. The
corresponding verification can be effected with the NSA or S procedure. This verification is more difficult on other
VSWR
test sites than the Open Area Test Site (OATS) due to resonance effects of the metal shielding in connection with the
effects of the radio absorbing materials, since in this case there are six reflecting surfaces compared to one in the OATS.
See also clause 5 of TR 102 273-2 [5].
An additional general disadvantage is, that even with a sufficient number of frequency steps it has to be interpolated
between those frequency steps which in turn leads to greater measurement uncertainty.
4.2.1 Principle of radiated power measurement based on site attenuation
(Pre-Substitution)
When assessing the radiated power by pre-substitution, besides peak power this method also allows other types of
power evaluation.
Due to the influence of the test site and measurement equipment this method has an increased measurement uncertainty
that can approximately be classified as for the field strength measurement as in CIRSPR 16-2-3 [11]. Test results close
to limits need to be reassessed and rendered more precisely with the substitution method.
The determination of site attenuation requires a suitable test site that complies with the requirements of
CISPR 16-1-4 [2]. In addition a RF source is required. This source comprises a standard dipole up to 1 GHz or
respectively an antenna with indication of the calibrated, isotropic gain (1), an antenna support without influence on the
test result (2), a suitable, calibrated attenuator (3) for coercive adaption to the antenna, consisting of real active
resistances, a suitable 50 Ω cable with indication of the cable loss (4) as well as an unmodulated generator, variable in
frequency and power, with a power that is traceable due to calibration or alternatively a calibrated power meter (5).
Furthermore power measuring instruments are required. These consist of a calibrated antenna with indication of the
antenna gain (6), a height adjustable support (7), a suitable 50 Ω cable with indication of the cable loss (8) as well as a
calibrated measuring receiver (9).
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14 ETSI TS 103 052 V1.1.1 (2011-03)
As far as possible the antenna (1) shall be mounted in the height in which the EUT will be placed for the actual
measurement according to the test specification. It shall be regarded that the polarity of both antennas used needs to be
equal. A known radiated power will then be created at the RF source. The measuring antenna will be adjusted to the
height at which the highest power is indicated at the receiver (9). This power will be noted. The difference between
transmission power and received power in dB is the site attenuation. The determination of site attenuation shall be
effected with a sufficient number of frequency steps in the observed frequency range while the values shall be noted in
a list.
Site attenuation in dB
Figure 3: Example of a test site for measurements based on site attenuation

EUT
Figure 4: Example of a test site for measurements based on site attenuation
In a real test the radiated power is determined by addition of the metered value in dB with the site attenuation in dB.
ETSI
15 ETSI TS 103 052 V1.1.1 (2011-03)
4.3 Field strength measurement
4.3.1 Principle of the field strength measurement (CISPR 16)
The measurement is effected at the field strength measuring antenna in a defined distance to the EUT (e.g. in 3 m or
10 m). During field strength assessment several uncertainties are added which result from the qualification of
normalized site attenuation of the test site within the +4 dB limit, the conversion from field strength into voltage, cables
and connections, measuring receiver, turntable, environmental influences, deviation in polarity from the EUT antenna to
the field strength measuring antenna as well as the human factor.
The maximum measurement uncertainty for field strength test sites from 30 MHz to 1 GHz in CISPR 16-4-2 [8] is
indicated with 5,2 dB.
From 1 GHz to 18 GHz the field strength test site is evaluated with an S qualification procedure that shows
VSWR
compliance with the +6 dB limit.
It shall be noted that EMC is only evaluated up to 18 GHz.

EUT
Figure 5: Example of a field strength test site (grey box)
4.4 Field strength determination for receiver sensitivity
measurements
If radiated receiver sensitivity measurements are necessary, the site on which the receiver is placed shall be suitable for
determination of field strength with the substitution method.
The test site consists of a modulated generator, variable in frequency and power (1), a suitable 50 Ω cable (2), an
antenna support (3) as well as an antenna (4).
ETSI
16 ETSI TS 103 052 V1.1.1 (2011-03)
EUT
Figure 6: Example of a set up for step 1

Figure 7: Example of a setup for step 2
4.4.1 Method of measurement
A test site according to the requirements of clause A.1 shall be selected. The requirements of clauses A.2 and A.3 shall
be regarded.
Step 1
Signal generator A shall be placed in the location of the turntable in correspondence with the EUT's antenna
polarization where possible. The EUT shall be placed in location of the test antenna and shall then be rotated in 45°
increments, starting at an arbitrary orientation. At each position, the level of the signal generator shall be decreased until
the requirements of clause E.2.1 are fulfilled. The level of the signal generator shall then be recorded.
Step 2
The EUT shall be replaced by a substitution antenna as defined in clause A.1.5. The signal generator shall be adjusted to
each of the levels as recorded in step 1 and the corresponding field strength shall be determined.
The average, E , is calculated from eight measurements of field strength, where the receiver is rotated in 45°
mean
increments, starting at an arbitrary orientation.

= 20 log
E
mean 10
i=8
∑
x
i
i=1
ETSI
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