The talk explains basic properties of reverberation chambers and presents some exemplary practical chambers with their parameters. The normative chamber validation as well as emission measurements and immunity tests are briefly explained. Finally, advantages and disadvantages are discussed.
9953056974 Call Girls In South Ex, Escorts (Delhi) NCR.pdf
EMC Measurements in Reverberation Chambers
1. Overview and Motivation
Reverberation Chambers
EMC Measurements
in Reverberation Chambers
Mathias Magdowski
Chair for Electromagnetic Compatibility
Institute for Medical Engineering
Otto von Guericke University Magdeburg, Germany
July 22, 2020
Mathias Magdowski EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements in Reverberation Chambers
6. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Mathias Magdowski EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements 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 EMC Measurements 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:
Hans Georg Krauthäuser: “Grundlagen und Anwendungen
von Modenverwirbelungskammern”
Mathias Magdowski EMC Measurements 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:
Hans Georg Krauthäuser: “Grundlagen und Anwendungen
von Modenverwirbelungskammern”
Other standards:
ISO 11452-11:2010 (automotive)
RTCA DO-160 (aircraft)
Mathias Magdowski EMC Measurements 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 EMC Measurements in Reverberation Chambers
18. 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
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 EMC Measurements in Reverberation Chambers
19. 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 EMC Measurements in Reverberation Chambers
20. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Number of Resonant Frequencies
0 50 100 150 200 250 300
100
101
102
103
Frequency, f (in MHz)
Cumulatednumberofmodes
Figure: Cumulated number of modes for the large reverberation
chamber in Magdeburg
Mathias Magdowski EMC Measurements 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 50 100 150 200 250 300
100
101
102
103
Frequency, f (in MHz)
Cumulatednumberofmodes
Figure: Cumulated number of modes for the large reverberation
chamber in Magdeburg
Mathias Magdowski EMC Measurements in Reverberation Chambers
22. 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 EMC Measurements 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
What will cause losses?
Mathias Magdowski EMC Measurements 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?
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 EMC Measurements in Reverberation Chambers
25. 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 EMC Measurements 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
Consequences of a finite quality factor:
finite resonance magnification
field can be excited outside of the resonant frequencies
modes can overlap
Mathias Magdowski EMC Measurements in Reverberation Chambers
27. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Undermoding at “Low” Frequencies
124 124.5 125 125.5 126
10−2
10−1
100
101
Frequency, f (in MHz)
Fieldstrength(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 EMC Measurements in Reverberation Chambers
28. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Overmoding at “High” Frequencies
249 249.5 250 250.5 251
10−2
10−1
100
101
Frequency, f (in MHz)
Fieldstrength(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 EMC Measurements in Reverberation Chambers
29. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Undermoding Due to a High Quality Factor
249 249.5 250 250.5 251
10−2
10−1
100
101
Frequency, f (in MHz)
Fieldstrength(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 EMC Measurements in Reverberation Chambers
30. 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 EMC Measurements 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?
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 EMC Measurements in Reverberation Chambers
32. 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 EMC Measurements in Reverberation Chambers
33. 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 EMC Measurements in Reverberation Chambers
34. 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 EMC Measurements in Reverberation Chambers
35. 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 EMC Measurements in Reverberation Chambers
36. 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 EMC Measurements 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
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 EMC Measurements in Reverberation Chambers
38. 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 EMC Measurements in Reverberation Chambers
39. 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 EMC Measurements in Reverberation Chambers
40. 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 EMC Measurements in Reverberation Chambers
41. 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 EMC Measurements in Reverberation Chambers
42. 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 EMC Measurements in Reverberation Chambers
43. 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 EMC Measurements in Reverberation Chambers
44. 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 EMC Measurements in Reverberation Chambers
45. 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 EMC Measurements in Reverberation Chambers
46. 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 EMC Measurements in Reverberation Chambers
47. 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 EMC Measurements in Reverberation Chambers
48. 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 EMC Measurements in Reverberation Chambers
49. 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 EMC Measurements in Reverberation Chambers
50. 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 EMC Measurements in Reverberation Chambers
51. 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 EMC Measurements in Reverberation Chambers
52. 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 EMC Measurements in Reverberation Chambers
53. 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 EMC Measurements in Reverberation Chambers
54. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Mathias Magdowski EMC Measurements in Reverberation Chambers
55. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
Mathias Magdowski EMC Measurements in Reverberation Chambers
56. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
EUT: random
Mathias Magdowski EMC Measurements in Reverberation Chambers
57. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Comparison
Environment: deterministic
EUT: random
Mathias Magdowski EMC Measurements in Reverberation Chambers
58. 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 EMC Measurements in Reverberation Chambers
59. 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 EMC Measurements in Reverberation Chambers
60. 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 EMC Measurements in Reverberation Chambers
61. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Measurements With a Practical EUT
200 300 400 500 600 700 800 900 1 000
55
60
65
70
75
Frequency in MHz
FieldstrengthindBµVm−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 EMC Measurements in Reverberation Chambers
62. Overview and Motivation
Reverberation Chambers
Overview
Theoretical Fundamentals
Normative Validation and Measurements
Comparison With Other Test Environments
Measurements With a Practical EUT
200 300 400 500 600 700 800 900 1 000
55
60
65
70
75
Frequency in MHz
FieldstrengthindBµVm−1
10° steps
90° steps
Figure: Comparison of the emission measurement for different
turntable steps (Source: Matthias Hirte, OVGU)
Mathias Magdowski EMC Measurements in Reverberation Chambers
63. 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 EMC Measurements in Reverberation Chambers
64. 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 frequen-
cy” (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 EMC Measurements in Reverberation Chambers
65. 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 EMC Measurements in Reverberation Chambers
66. 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 EMC Measurements in Reverberation Chambers
67. 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 EMC Measurements in Reverberation Chambers
68. 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 EMC Measurements in Reverberation Chambers
69. 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 EMC Measurements in Reverberation Chambers
70. 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 EMC Measurements in Reverberation Chambers