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Overview and Motivation
Reverberation Chambers
Well Stirred is Half Measured
EMC Tests in Reverberation Chambers
Mathias Magdowski
Chair for Electromagnetic Compatibility
Institute for Medical Engineering
Otto von Guericke University Magdeburg, Germany
October 11, 2023
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview Over Other Test Environments
Motivation
Table of Contents
Overview Over Other Test Environments
(a) Open Area Test Site (Cambridge) (b) Semi-Anechoic Chamber (Magdeburg)
(c) Fully-Anechoic Room (Gent) (d) GTEM Cell (Magdeburg)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview Over Other Test Environments
Motivation
Table of Contents
Motivation
Carl Edward Baum in Microwave Memo No. 3:
“The Microwave Oven Theorem
– All Power to the Chicken”
What is the difference between a
microwave oven and a mode stirred
chamber?
The former cooks chicken, the later
cooks electronics.
Figure: Carl Edward Baum (1940 –
2010)
Source: http://www.ece.unm.edu/summa/
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview Over Other Test Environments
Motivation
Table of Contents
1 Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Setup
Figure: Schematic setup of a reverberation chamber (top view)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Draw a Good Stirrer Design!
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Pros and Cons
Pros:
high Q −→ high E field strength with low input P
relatively low costs
statistical uniform field −→ robust tests
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Pros and Cons
Pros:
high Q −→ high E field strength with low input P
relatively low costs
statistical uniform field −→ robust tests
Cons:
statistics necessary
no statement about directivity and polarization possible
EUT loads the chamber and lowers Q
comparison with established test environments
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Setup
Figure: Typical Reverberation Chamber (IEC 61000-4-21)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Reverberation Chambers in Magdeburg
Figure: Large reverberation chamber in Magdeburg
Key figures:
built in 1998, dimensions of 7.9 m × 6.5 m × 3.5 m
first cavity resonance at 30 MHz
lowest usable frequency at 250 MHz
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Reverberation Chambers in Magdeburg
Figure: Small reverberation chamber in Magdeburg
Key figures:
built in 2003, dimensions of 1.5 m × 1.2 m × 0.9 m
first cavity resonance at 160 MHz
lowest usable frequency at 1 GHz
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Reverberation Chambers in Magdeburg
Figure: Tiny reverberation chamber in Magdeburg
Key figures:
built in 2006, dimensions of 60 cm × 58 cm × 56 cm
first cavity resonance at 360 MHz
lowest usable frequency at 2 GHz
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Literature
Generic technical standard IEC 61000-4-21:
1. Edition from 2003, 2. Edition from 2011
explains the validation and measurements
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Literature
Generic technical standard IEC 61000-4-21:
1. Edition from 2003, 2. Edition from 2011
explains the validation and measurements
Book:
John M. Ladbury, Galen H. Koepke, Dennis G. Camell: Evaluation of the NASA
Langley Research Center Mode-Stirred Chamber Facility
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Literature
Generic technical standard IEC 61000-4-21:
1. Edition from 2003, 2. Edition from 2011
explains the validation and measurements
Book:
John M. Ladbury, Galen H. Koepke, Dennis G. Camell: Evaluation of the NASA
Langley Research Center Mode-Stirred Chamber Facility
Other standards:
ISO 11452-11:2010 (automotive)
RTCA DO-160 (aircraft)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Intermediate Overview
1 Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Survey: Resonances
https://strawpoll.de/
ybe3xcz
What happens if the frequency of the excitation
exactly coincides with some eigenfrequency of
the chamber (i. e. a resonance)?
1 There will be an incredibly high field
strength!
2 This is not possible, as the frequencies
never exactly match.
3 Nothing spectacular, this is the usual
operation of a reverberation chamber.
4 There will be a large reflected power going
back from the TX antenna to the power
amplifier.
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Empty Rectangular Cavity Resonator
a
b
c
x
y
z
Cavity resonances:
f =
c0
2
s
l
a
2
+

m
b
2
+

n
c
2
l, m and n are non-negative integers, of which no more than one may be zero
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Resonant Frequencies
f in MHz l m n
29.8635 1 1 0
44.4060 2 1 0
46.8424 1 0 1
48.6416 0 1 1
49.8724 1 2 0
52.2113 1 1 1
57.2213 2 0 1
59.7270 2 2 0
61.4165 3 1 0
61.6935 2 1 1
Table: First 10 resonant frequencies of the large reverberation chamber in Magdeburg with the
dimensions of 7.9 m × 6.5 m × 3.5 m
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Number of Resonant Frequencies
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
100
101
102
103
Frequency, f (in MHz)
Cumulated
number
of
modes
Figure: Cumulated number of modes for the large reverberation chamber in Magdeburg
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Number of Resonant Frequencies
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
100
101
102
103
Frequency, f (in MHz)
Cumulated
number
of
modes
Figure: Cumulated number of modes for the large reverberation chamber in Magdeburg
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Quality Factor
Q =
ω · stored energy
average power loss
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Quality Factor
Q =
ω · stored energy
average power loss
What will cause losses?
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Quality Factor
Q =
ω · stored energy
average power loss
What will cause losses?
Losses:
within the dielectric (very small in air)
at the walls (material: copper, aluminum, steel)
by loading the chamber (scatterers as the stirrer, antennas, cables, EUT, monitoring
equipment, . . . )
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Bandwidth of the Resonant Frequencies
Relation between bandwidth and quality factor:
Q =
Resonant Frequency
Bandwidth
=
1
relative Bandwidth
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Bandwidth of the Resonant Frequencies
Relation between bandwidth and quality factor:
Q =
Resonant Frequency
Bandwidth
=
1
relative Bandwidth
Consequences of a finite quality factor:
finite resonance magnification
field can be excited outside of the resonant frequencies
modes can overlap
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Undermoding at “Low” Frequencies
124 124.2 124.4 124.6 124.8 125 125.2 125.4 125.6 125.8 126
10−2
10−1
100
101
Frequency, f (in MHz)
Field
strength
(normalized)
Superposition
Figure: Schematic modal structure in the large reverberation chamber in Magdeburg around
125 MHz at a quality factor of Q = 1000
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Overmoding at “High” Frequencies
249 249.2 249.4 249.6 249.8 250 250.2 250.4 250.6 250.8 251
10−2
10−1
100
101
Frequency, f (in MHz)
Field
strength
(normalized)
Superposition
Figure: Schematic modal structure in the large reverberation chamber in Magdeburg around
250 MHz at a quality factor of Q = 1000
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Undermoding Due to a High Quality Factor
249 249.2 249.4 249.6 249.8 250 250.2 250.4 250.6 250.8 251
10−2
10−1
100
101
Frequency, f (in MHz)
Field
strength
(normalized)
Superposition
Figure: Schematic modal structure in the large reverberation chamber in Magdeburg around
250 MHz at a quality factor of Q = 10 000
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Cavity Resonator −→ Reverberation Chamber
How to stir the field?
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Cavity Resonator −→ Reverberation Chamber
How to stir the field?
Changes of the electromagnetic boundary conditions:
mechanical stirrer
moving walls
replacing the transmitting antenna
switching between several antennas
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Cavity Resonator −→ Reverberation Chamber
How to stir the field?
Changes of the electromagnetic boundary conditions:
mechanical stirrer
moving walls
replacing the transmitting antenna
switching between several antennas
Narrow band frequency changes:
only for immunity testing
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Vibrating Intrinsic Reverberation Chamber
(a) Demonstration with neon tubes (b) In-situ test on a ship
Source: Prof. Leferink, University of Twente and THALES, Netherlands
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Oscillating Wall Stirrer
Figure: Reverberation chamber with an oscillating wall stirrer at the Laboratory of Electromagnetic
Compatibility, School of Mechanical Engineering, Southeast University, Nanjing, China
Source: https://dx.doi.org/10.1109/TEMC.2020.2983981
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Terminology
Reverberation chamber =
mode-stirred chamber
mode-tuned chamber
overmoded cavity
reverberating enclosure
electrically large, complex cavity
Modenverwirbelungskammer
Feldvariable Kammer
. . .
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Statistical Properties of the Field
Homogeneity:
independence of location
free placement of the EUT in the working volume
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Statistical Properties of the Field
Homogeneity:
independence of location
free placement of the EUT in the working volume
Isotropy:
independence of direction
free alignment of the EUT and attached cables
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Statistical Properties of the Field
Homogeneity:
independence of location
free placement of the EUT in the working volume
Isotropy:
independence of direction
free alignment of the EUT and attached cables
Ergodicity:
interchangeability of different statistical ensembles
e. g. stirrer positions, spatial points, neighboring frequencies, etc.
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Intermediate Overview
1 Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Chamber Field Uniformity and Loading Validation
Goal:
verification of a sufficiently small field inhomogeneity in the working volume
determination of the lowest usable frequency (LUF)
for the empty and maximum loaded chamber
Maximum chamber loading verification:
simulate the chamber loading by the EUT
using a sufficient amount of absorbers
EUT loading ≤ maximum loading
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Chamber Validation With the EUT in Place
Goal:
analyze the loading by the EUT
loading ≤ maximum loading
Same procedure as empty chamber validation with the following simplifications:
no field probe measurements
only one locations of the reference antenna
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Radiated Immunity Testing
Determination of the chamber input power:
setting of the required field strength ETest
feeding of a certain forward power
PInput ∼ E2
Test (1)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Radiated Immunity Testing
Determination of the chamber input power:
setting of the required field strength ETest
feeding of a certain forward power
PInput ∼ E2
Test (1)
Proportionality factor results from:
empty chamber validation
validation with the EUT in place
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Performing an Immunity Test
Preparation:
remove unnecessary absorbing materials → high Q
no wooden tables, carpets, wall and floor coverings
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Performing an Immunity Test
Preparation:
remove unnecessary absorbing materials → high Q
no wooden tables, carpets, wall and floor coverings
Procedure:
logarithmic frequency spacing with 100 frequencies/decade
same minimum numbers of stirrer steps as during validation
appropriate dwell time per frequency and stirrer step
no stirring in conjunction with swept frequency testing
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Radiated Emission Measurement
Based on the measurement of the average received power:
Prad =
ηTX · PAveRec
CVF
(2)
Variables:
ηTX efficiency of the transmitting antenna (75 % to 90 %)
PAveRec average received power at the reference antenna
CVF chamber validation factor from the validation with the EUT (switched off) in place
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Survey: Other Measurements
https://strawpoll.de/
r27a16r
What is difficult to be measured in a
reverberation chamber?
1 Shielding effectiveness of cables,
connectors, waveguides and passive
microwave components
2 Shielding effectiveness of gaskets and
materials
3 Modulated-signal measurements of
wireless devices
4 Antenna efficiency
5 Antenna directivity
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Intermediate Overview
1 Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
What is Meant by the “Electric Field”?
c
E
H
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
What is Meant by the “Electric Field”?
c
E
H
Linearly polarized plane wave with the amplitude E0:
amplitude of the Cartesian field component is E0
total electric field strength is E0
minimum, average and maximum field strength is E0
minimum, average and maximum squared magnitude is E2
0
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
What is Meant by the “Electric Field”?
c
E
H
Linearly polarized plane wave with the amplitude E0:
amplitude of the Cartesian field component is E0
total electric field strength is E0
minimum, average and maximum field strength is E0
minimum, average and maximum squared magnitude is E2
0
This is not valid for a reverberant field!
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Electrical Size of an Equipment Under Test
a
Definition as k · a:
k: wave number, k = 2πf
c = 2π
λ
a: radius of the smallest sphere surrounding the
EUT
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Electrical Size of an Equipment Under Test
a
Definition as k · a:
k: wave number, k = 2πf
c = 2π
λ
a: radius of the smallest sphere surrounding the
EUT
Questions:
What belongs to the EUT (case, cables, . . . )?
Which line length has to be considered?
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Electrical Small EUTs
Condition: k · a ≤ 1
Figure: Radiation pattern of a small dipole (Source: Wikipedia)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Electrical Large EUTs
Condition: k · a  1
Figure: Radiation pattern (planar cut) of a practical EUT (Source: Magnus Höijer, FOI)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Electrical Large EUTs
Condition: k · a  1
Figure: Radiation pattern (planar cut) of a practical EUT (Source: Magnus Höijer, FOI)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Electrical Large EUTs
Condition: k · a  1
Figure: Radiation pattern (planar cut) of a practical EUT (Source: Magnus Höijer, FOI)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Transition From Electrically Small to Electrically Large
Frequency f Wave Number k k · a Radius a Diameter d
in GHz in m−1 in cm in cm
0.03 0.6 1.0 159.2 318.3
0.10 2.1 1.0 47.8 95.5
0.20 4.2 1.0 23.9 47.7
0.50 10.5 1.0 9.6 19.1
1.0 20.9 1.0 4.8 9.6
2.0 41.9 1.0 2.4 4.8
5.0 104.7 1.0 0.9 1.9
10.0 209.4 1.0 0.5 1.0
Table: Example values for an electrical EUT size of k · a = 1 (Source: Perry Wilson, NIST)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Sampling
Frequency f Wave Number k Radius a k · a Orientations
in GHz in m−1 in cm
0.03 0.6 0.25 0.2 12
0.10 2.1 0.25 0.5 12
0.20 4.2 0.25 1.1 13
0.50 10.5 0.25 2.6 48
1.0 20.9 0.25 5.2 152
2.0 41.9 0.25 10.5 522
5.0 104.7 0.25 26.2 2951
10.0 209.4 0.25 52.4 11 385
Table: Number of independent orientation for an object with 50 cm diameter (Source: Perry
Wilson, NIST)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
EUT: random
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
EUT: random
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
EUT: random
Environment: random
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
EUT: random
Environment: random
EUT: deterministic
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Measurements With a Practical EUT
(a) in the reverberation chamber (b) in the semi-anechoic chamber
Figure: Utilized equipment under test (Source: Matthias Hirte, OVGU)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Measurements With a Practical EUT
200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1 000
55
60
65
70
75
Frequency in MHz
Field
strength
in
dB
µV
m
−1
Measurement in the semi-anechoic chamber
Measurement in the reverberation chamber
Figure: Comparison of the emission measurement in different environments, directivity = 1
(Source: Matthias Hirte, OVGU)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Measurements With a Practical EUT
200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1 000
55
60
65
70
75
Frequency in MHz
Field
strength
in
dB
µV
m
−1
10◦ steps
90◦ steps
Figure: Comparison of the emission measurement for different turntable steps (Source: Matthias
Hirte, OVGU)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Semi-Anechoic vs. Reverberation Chamber
Property Semi-Anechoic Reverberation
Chamber Chamber
Field plane wave multiple reflections
Polarization linear unknown
Correlation length very long short (λ
2 )
Incident direction known all directions
Field impedance 377 Ω unknown
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
SAC vs. GTEM vs. RVC
Property Semi-Anechoic
Chamber
GTEM Reverberation
Chamber
f Range above 30 MHz
(10 m test distance)
from 0 Hz above “Lowest usable
frequency” (LUF)
Problems test in the
near field
at low f
standing
waves at
medium f
no statistic
uniform field
a low f
Test Time increases
with f
increases
with f
stays constant
EUT V large small medium
Costs high low low
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
More Fundamental Question
What is a good measurand for emission?
field strength in V m−1 (in a certain distance)
power flux density in W m−2 (in a certain distance)
total radiated power W (independent of the distance)
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
More Fundamental Question
What is a good measurand for emission?
field strength in V m−1 (in a certain distance)
power flux density in W m−2 (in a certain distance)
total radiated power W (independent of the distance)
In which environment is the measurement performed?
reflection-free environment
environment with reflections
highly reflective environment
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Final Question
All Power to the Chicken?
PInput = PWall + PStirrer + PChicken
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Final Question
All Power to the Chicken?
PInput = PWall + PStirrer + PChicken
PWall = 0
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Final Question
All Power to the Chicken?
PInput = PWall + PStirrer + PChicken
PWall = 0
PStirrer = 0
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Final Question
All Power to the Chicken?
PInput = PWall + PStirrer + PChicken
PWall = 0
PStirrer = 0
PInput = PChicken
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Thank you very much for your attention!
Are there more questions?
Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers

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Well Stirred is Half Measured - EMC Tests in Reverberation Chambers

  • 1. Overview and Motivation Reverberation Chambers Well Stirred is Half Measured EMC Tests in Reverberation Chambers Mathias Magdowski Chair for Electromagnetic Compatibility Institute for Medical Engineering Otto von Guericke University Magdeburg, Germany October 11, 2023 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 2. Overview and Motivation Reverberation Chambers Overview Over Other Test Environments Motivation Table of Contents Overview Over Other Test Environments (a) Open Area Test Site (Cambridge) (b) Semi-Anechoic Chamber (Magdeburg) (c) Fully-Anechoic Room (Gent) (d) GTEM Cell (Magdeburg) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 3. Overview and Motivation Reverberation Chambers Overview Over Other Test Environments Motivation Table of Contents Motivation Carl Edward Baum in Microwave Memo No. 3: “The Microwave Oven Theorem – All Power to the Chicken” What is the difference between a microwave oven and a mode stirred chamber? The former cooks chicken, the later cooks electronics. Figure: Carl Edward Baum (1940 – 2010) Source: http://www.ece.unm.edu/summa/ Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 4. Overview and Motivation Reverberation Chambers Overview Over Other Test Environments Motivation Table of Contents 1 Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 5. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Setup Figure: Schematic setup of a reverberation chamber (top view) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 6. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 7. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Draw a Good Stirrer Design! Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 8. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Pros and Cons Pros: high Q −→ high E field strength with low input P relatively low costs statistical uniform field −→ robust tests Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 9. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Pros and Cons Pros: high Q −→ high E field strength with low input P relatively low costs statistical uniform field −→ robust tests Cons: statistics necessary no statement about directivity and polarization possible EUT loads the chamber and lowers Q comparison with established test environments Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 10. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Setup Figure: Typical Reverberation Chamber (IEC 61000-4-21) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 11. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Reverberation Chambers in Magdeburg Figure: Large reverberation chamber in Magdeburg Key figures: built in 1998, dimensions of 7.9 m × 6.5 m × 3.5 m first cavity resonance at 30 MHz lowest usable frequency at 250 MHz Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 12. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Reverberation Chambers in Magdeburg Figure: Small reverberation chamber in Magdeburg Key figures: built in 2003, dimensions of 1.5 m × 1.2 m × 0.9 m first cavity resonance at 160 MHz lowest usable frequency at 1 GHz Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 13. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Reverberation Chambers in Magdeburg Figure: Tiny reverberation chamber in Magdeburg Key figures: built in 2006, dimensions of 60 cm × 58 cm × 56 cm first cavity resonance at 360 MHz lowest usable frequency at 2 GHz Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 14. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Literature Generic technical standard IEC 61000-4-21: 1. Edition from 2003, 2. Edition from 2011 explains the validation and measurements Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 15. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Literature Generic technical standard IEC 61000-4-21: 1. Edition from 2003, 2. Edition from 2011 explains the validation and measurements Book: John M. Ladbury, Galen H. Koepke, Dennis G. Camell: Evaluation of the NASA Langley Research Center Mode-Stirred Chamber Facility Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 16. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Literature Generic technical standard IEC 61000-4-21: 1. Edition from 2003, 2. Edition from 2011 explains the validation and measurements Book: John M. Ladbury, Galen H. Koepke, Dennis G. Camell: Evaluation of the NASA Langley Research Center Mode-Stirred Chamber Facility Other standards: ISO 11452-11:2010 (automotive) RTCA DO-160 (aircraft) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 17. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Intermediate Overview 1 Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 18. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Survey: Resonances https://strawpoll.de/ ybe3xcz What happens if the frequency of the excitation exactly coincides with some eigenfrequency of the chamber (i. e. a resonance)? 1 There will be an incredibly high field strength! 2 This is not possible, as the frequencies never exactly match. 3 Nothing spectacular, this is the usual operation of a reverberation chamber. 4 There will be a large reflected power going back from the TX antenna to the power amplifier. Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 19. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Empty Rectangular Cavity Resonator a b c x y z Cavity resonances: f = c0 2 s l a 2 + m b 2 + n c 2 l, m and n are non-negative integers, of which no more than one may be zero Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 20. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Resonant Frequencies f in MHz l m n 29.8635 1 1 0 44.4060 2 1 0 46.8424 1 0 1 48.6416 0 1 1 49.8724 1 2 0 52.2113 1 1 1 57.2213 2 0 1 59.7270 2 2 0 61.4165 3 1 0 61.6935 2 1 1 Table: First 10 resonant frequencies of the large reverberation chamber in Magdeburg with the dimensions of 7.9 m × 6.5 m × 3.5 m Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 21. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Number of Resonant Frequencies 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 100 101 102 103 Frequency, f (in MHz) Cumulated number of modes Figure: Cumulated number of modes for the large reverberation chamber in Magdeburg Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 22. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Number of Resonant Frequencies 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 100 101 102 103 Frequency, f (in MHz) Cumulated number of modes Figure: Cumulated number of modes for the large reverberation chamber in Magdeburg Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 23. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Quality Factor Q = ω · stored energy average power loss Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 24. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Quality Factor Q = ω · stored energy average power loss What will cause losses? Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 25. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Quality Factor Q = ω · stored energy average power loss What will cause losses? Losses: within the dielectric (very small in air) at the walls (material: copper, aluminum, steel) by loading the chamber (scatterers as the stirrer, antennas, cables, EUT, monitoring equipment, . . . ) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 26. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Bandwidth of the Resonant Frequencies Relation between bandwidth and quality factor: Q = Resonant Frequency Bandwidth = 1 relative Bandwidth Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 27. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Bandwidth of the Resonant Frequencies Relation between bandwidth and quality factor: Q = Resonant Frequency Bandwidth = 1 relative Bandwidth Consequences of a finite quality factor: finite resonance magnification field can be excited outside of the resonant frequencies modes can overlap Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 28. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Undermoding at “Low” Frequencies 124 124.2 124.4 124.6 124.8 125 125.2 125.4 125.6 125.8 126 10−2 10−1 100 101 Frequency, f (in MHz) Field strength (normalized) Superposition Figure: Schematic modal structure in the large reverberation chamber in Magdeburg around 125 MHz at a quality factor of Q = 1000 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 29. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Overmoding at “High” Frequencies 249 249.2 249.4 249.6 249.8 250 250.2 250.4 250.6 250.8 251 10−2 10−1 100 101 Frequency, f (in MHz) Field strength (normalized) Superposition Figure: Schematic modal structure in the large reverberation chamber in Magdeburg around 250 MHz at a quality factor of Q = 1000 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 30. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Undermoding Due to a High Quality Factor 249 249.2 249.4 249.6 249.8 250 250.2 250.4 250.6 250.8 251 10−2 10−1 100 101 Frequency, f (in MHz) Field strength (normalized) Superposition Figure: Schematic modal structure in the large reverberation chamber in Magdeburg around 250 MHz at a quality factor of Q = 10 000 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 31. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Cavity Resonator −→ Reverberation Chamber How to stir the field? Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 32. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Cavity Resonator −→ Reverberation Chamber How to stir the field? Changes of the electromagnetic boundary conditions: mechanical stirrer moving walls replacing the transmitting antenna switching between several antennas Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 33. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Cavity Resonator −→ Reverberation Chamber How to stir the field? Changes of the electromagnetic boundary conditions: mechanical stirrer moving walls replacing the transmitting antenna switching between several antennas Narrow band frequency changes: only for immunity testing Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 34. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Vibrating Intrinsic Reverberation Chamber (a) Demonstration with neon tubes (b) In-situ test on a ship Source: Prof. Leferink, University of Twente and THALES, Netherlands Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 35. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Oscillating Wall Stirrer Figure: Reverberation chamber with an oscillating wall stirrer at the Laboratory of Electromagnetic Compatibility, School of Mechanical Engineering, Southeast University, Nanjing, China Source: https://dx.doi.org/10.1109/TEMC.2020.2983981 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 36. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Terminology Reverberation chamber = mode-stirred chamber mode-tuned chamber overmoded cavity reverberating enclosure electrically large, complex cavity Modenverwirbelungskammer Feldvariable Kammer . . . Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 37. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Statistical Properties of the Field Homogeneity: independence of location free placement of the EUT in the working volume Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 38. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Statistical Properties of the Field Homogeneity: independence of location free placement of the EUT in the working volume Isotropy: independence of direction free alignment of the EUT and attached cables Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 39. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Statistical Properties of the Field Homogeneity: independence of location free placement of the EUT in the working volume Isotropy: independence of direction free alignment of the EUT and attached cables Ergodicity: interchangeability of different statistical ensembles e. g. stirrer positions, spatial points, neighboring frequencies, etc. Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 40. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Intermediate Overview 1 Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 41. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Chamber Field Uniformity and Loading Validation Goal: verification of a sufficiently small field inhomogeneity in the working volume determination of the lowest usable frequency (LUF) for the empty and maximum loaded chamber Maximum chamber loading verification: simulate the chamber loading by the EUT using a sufficient amount of absorbers EUT loading ≤ maximum loading Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 42. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Chamber Validation With the EUT in Place Goal: analyze the loading by the EUT loading ≤ maximum loading Same procedure as empty chamber validation with the following simplifications: no field probe measurements only one locations of the reference antenna Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 43. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Radiated Immunity Testing Determination of the chamber input power: setting of the required field strength ETest feeding of a certain forward power PInput ∼ E2 Test (1) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 44. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Radiated Immunity Testing Determination of the chamber input power: setting of the required field strength ETest feeding of a certain forward power PInput ∼ E2 Test (1) Proportionality factor results from: empty chamber validation validation with the EUT in place Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 45. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Performing an Immunity Test Preparation: remove unnecessary absorbing materials → high Q no wooden tables, carpets, wall and floor coverings Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 46. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Performing an Immunity Test Preparation: remove unnecessary absorbing materials → high Q no wooden tables, carpets, wall and floor coverings Procedure: logarithmic frequency spacing with 100 frequencies/decade same minimum numbers of stirrer steps as during validation appropriate dwell time per frequency and stirrer step no stirring in conjunction with swept frequency testing Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 47. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Radiated Emission Measurement Based on the measurement of the average received power: Prad = ηTX · PAveRec CVF (2) Variables: ηTX efficiency of the transmitting antenna (75 % to 90 %) PAveRec average received power at the reference antenna CVF chamber validation factor from the validation with the EUT (switched off) in place Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 48. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Survey: Other Measurements https://strawpoll.de/ r27a16r What is difficult to be measured in a reverberation chamber? 1 Shielding effectiveness of cables, connectors, waveguides and passive microwave components 2 Shielding effectiveness of gaskets and materials 3 Modulated-signal measurements of wireless devices 4 Antenna efficiency 5 Antenna directivity Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 49. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Intermediate Overview 1 Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 50. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments What is Meant by the “Electric Field”? c E H Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 51. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments What is Meant by the “Electric Field”? c E H Linearly polarized plane wave with the amplitude E0: amplitude of the Cartesian field component is E0 total electric field strength is E0 minimum, average and maximum field strength is E0 minimum, average and maximum squared magnitude is E2 0 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 52. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments What is Meant by the “Electric Field”? c E H Linearly polarized plane wave with the amplitude E0: amplitude of the Cartesian field component is E0 total electric field strength is E0 minimum, average and maximum field strength is E0 minimum, average and maximum squared magnitude is E2 0 This is not valid for a reverberant field! Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 53. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Electrical Size of an Equipment Under Test a Definition as k · a: k: wave number, k = 2πf c = 2π λ a: radius of the smallest sphere surrounding the EUT Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 54. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Electrical Size of an Equipment Under Test a Definition as k · a: k: wave number, k = 2πf c = 2π λ a: radius of the smallest sphere surrounding the EUT Questions: What belongs to the EUT (case, cables, . . . )? Which line length has to be considered? Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 55. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Electrical Small EUTs Condition: k · a ≤ 1 Figure: Radiation pattern of a small dipole (Source: Wikipedia) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 56. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Electrical Large EUTs Condition: k · a 1 Figure: Radiation pattern (planar cut) of a practical EUT (Source: Magnus Höijer, FOI) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 57. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Electrical Large EUTs Condition: k · a 1 Figure: Radiation pattern (planar cut) of a practical EUT (Source: Magnus Höijer, FOI) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 58. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Electrical Large EUTs Condition: k · a 1 Figure: Radiation pattern (planar cut) of a practical EUT (Source: Magnus Höijer, FOI) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 59. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Transition From Electrically Small to Electrically Large Frequency f Wave Number k k · a Radius a Diameter d in GHz in m−1 in cm in cm 0.03 0.6 1.0 159.2 318.3 0.10 2.1 1.0 47.8 95.5 0.20 4.2 1.0 23.9 47.7 0.50 10.5 1.0 9.6 19.1 1.0 20.9 1.0 4.8 9.6 2.0 41.9 1.0 2.4 4.8 5.0 104.7 1.0 0.9 1.9 10.0 209.4 1.0 0.5 1.0 Table: Example values for an electrical EUT size of k · a = 1 (Source: Perry Wilson, NIST) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 60. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Sampling Frequency f Wave Number k Radius a k · a Orientations in GHz in m−1 in cm 0.03 0.6 0.25 0.2 12 0.10 2.1 0.25 0.5 12 0.20 4.2 0.25 1.1 13 0.50 10.5 0.25 2.6 48 1.0 20.9 0.25 5.2 152 2.0 41.9 0.25 10.5 522 5.0 104.7 0.25 26.2 2951 10.0 209.4 0.25 52.4 11 385 Table: Number of independent orientation for an object with 50 cm diameter (Source: Perry Wilson, NIST) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 61. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Comparison Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 62. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Comparison Environment: deterministic Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 63. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Comparison Environment: deterministic EUT: random Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 64. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Comparison Environment: deterministic EUT: random Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 65. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Comparison Environment: deterministic EUT: random Environment: random Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 66. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Comparison Environment: deterministic EUT: random Environment: random EUT: deterministic Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 67. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Measurements With a Practical EUT (a) in the reverberation chamber (b) in the semi-anechoic chamber Figure: Utilized equipment under test (Source: Matthias Hirte, OVGU) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 68. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Measurements With a Practical EUT 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1 000 55 60 65 70 75 Frequency in MHz Field strength in dB µV m −1 Measurement in the semi-anechoic chamber Measurement in the reverberation chamber Figure: Comparison of the emission measurement in different environments, directivity = 1 (Source: Matthias Hirte, OVGU) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 69. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Measurements With a Practical EUT 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1 000 55 60 65 70 75 Frequency in MHz Field strength in dB µV m −1 10◦ steps 90◦ steps Figure: Comparison of the emission measurement for different turntable steps (Source: Matthias Hirte, OVGU) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 70. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Semi-Anechoic vs. Reverberation Chamber Property Semi-Anechoic Reverberation Chamber Chamber Field plane wave multiple reflections Polarization linear unknown Correlation length very long short (λ 2 ) Incident direction known all directions Field impedance 377 Ω unknown Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 71. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments SAC vs. GTEM vs. RVC Property Semi-Anechoic Chamber GTEM Reverberation Chamber f Range above 30 MHz (10 m test distance) from 0 Hz above “Lowest usable frequency” (LUF) Problems test in the near field at low f standing waves at medium f no statistic uniform field a low f Test Time increases with f increases with f stays constant EUT V large small medium Costs high low low Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 72. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments More Fundamental Question What is a good measurand for emission? field strength in V m−1 (in a certain distance) power flux density in W m−2 (in a certain distance) total radiated power W (independent of the distance) Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 73. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments More Fundamental Question What is a good measurand for emission? field strength in V m−1 (in a certain distance) power flux density in W m−2 (in a certain distance) total radiated power W (independent of the distance) In which environment is the measurement performed? reflection-free environment environment with reflections highly reflective environment Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 74. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Final Question All Power to the Chicken? PInput = PWall + PStirrer + PChicken Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 75. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Final Question All Power to the Chicken? PInput = PWall + PStirrer + PChicken PWall = 0 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 76. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Final Question All Power to the Chicken? PInput = PWall + PStirrer + PChicken PWall = 0 PStirrer = 0 Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 77. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Final Question All Power to the Chicken? PInput = PWall + PStirrer + PChicken PWall = 0 PStirrer = 0 PInput = PChicken Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers
  • 78. Overview and Motivation Reverberation Chambers Overview Theoretical Fundamentals Normative Validation and Measurements Comparison With Other Test Environments Thank you very much for your attention! Are there more questions? Mathias Magdowski (Otto von Guericke University Magdeburg, Germany) Well Stirred is Half Measured – EMC Tests in Reverberation Chambers