utilizing reverberation chambers as a versatile test...
TRANSCRIPT
BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Utilizing Reverberation Chambers as a Versatile Test Environment for Assessing the Performance of
Components and Systems
Dennis LewisThe Boeing Company
Technical Fellow
RF / Microwave and Antenna Metrology
P.O. Box 3707 MC 19-LL
Seattle WA, 98124-2207
2BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Growing need to evaluate the EM environment
http://www.businessinsider.com/r-faster-wi-fi-on-flights-leads-to-battle-in-the-sky-2014-14
Certification
System performance prediction/validation
Model Validation
Portable Electronic devices
Wireless Sensor Networks
Overview
3BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Overview
Some Complex Environments
– Tunnels
– Ships
– Buildings
– Aircraft
– Factories
http://www.theguardian.com
http://hothardware.com/News/Gogo-Inflight-Internet-
Turns-1-Looks-To-Bring-WiFi-To-More-Planes/
http://www.forbes.com
http://xtreamblu.com/the-way-to-expand-
your-wifi-signal-for-larger-office-buildings/
4BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Component Shielding
– Aircraft Shielding
– Bulk Absorption
– Field Mapping
– Wireless propagation measurements
5BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
What is a Reverberation Chamber?
Shielded enclosure / cavity in which the test electromagnetic environment is statistically:
– Isotropic
– Randomly polarized
– Homogeneous
http://www.ccohs.ca/oshanswers/phys_agents/microwave_ovens.html
222
150)(
H
h
W
w
L
lMHzflwh
Permitted Modes
222
110
011150)(
HWLMHzf
Lowest allowable mode
6BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Independent Samples
* Independent (non-correlated) and complex cavity modal structures key to reverberation chamber operation.
– Provides variability in cavity field structure necessary to obtain isotropy and random polarization.
– Necessary for statistical analysis of data sets
* Boundary conditions at successive tuner positions may be correlated
– Tuner dimensions too small with respect to:
Wavelength
Chamber dimensions
– Tuner geometry too symmetric
– Tuner step size too small
What is a Reverberation Chamber?
7BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
What is a Reverberation Chamber?
8BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Measured MS data from Small Met Chamber @ 3 GHz…
Take this data at each frequency of interest
What is a Reverberation Chamber?
9BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Mean Norm Power (mW)
What is a Reverberation Chamber?
CDF (Linear)
0
0.2
0.4
0.6
0.8
1
1.2
0 2 4 6 8
Data
CD
F
DATA
Theoretical
10BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Mean Norm Power (dB)
What is a Reverberation Chamber?
CDF (Log)
0
0.2
0.4
0.6
0.8
1
1.2
-20 -15 -10 -5 0 5 10
Data
CD
F (
Lo
g)
DATA
Theoretical
11BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
What is a Reverberation Chamber?
NIST Technical Note 1508
“Evaluation of the NASA
Langley Research Center
mode-Stirred Chamber
Facility”
12BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
NASA Glen Research Facility
(100 ft Diameter 120 ft. Tall)
What is a Reverberation Chamber?
http://en.wikipedia.org/wiki/File:Magdeburg-reverberation_chamber.jpg
13BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
What is a Reverberation Chamber?
Photos courtesy of ETS-Lindgren
14BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
737-400 Inside Paint Hangar
What is a Reverberation Chamber?
767-400 Inside Paint Hangar
15BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Reverb chamber
Main passenger cabin
Paint hangar
What is a Reverberation Chamber?
16BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Component Shielding
– Aircraft Shielding
– Bulk Absorption
– Field Mapping
– Wireless propagation measurements
17BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Background
Mechanical Mode Stir (MS)
– First proposed in 1968 as a statistical approach to field evaluation in shielded enclosures.
– Excitation of an electrically large, high-Q enclosure establishes a complex, random EM field.
– Perturbation of this field – by an electrically large, conductive paddle wheel for mechanical stir – results in a statistically uniform field.
– Investigated by Boeing in 1993 as a method for evaluating aircraft shielding.
– Used for HIRF testing in 1998 to support 757-300 cert.
“Small Metrology Chamber”
18BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Background
(cont.)
Frequency Stir (FS)
– Equivalency to mechanical mode stirring, first suggested in 1989.
– Field perturbation accomplished by changing the frequency of the excitation source.
– Frequency stir by the method of superimposed band-limited, white Gaussian noise (BLWGN) established in 1991 – adopted by Boeing a few years later and referred to as Gaussian Frequency Stir (GFS) method.
– GFS proposed as a viable approach for 757-300 HIRF testing.
– GFS used for 767-400 HIRF testing in 2000.
19BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Motivation for Alternative Mode
Stir Method
Why do we need another mode stir measurement method??
– Mechanical stir is very time (and therefore $$) intensive – must wait for complete paddle rotation, measuring the field after each small change in paddle position, at each frequency being measured.
– Effective stirring with paddles can be a major concern with abnormally shaped cavities (i.e. a passenger cabin with seats & overhead bins).
– GFS is equipment intensive = costly to maintain, difficult / costly to move around, higher measurement uncertainties.
– GFS is a broadband measurement which reduces achievable dynamic range.
– Loose statistical data with GFS.
GFS -- Gain speed vs. mechanical stir, but…
take some performance hits & loose statistical data!
20BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Motivation for Alternative Mode
Stir Method (cont.)
GFS is “equipment intensive”…
GFS Block Diagram
Moving GFS equipment
around aircraft…
21BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Motivation for Alternative Mode
Stir Method (cont.)
GFS measured data and processing…
GFS method provides only the frequency stirred data – the average field values.
Further data processing and statistical analysis not possible.
22BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
– The Discrete Frequency Stir (DFS) technique allows for better, faster, cheaper mode stir...
–Electrical perturbation of cavity fields (no mechanical paddle need for stirring) – effected by frequency stepping a CW excitation source (narrow-band measurement = better dynamic range).
–“Frequency stir” by averaging over stirring bandwidth – typically use 100 or 200 MHz stirring bandwidth above 1 GHz (need to consider sample size and frequency resolution)
–Simple setup based on Agilent 8362 Precision Network Analyzer (PNA) – easy to move around large test article and easy to transport to remote test site
–Fast data acquisition (50 to 80% faster than GFS) – reduce test time, save $$
–Discrete measurement at each frequency step provides statistical data
Discrete Frequency Stirring
23BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
DFS measured data and processing… Statistical Analyses
Measurement of discrete data samples
allows for further processing and
statistical analysis
24BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
Important characteristics to monitor with DFS:
– Field Uniformity – variation in average field values within a given cavity
Critical to measurement uncertainty
Driven by number (Nind) of independent resonant modes excited within the stirring bandwidth (BWstir) [7]
For a given cavity, total number (N) of modes within stirring bandwidth can be determined from Weyl’s approximation as…
Need to account for mode overlap due to non-zero resonant mode bandwidth (BWQ) [7]
In practice, Nind will be limited as…
stirBWfc
VN 2
3
8
Q
fBWQ
Q
stirind
BW
BWN
25BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
Important characteristics to monitor with DFS:
– Sample independence
Affects field uniformity as discussed on previous slide
Necessary for statistical analysis of data sets
Determined by Pearson’s r autocorrelation check
where the x’s represent a data set and the y’s represent the same
data set shifted by one so that x2 has become y1 and x3 has
become y2, etc.
Uncorrelated when r is less than 1/e
i
i
i
i
i
ii
yyxx
yyxx
r22 )()(
))((
26BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
– Statistical Analysis…
To assess conformity of measured fields to theoretical field distributions for reverberation chambers.
For a given frequency, only data samples within the stirring bandwidth are used for statistical analysis.
Theoretical reverb chamber field distributions well established in literature: magnitude of individual field components (Ex, Ey, or Ez) is chi-distributed with 2 degrees of freedom; measured power is chi-square distributed with 2 degrees of freedom [8], [9].
Chi-square probability distribution function (PDF) is:
where σ is the std dev of underlying normal distributions [8].
22/
22
1)(
pepf
27BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
– Statistical Analysis (cont.)…
Goodness of fit tests used to compare measured data distributions to theoretical distribution…
–Chi-square test – calculate chi square statistic for assessment of binned, normalized data verses an integration of the theoretical probability distribution function
–K-S test – assessment of maximum deviation from the theoretical cumulative distribution function
Independent samples necessary for statistical analysis
28BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
As an example, look at data from the Small Metrology Chamber comparing Mode Tuning to DFS measurement technique
– Chamber dimensions were 1.77 x 1.52 x 2.29 meters (length x width x height)
– Resonant mode bandwidth was estimated to be less than 1 MHz across the 1-18 GHz measurement range
– Frequency step size of 1.1 MHz was used, providing 95 measurement samples within stirring bandwidth of 100 MHz
– Measurement samples verified to be independent
– 1 Transmit, 3 Receive positions measured
– Uniformity was ±1 dB
29BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
Small Metrology Chamber measured data:
30BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
To compare, Small Met Chamber field distribution using MT:
Chi-square Test K-S Test
Ave. norm DMAX = 0.56Ave. χ2 = 0.84
32% of data sets showed
χ2 < 0.65 (90% CL)
(Statistical data at 3 GHz shown; analysis done every 1, 2,…18 GHz)
χ2 = 0.40norm DMAX = 0.51
31BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Discrete Frequency Stirring
Small Met Chamber field distribution using DFS:
Chi-square Test K-S Test
(Statistical data at 5 GHz shown; analysis done every 1, 2,…18 GHz)
χ2 = 0.46 norm DMAX = 0.50
Ave. norm DMAX = 0.53Ave. χ2 = 0.84
50% of data sets showed
χ2 < 0.65 (90% CL)
32BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Measured data across 12” x 12” grid
Discrete Frequency Stirring
33BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Component Shielding
– Aircraft Shielding
– Bulk Absorption
– Field Mapping
– Wireless propagation measurements
34BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
40 GHz250 MHz200 MHz
TEM Cell
Reverberation Chamber
Anechoic Chamber
Overlap for method
comparison
Metrology Applications of Reverberation
Chambers
35BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
TEM Cell
Meter
Volts
d
V
d
RPE
• Transverse Electromagnetic Mode of
Propagation (primary mode)
• Allow higher order modes of propagation at
higher frequencies (TE, TM)
• Work very well at low Frequencies
Metrology Applications of Reverberation
Chambers
36BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Gain Extrapolation Range
Metrology Applications of Reverberation
Chambers
37BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Optimal Distance determination for measurement point
7
7.5
8
8.5
9
9.5
10
10.5
0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20
Distance (m)
Fie
ld (
V/m
)
Optimal M easurement
Location
Chamber
Reflections
Metrology Applications of Reverberation
Chambers
38BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Reverb Chamber Method…
Metrology Applications of Reverberation
Chambers
39BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Stepper Motor
EUT Monitor
Tuner / Paddle
RF Source
Power Meter
Coupler
Spectrum/Network
Analyzer
Computer
Working
Volume
>/4 from
Boundaries
Metrology Applications of Reverberation
Chambers
40BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
21
MeasR
A CAS CAS Ant
PP
2 2
21
2 2
22 12 21 11 22 11
ij
(1 )
1 ( )
Reflection coefficient of standard sensor
S S-parameter data for cable adapter combination
Sen
CAS
Sen Sen
Sen
S
S S S S S S
155
2T rE P
45r rE P
Reverberation Chamber
Block Diagram
Chamber Walls
Sensor
Antenna
ΓCAS
CAS
Measurement Plane 1
Measurement Plane 2
Cable Adapter
ΓAnt ΓSen
A
Metrology Applications of Reverberation
Chambers
41BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Adapt
Horn
2
12
2
22
COR
SP =
1- S
Network
Analyzer
3115 drHorn adapt
wg
P
P
Antenna Efficiency
Metrology Applications of Reverberation
Chambers
42BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Antenna Efficiencies
84%
86%
88%
90%
92%
94%
96%
98%
100%
8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0
GHz
Eff
icie
ncy
Dbl. Ridge
x-Band Horn
Avg. = 88.4%
Field
Uniformity
+/- 3.0%Avg. = 96.7%
Antenna Efficiency
Antenna Efficiency
43BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Antenna Efficiency
Two-antenna approach
HOLLOWAY, CL., SHAH, HA., PIRKL, RJ., YOUNG, WF., HILL, DA., and LADBURY, JM., Reverberation chamber techniques for
determining the radiation and total efficiency of antennas, IEEE Trans. Antennas Propag., Apr. 2012, vol. 60 no. 4, pp. 1758-1770.
Total Efficiency Radiation Efficiency
44BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Probe Calibration Summary
X-Axis
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1 3 5 7 9 11 13 15 17
Reverb
Anechoic
Manuf.
Antenna Efficiency
45BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Component Shielding
– Aircraft Shielding
– Bulk Absorption
– Field Mapping
– Wireless propagation measurements
46BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Factors in Electromagnetic Compatibility
An effective EMC approach controls:
– The source of electromagnetic emissions
– The immunity of potential victim systems, and
– The path for EM emissions between the source and victim systems
Victim Susceptible Electrical
or Electronic System
Sourceof
Electromagnetic
Emissions
Pathfor
Electromagnetic
Emissions
47BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Using Reverb Chamber measurement technique (DFS technique) to measure RF shielding of aircraft components (i.e. windows)
refT
refR
refP
PA
,
,
treatmentT
treatmentR
treatmentP
PA
,
,
treatment
ref
treatmentA
ASE log10
Component Shielding
Measurement Applications
48BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Component Shielding
Measurement Applications
49BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
– Open-to-Short reveals useable dynamic range
– Sample-to-Open comparisons reveal sample shielding
– Data from metrology lab room showed good agreement to ideal reverb chamber setup
Component Shielding
Measurement Applications
50BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Component Shielding
– Aircraft Shielding
– Bulk Absorption
– Field Mapping
– Wireless propagation measurements
51BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
–3 distinct types of measurements were made during the aircraft test (all utilizing the DFS measurement technique)
–Reverberant (Reverb) Shielding Measurements
–Direct Illumination Shielding Measurements
–Reverberant (Reverb) Attenuation Measurements
Measurement Applications – Aircraft Shielding
52BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
High Intensity Radiated Fields
(HIRF) Certification Testing:
Greater than 200 meters of
cables
Measurement Applications – Aircraft Shielding
53BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
High power shielding measurement system…
Measurement Applications – Aircraft Shielding
54BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Fiber optic port extenders allowed us to go from…
This… to this!
and still improve on…
Dynamic range
Measurement accuracy/uncertainty
Measurement Applications – Aircraft Shielding
55BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Measurement Applications – Aircraft Shielding
56BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
– Reverb shielding measurements utilize a “nested” chamber approach –paint hanger used as outer chamber, aircraft fuselage considered to be the inner chamber
– Shielding number produced is an average over all incident angles and polarizations
Measurement Applications – Aircraft Shielding
57BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
–Reverb shielding number determined by comparing empty hanger attenuation (or insertion loss) to the “aircraft inserted” attenuation (Tx antenna outside the aircraft, Rx antenna inside the aircraft).
–Hanger insertion loss requires measurement system to have a large dynamic range.
refT
refR
refP
PA
,
,
aircraftT
aircraftR
aircraftP
PA
,
,
aircraft
ref
aircraftA
ASE log10
Measurement Applications – Aircraft Shielding
58BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
–Measurement points…
–2 Tx, 3 Rx points per aircraft area
–Aircraft pressure hull divided into 5 aircraft areas: Main Deck (passenger cabin), Flight Deck, EE Bay, Forward Cargo Bay, and Aft Cargo Bay
Measurement Applications – Aircraft Shielding
59BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Hanger Insertion Loss for empty hanger (REF1) and for hanger with aircraft (REF2)…
Measurement Applications – Aircraft Shielding
60BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Hanger Insertion Loss for empty hanger (REF1) and for hanger with aircraft (REF2)…
Measurement Applications – Aircraft Shielding
61BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Hanger Insertion Loss for empty hanger (REF1) and for hanger with aircraft (REF2)…
Measurement Applications – Aircraft Shielding
62BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
– Directly illuminate device under test with transmit antenna; can be used to directly illuminate apertures of concern
– Can be used to determine a worst case shielding number
Measurement Applications – Aircraft Shielding
63BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
– Measurement of antenna-to-antenna gain / attenuation when both transmit and receive antennas are located inside the device under test
– Provides an indirect assessment of cavity Q and can reveal changes to internal cavity electrical characteristics
Measurement Applications – Aircraft Shielding
64BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Component Shielding
– Aircraft Shielding
– Bulk Absorption
– Field Mapping
– Wireless propagation measurements
65BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
SYNTHETIC
PERSONNEL
USING
DIELECTRIC
SUBSTITUTION
– Using Reverb Chamber measurement technique (DFS technique) to quantify RF absorption characteristics of complex objects
– Engineering problem: Ideally analyze wireless IFE with airplane full of passengers and luggage
– Not feasible for long-term detailed testing
– Looking for alternative to represent loading of the aircraft by passengers
Bulk Absorption
Measurement Applications
66BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
“Dielectric Properties of Vegetables and Fruits as a Function of Temperature, Ash, and
Moisture Content,” O. SIPAHIOGLU AND S.A. BARRINGER, JOURNAL OF
FOOD SCIENCE—Vol. 68, Nr. 1, 2003
ε r for human head
is about 39;
higher for other
tissues (IEEE
1528-2003)
Dielectric Constants
at 2450 MHz
Bulk Absorption
Measurement Applications
67BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Comparing Potatoes to People…
– Starch content is a key parameter for RF Absorption
– Tested 2 types of potatoes: Russets (high starch), Reds (low starch)
Bulk Absorption
Measurement Applications
68BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Low Band
-30
-25
-20
-15
-10
-5
Freq
0.15
94
0.21
94
0.27
94
0.33
94
0.39
94
0.45
94
0.51
94
0.57
94
0.63
94
0.69
94
0.75
94
0.81
94
0.87
94
0.93
94
0.99
94
Freq. (GHz)
dB
Baseline
All ~400 lbs of red & whtpotatoes
150.0 & 155.5 lb. persons
Low Band
-30
-25
-20
-15
-10
-5
0
0.1 0.16 0.22 0.28 0.34 0.4 0.46 0.52 0.58 0.64 0.7 0.76 0.82 0.88 0.94 1
Freq. (GHz)
dB
Foam Chair 150 lb Person in Chair 158.0 lbs of wht
Note: Based on correlation
calculations between
frequency points, we
were likely over-sampling
the chamber below 150
MHz
Potatoes vs. People
100 to 1000 MHz
Bulk Absorption
Measurement Applications
69BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
-45
-40
-35
-30
-25
-20
-15
Freq1.
2
1.40
2
1.60
4
1.80
6
2.00
82.
21
2.41
2
2.61
4
2.81
6
3.01
83.
22
3.42
2
3.62
4
3.82
6
4.02
84.
23
4.43
2
4.63
4
4.83
6
5.03
85.
24
5.44
2
5.64
4
5.84
6
Freq. (GHz)
dB
Baseline
208.5 wht
200.5 lb red
All 400 lb. red & wht
150.0 & 155.5 lb Persons
-45
-40
-35
-30
-25
-20
-15
Freq1.
2
1.40
2
1.60
4
1.80
6
2.00
82.
21
2.41
2
2.61
4
2.81
6
3.01
83.
22
3.42
2
3.62
4
3.82
6
4.02
84.
23
4.43
2
4.63
4
4.83
6
5.03
85.
24
5.44
2
5.64
4
5.84
6
Freq (GHz)
dB
Foam Chair
150 lb personon chair
158.0 lbs of wht
Potatoes vs. People
1 to 6 GHz
Bulk Absorption
Measurement Applications
70BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Bulk Absorption
Measurement Applications
72BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Bulk Absorption
– Component Shielding
– Aircraft Shielding
– Field Mapping
– Wireless propagation measurements
73BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Measurement of antenna-to-antenna coupling when both transmit and receive antennas are located inside the test article (aircraft, in our case)
Provides an indirect assessment of cavity Q and can reveal changes to internal cavity electrical characteristics
Similar measurements can be used to provide wireless channel characterization
Cavity Field Mapping
Measurement Applications
74BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Rx
Results from cavity field mapping…
Cavity Field Mapping
Measurement Applications
75BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
More results from inside a large passenger cabin…
Cavity Field Mapping
Measurement Applications
76BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Agenda
Reverberation Chambers
– Overview
– Discrete Frequency Stirring
Metrology Application of Reverberation Chambers
– Probe Calibration
– Antenna Efficiency
Measurement Applications
– Bulk Absorption
– Component Shielding
– Aircraft Shielding
– Field Mapping
– Wireless propagation measurements
77BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Deliver DVD quality streamed unicast video to every seat
Airplane is high multipath environment, but with curved boundary surfaces, how correlated will multipath be?
Need Coverage, Delay Spread, Angle of Arrival / Departure statistics to build a good Airplane MIMO channel model
– Optimize installation locations
– Optimize antennas types, orientations, spacing
– Optimize radio designs
46
47
48
49
50
51
52
53
54
55
56
57
58
45
46
47
48
49
50
51
52
53
54
55
56
45
46
47
48
49
50
51
52
53
54 55
56
57
57
20
21
22
23
24
25
26
27
28
29
30
31
32
21
22
23
24
25
26
27
28
29
30
31
21
22
23
24
25
26
27
28
29
30
31
7 8 9 10
11
12
13
14
15
7 8 9 10
11
12
13
14
15
7 8 9 10
11
12
13
14
151
G
3G
3K
3A
2C
2D
2H1
K1
A
Conceptual coverage layout, 777-300
Wireless propagation measurements
Measurement Applications
78BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Channel Sounding
Translation Stages
Wireless propagation measurements
Measurement Applications
79BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Energy across X-Z grid Energy vs. Polar Direction
Energy/Angle vs. Time
Wireless propagation measurements
Measurement Applications
80BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Wireless propagation measurements
Measurement Applications
81BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
26
27
28
29
30
31
32
23
25
24
45
46
47
48
49
50
51
52
53
54
55
56
23
24
25
26
27
28
29
30
31
32
45
46
47
48
49
50
51
52
53
54
55
56
57
57 58 59
45
46
47
48
49
50
51
52
53
54
55
56
58
59
58
59
5726
27
28
29
30
31
32
23
25
24
60
60
6 3
5
4
6
3 5
4
TX 2
PN
A
TX 1
9
7
5,
6 1
3
2
1
2 1
1 4 5 62 3
PNA
211
Angle of Arrival over Time (Seq017)
Time (sec)
Ang
le (d
eg)
0 0.5 1 1.5 2 2.5 3
x 10-7
-150
-100
-50
0
50
100
150
Example Angle Spectrum
DC-10 Seat 51E
Wireless propagation measurements
Measurement Applications
82BOEING is a trademark of Boeing Management Company.
Copyright © 2009 Boeing. All rights reserved.
Summary
Reverberation chambers can be used to calibrate field probes with comparable uncertainties to Anechoic chambers
Frequency, Spatial and Mode averaging reduce Field uniformity to level sufficient to measure antenna efficiency.
Probe calibrations in reverberation chamber appear to be more repeatable than anechoic chamber method.
Discreet Frequency Stirring reduces test times and is well suited for stirring aircraft
Nested chambers approach is useful for characterizing odd shaped objects
Statistical methods used in the lab can be utilized for evaluation of EM environment onboard aircraft