Ecma/TC20/2009/019
DATE CIRCULATION:
2009-04-07
FROM:
P.A. Beeckman, Philips Applied Technologies
TO:
Members Ecma TC20-MM-EMF
DOC TYPE:
Company report to support the development of the Ecma MM-EMF
technical report (attached)
TITLE:
Total Radiated Power Measurement Results of Multimedia products in
Reverberation Chamber; Unintentional radiators
AUTHOR:
K. Banerjee
VERSION:
3.0, 2009-04-06
DOC ID:
EMC-09-KB-001-RRP
SUMMARY:
The worst-case Total Radiated Power (TRP) of a number of multimedia
products without intentional radiators has been measured in a
reverberation chamber (RvC) in the radiated frequency range from
80 MHz up to 6 GHz. The RvC-measurement method is a straightforward method for quick assessment of the EMF properties of products
in the radiated frequency range. From the measurement results, it can
be concluded that typical multimedia products (unintentional radiators)
radiate much less (in the mentioned frequency range) than the lowpower exclusion limit of 20 mW that can be applied to demonstrate
compliance of multimedia products against the electromagnetic field
exposure requirements.
Ecma International
Rue du Rhône 114
CH-1204 Geneva
T/F: +41 22 849 6000/01
www.ecma-international.org
For Ecma use only
Report
EMC Center
Philips Applied Technologies
To
Members Ecma-TC20-EMF-MM
Author:
K. Banerjee
HTC 26 2.024
Tel: +31 40 2746821
E-mail: konika.banerjee@philips.com
Ref: EMC-09-KB-001-RRP
Date: 2009-04-06
Total Radiated Power Measurement Results of Multimedia
products in Reverberation Chamber;
Unintentional radiators
Version:
3.0
Classification:
Date:
2009-04-06
Filename:
TRP unintentional radiators
Page 1 of 10
Contents
List of abbreviations
3
1 Introduction
1.1 Background
1.2 Approach
4 4 4 2 Total Radiated Power Measurements
2.1 Test set-up and procedure
2.2 List of equipment
2.3 Determination of maximum chamber loss factor (ACFmax)
2.4 Measurement results
2.5 Pictures of test set-up
5 5 5 6 8 9 3 Conclusion
10 4 References
10 Reference:
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EMC-09-KB-001-RRP
3.0
Page 2 of 10
List of abbreviations
CL
EMF
EUT
ECMA
MM
RvC
SAR
TRP
Reference:
Version :
Consumer Lifestyle
Electromagnetic Fields
Equipment Under Test
European Computer Manufacturer Association
Multimedia
Reverberation Chamber
Specific Absorption Rate
Total Radiated Power
EMC-09-KB-001-RRP
3.0
Page 3 of 10
1 Introduction
1.1 Background
Consumer lifestyle (CL) products have to comply with requirements for exposure to
electromagnetic fields (EMF). Since no product specific EMF standard exists for CL products,
the generic EMF standard EN62311 [1] may be applied for compliance measurements. No
technical details on EMF compliance tests are however described in [1]; this has given rise to a
need to develop a low-effort product specific standard for CL products, which is currently
being carried out under the umbrella of ECMA [2].
In [3] a detailed description is given on three issues concerning the current method of testing. It
has been proposed to apply the concept of total radiated power (TRP) measurements to CL
products as a method to determine its EMF compliance. It is stated that: If the average power
emitted by an apparatus operating in the frequency range 10 MHz – 300 GHz is less than or
equal to 20 mW, then the apparatus is deemed to comply with the basic restrictions without
further testing. The Reverberation Chamber (RvC) has been put forward to be used in the TRP
measurement method.
Based on the descriptions given in [3] the test method and test set-up for TRP measurements
have been further developed. In [4] and [5] a detailed description is given on the test set-up, the
RvC calibration method and the TRP measurement method. Additionally, automated software
programs have been developed in the frequency ranges 80 – 1000 MHz and 1 – 6 GHz for the
determination of the TRP.
TRP measurements are carried out in two ranges, namely 80 – 1000 MHz and 1 – 6 GHz. The
obtained values represent the ‘worst case estimate of the TRP’ of that range, since these values
are corrected for the maximum chamber loss factor in that range. Further details are given in
§2.3. The TRP values measured in the two ranges should be added to determine the worst case
TRP in the overall frequency range of 80 MHz up to 6 GHz.
1.2 Approach
A number of TRP measurements have been carried out using the method as described in [4].
Measurements were carried out on a range of multimedia (MM) products classified as
unintentional radiators, i.e. products which do not contain an antenna to intentionally transmit
RF power. The obtained results were analysed and compared to the TRP-limit of 20 mW.
Reference:
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Page 4 of 10
2 Total Radiated Power Measurements
2.1 Test set-up and procedure
The block diagram of the TRP measurement set-up is given in figure 1.
Reverberation Chamber
Horizontal stirrer
GPIB control
Horn
antenna
or
LogPer
antenna
Vertical stirrer
LF/HF
band-pass
filter
RMS
power
sensor
Preamplifier
Power meter
EUT
GPIB control
GPIB control
Control PC
Figure 1
TRP test set-up in RvC
Power measurements are carried out over a period of 6 minutes in continuous stirred mode
over two frequency ranges: 80 – 1000 MHz (band 1) and 1 – 6 GHz (band 2). The measured
values of power are corrected for the extra (pre-) amplification and the loss introduced by the
LF/HF band pass filter. This value is then corrected for the maximum chamber loss factor for
the average power over each band. Further details on the chamber loss factor can be found in
[4] and in §2.3.
2.2 List of equipment
The following table gives the list of equipment, type numbers/id’s and associated frequency
ranges.
Table 1 Equipment list
Reference:
Version :
No.
1.
2.
3.
4.
Description
Reverberation Chamber
LogPeriodic antenna
Horn antenna
LF Band Pass Filter
5.
HF Band Pass Filter
6.
7.
8.
Pre-amplifier
Power sensor
Power meter
EMC-09-KB-001-RRP
3.0
Type/id
ETS Lindgren (MSC14)
ETS Lindgren
EMCO 3050
Mini circuits
SHP 100+ and SLP 1000+
Mini circuits
SHP 1000+ and VLF 6000+
Miteq CE 50359
R&S NRV-Z2
R&S URV5
Frequency range
80 MHz – 18 GHz
30 MHz – 2 GHz
1 – 18 GHz
100 MHz – 1 GHz
1 – 6 GHz
100 MHz – 26 GHz
10 MHz – 18 GHz
9 kHz – 18 GHz
Page 5 of 10
2.3 Determination of maximum chamber loss factor (ACFmax)
Before TRP measurements can be carried out on actual EUTs, a Reverberation Chamber
calibration has to be performed to determine the losses which are inherently associated with the
chamber. Calibration is carried out according to [6]. A short description of the process is given
in this paragraph.
The block diagram of the calibration set-up is shown in figure 2.
Reverberation Chamber
Horizontal stirrer
GPIB control
Receive
Horn
antenna
or
Vertical stirrer
3
Transmit
Horn
antenna
1
Spectrum
analyser
Receive
LogPer
antenna
or
Transmit
LogPer
antenna
2
Dual
directional
coupler
Signal
generator
Power
sensors
Power meter
GPIB control
GPIB control
Control PC
Figure 2
Calibration test set-up in RvC
The forward and reverse power per frequency point is measured by the power meter. From
these values, the net power is calculated and recorded.
Similarly, the received power (Preceived) is measured and recorded by the spectrum analyser for
each frequency point.
The stirrers are rotated continuously for 6 minutes per frequency point. During these 6 minutes,
approximately 90 individual measurements are recorded for Pinput and Preceived.
The average input power and receive power is calculated from these values; Pinput
Preceived avg.
Reference:
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avg
and
Page 6 of 10
The chamber loss factor called as the Antenna Calibration Factor (ACF) is calculated (per
frequency point) using the following formula;
Figure 3 and figure 4 show the ACF values in the frequency range 80 – 1000 MHz and 16 GHz respectively.
ACFmax
Figure 3
ACF
80 – 1000 MHz
ACFmax
Figure 4
ACF 1 – 6 GHz
Figure 3 and 4 also show the maximum value of the ACF per frequency range.
Table 2 Maximum value of ACF per frequency range
Frequency range
80 – 1000 MHz
1 – 6 GHz
ACFmax
26.06 dB
43.75 dB
For broadband TRP measurements, the ACFmax is used as the correction factor, meaning that a
‘worst case estimate’ of the TRP is obtained.
Reference:
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Page 7 of 10
2.4 Measurement results
Measurements were carried out on a range of TV sets and monitors. The mode of operation
was chosen according to the mode in which EMC measurements were carried out. Primarily a
background measurement was done in an empty chamber (see measurement result in first row
of table 3) to determine the noise floor. For all EUTs, measurements were carried out in two
ranges (80 – 1000 MHz and 1 – 6 GHz) in stirred mode over a period of 6 minutes. From the
results given in table 3, it can be seen that the TRP levels of typical CL product (unintentional
radiators) lie far below the low-power limit of 20 mW.
Table 3 Worst-case TRP measurement results
No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
EUT
TRP in µW
80 – 1000 MHz
Background
19PFL3404H
19 inch TV set
0.01
0.203
19PFL3404D/xx
19 inch TV set
0.223
22PFL3404H/xx
22 inch TV set
0.709
22PFL3404/xx
22 inch TV set
2.016
22PFL3404D/xx
22 inch TV set
0.244
26PFL3404H/xx
26 inch TV set
10.079
32PFL5604H/xx
32 inch TV set
19.174
42PFL5604H*
42 inch TV set
0.293
42PFL5604H*
42 inch monitor
0.405
52 inch
3D monitor
17.05
TRP in µW
1 – 6 GHz
4.853
11.963
17.618
36.917
44.715
23.01
205.197
27.895
10.403
22.202
12.569
Total TRP
in µW
80 MHz – 6 GHz
4.863
12.166
17.841
37.626
46.731
23.254
215.276
47.069
10.696
22.607
29.619
Remarks
Empty RvC
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 13 set-up
Colour bar at 863.25
TV pattern generator
In CISPR 22 set-up
Connected to PC,
mouse
Scrolling H pattern
In CISPR 22 set-up
Connected to PC,
mouse
3D pattern
MHz using
MHz using
MHz using
MHz using
MHz using
MHz using
MHz using
MHz using
keyboard,
keyboard,
*The 42 inch TV set/monitor (42PFL5604H) was measured once using the CISPR13 set-up (i.e. as TV set with colour bar measurement 9) and once using the CISPR 22 set-up (i.e. as monitor, with test PC and scrolling H pattern - measurement 10).
TRP values measured in CISPR 22 set-up are slightly higher. This may be because of the presence of additional equipment
(PC, keyboard, mouse) and cables inside the chamber. See § 2.5 for pictures.
Reference:
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Page 8 of 10
The worst-case TRP in the frequency range of 80 MHz up to 6 GHz ranges from approximately
10 µW to 200 µW (which is equivalent to -20 dBm up to -7 dBm). Compared to the low-power
limit of 20 mW (13 dBm), the worst-case TRP of these MM-products is more than 20 dB
(factor 100) lower. It should be noted from the results in Table 3 that in general the higher
frequency range (1 – 6 GHz) shows a larger worst-case TRP value than the worst-case TRP
values of the lower frequency range. This is partially due to the fact that the upper frequency
range is approximately 6 times larger than the lower frequency range. Furthermore, it is likely
that the spectral content in the upper frequency range does not extend to 6 GHz, and therefore
the calculation of the worst-case TRP is overly conservative by applying the maximum ACF
value in this range (see Figure 4).
2.5 Pictures of test set-up
The following photographs give details of the setup of some EUTs and measuring equipment
inside the RvC.
LogPer antenna used in
80 – 1000 MHz range
along with LF band pass
filter and pre-amplifier
Horn antenna used in 16 GHz range along with
HF band pass filter and
pre-amplifier
32 inch TV set from front
in CISPR 13 set-up
32 inch TV set from rear
in CISPR 13 set-up
19 inch TV set on foam
tables inside RvC.
Horizontal stirrer and
receive antenna position
visible
3D monitor connected
with PC, keyboard and
mouse. 3D pattern
generated on screen.
42 inch TV set in CISPR
22 set-up. Connected to
PC, keyboard and mouse.
Scrolling H pattern
generated on screen
42 inch TV set in CISPR
22 set-up. Meandering of
connected cables at the
rear visible. Receive
antenna position visible.
Reference:
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Page 9 of 10
3 Conclusion
The developed method [3][4] of determining the worst-case TRP of products in an RvC is a
straight-forward method for quick assessment of the EMF properties of products in the radiated
frequency range (> 80 MHz). From the measurement results given in table 3, it can be
concluded that typical MM products (unintentional radiators) radiate much less than the lowpower TRP limit of 20 mW. In order to have an understanding on the entire scope of
multimedia products, as a next step, similar measurements will be carried out on products
having multiple intentional radiators.
4 References
[1]
IEC 62311 – International Standard – Assessment of electronic and electrical equipment related
to human exposure restrictions for electromagnetic fields (0 Hz – 300 GHz).
[2]
ECMA International Technical Report – ECMA TC20 2008 054 – Guide for assessment of
human exposure to electromagnetic fields from multimedia products in accordance with IEC/EN
62311.
[3]
Feasibility study to apply total radiated power measurements for EMF assessments. EMC center
memorandum EMC-08-PAB-006-MEM, Pierre Beeckman, dated 2008-09-16.
[4]
Continuation of a feasibility study to apply total radiated power measurements for EMF
assessments. EMC center memorandum EMC-08-JVDM-007-MEM, Jaco van der Merwe, dated
2008-12-17.
[5]
Reverberation Chamber Calibration Process for EMF TRP measurements – EMC center
memorandum EMC-09-KB-MEM, Konika Banerjee, dated 2008-04-01.
[6]
IEC 61000-4-21 – International standard – Testing and measurement techniques – Reverberation
Chamber test methods
Reference:
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