KOLEJ UNIVERSITI TEKNOLOGI TUN HUSSEIN ONN
BORANG PENGESAHAN STATUS TESIS·
JUDUL:
Saya
CHARACTERIZA TION OF ELECTRIC FIELD DISTRIBUTION IN A GTEM CELL
SESI PENGA.IIAN: 2003/2004
AIZAN BIN UBIN
(HURUF BESAR)
mcngaku mcmbcnarkan tcsis (Sarjana-MUElafSarjana /&elaer-Falsafilh)* ini disimpan di Pcrpustakaan dcngan syarat-syarat kcgunaan scpcrti bcrikut:
I. Tcsis adalah hakmilik Kolcj Univcrsiti Tcknologi Tun Husscin ann. 2. Pcrpustakaan dibcnarkan mcmbuat salinan untuk tujuan pcngajian sahaja. 3. Pcrpustakaan dibcnarkan mcmbuat salinan tcsis ini scbagai bahan pcrtukamn antam institusi
pcngajian tinggi.
4. **Sila tandakan (" )
o o ~
SULIT
TERHAD
(Mcngandungi maklumat yang bcrdarjah kcsclamatan atau kcpcntingan Malaysia scpcrti yang tcmlaktub di dalalll AKTA RAHSIA RASMI1972)
(Mcngandungi Illaklulllat TERHAD yang tclah ditcntukan olch organisasilbadan di mana pcnyclidikan dijalankan)
TIDAK TERHAD
Disahkan olch:
(TANDATANGAN PENULlS)
Alamat Tctap:
17 .IALAN TIONG 3, 83500 PARIT SULONG, BATU PAHAT, .I0HOR.
PROF. DR. l\IOHD ZARAR BIN l\IOHD .IENU ( Nama Pcnyclia )
Tarikh: __ 2_7_A_I_'R_I_L_20_0_4 __ _ Tarikh: 27 APRIL 2004
CATATAN: * **
•
Po tong yang tidak bcrkcnaan. Jika tcsis ini SULIT at au TERHAD, sila lalllpirkan sura! daripada pihak bcrkuasa/organisasi bcrkcnaan dcngan mcnyatakan sckali tcmpoh tcsis ini perlu dikclaskan scbagai SULIT atau TERHAD. Tcsis dimaksudkan scbagai tcsis bagi Ijazah Doktor Falsafah dan Sarjana sccara pcnyclidikan. atau discrtasi bagi pcngajian sccam kcrja kursus dan pcnyclidikan. at au Laporan Projck Sarjana ivluda (PS;\I).
"I hereby acknowledge that the scope and quality of this thesis is qualified for the
award of the Master Degree of Electrical Engineering"
Signature
Name PROF. DR. MOHD ZARAR BIN MOHD JENU
Date 27 APRIL 2004
CHARACTERIZATION OF ELECTRIC FIELD
DISTRIBUTION IN A GTEM CELL
AIZAN BIN UBIN
A project report is submitted as partial fulfillment of the requirements for the award
of the Master Degree of Electrical Engineering
Department of Electrical Enginecring
Faculty of Enginccring
Ko\cj Univcrsiti Tcknologi Tun Husscin Onn
APRIL. 2004
11
"All the trademark and copyrights use herein are property of their respective owner.
References of infonnation from other sources are quoted accordingly; otherwise the
information presented in this report is solely work of the author."
Signature
Author AIZAN BIN UBIN
Date 27 APRlL 2004
Par 11Iy 'Wife 1(fiairaty CJ3inti CJ3acfrol1,
:My SOIlS,
:Mu fia 111 111 a a Parfial1 ana :Mufiammaa Zaf(]vall,
:My aaugfitel~
jl11lirafi Parzana.
111
IV
ACKNOWLEDGEMENT
The author wishes to extend his sincere appreciation to the project supervisor
Professor Dr Mohd Zarar Bin Mohd Jenu for his guidance, help and advice
throughout this project.
The author wishes to express his thanks to Mr. Azwan, Shahrul, Mohd
Shamian, Nazri, Xavier, Erdi and others whose name could not be mentioned here
one by one. Your encouragement and concem is greatly appreciated by author.
In particular, my most appreciation is for my wife and family members for
their support during this project.
The author wishes to thank everyone who has helped in one way or another
towards the successful implementation of this project.
Finally, I would like to praise and thank God for giving me patience,
perseverance and strength to complete this project.
\'
ABSTRACT
Two of the most important measurements related to electromagnetic
compatibility (EMC) are radiated emission and radiated immunity. These measurements
must be performed in a facility which provides reliability and reproducibility. The
Gigahertz Transverse Electromagnetic Mode (GTEM) cell is one of the facilities for
EMC measurement due to its well defined electric and magnetic field distribution in
addition to being cost effective. The research undertaken in this project is to determine
the field distribution in the GTEM by using Finite Difference Time Domain (FDTD).
The results from the modeling are then compared with actual measurements and any
differences will be noted and explained. The field strength inside a GTEM cell is a
fl.lI1ction of the input power as well as location along the longitudinal axis or septum
height. Radiated immunity measurements require field uniformity (+6 dB according to
IEC 61000-4-3 standard) which depends on the design aspects of the GTEM such as
size, material and absorbing condition. The capability of the GTEM cell to provide the
unifo1111 field can be tested theoretically and experimentally. FDTD is a numerical
method that can be used to predict the electric field distribution in a GTEM cell. The
electric field distribution for frequencies at 100 MHz, 200 MHz, and 400 MHz were
calculated using the EZ-FDTD software. In this report, theoretical study on the field
strength and distribution in a GTEM cell is described. It is followed by making
measurements of the field based on the radiated immunity test setup. It is found that at
septum height 63 cm for frequency 100 MHz, the measured and simulated results are
very close. This is the location recommended by the manufacturer for the placement of
equipment under test (EUT) in radiated emission and radiated immunity test. The
difference varies from 0.01 dB to 4.91 dB. The difference between modeling and actual
measurement can be attributed to the input field distribution, inhomogeneous
characteristics of the septum and existence of standing wave. In the future, it is
recommended that other numerical methods such as Finite Element Method (FEM) and
Transmission Lines Method (TLM) be used and more accurate model and absorbing
boundary condition parameters be implemented.
VI
ABSTRAK
Dua daripada pengukuran paling penting berhubung keserasian elektromagnet
(EMC) adalah panearan radiasi dan ketahanan radiasi. Pengukuran ini mestilah
dilakukan di dalam kemudahan yang menyediakan kebolehharapan dan
kebolehulangan. Sel Mod Elektromagnet Melintang Gigahertz (GTEM) adalah satu
daripada kemudahan untuk pengukuran EMC hasil daripada medan elektrik dan
medan magnetnya yang tertakrif dengan baik disamping kosnya yang efektif.
Penyelidikan yang dijalankan di dalam projek ini adalah untuk menentukan taburan
medan di dalam GTEM menggunakan Bezaan Terhingga Domain Masa (FDTD).
Keputusan daripada permodelan kemudian dibandingkan dengan pengukuran sebenar
dan sebarang perbezaan diantaranya akan dieatat dan dihuraikan. Kekuatan medan di
dalam sel GTEM adalah fungsi bagi kuasa masukan dan juga lokasi sepanjang paksi
membujur atau ketinggian septum (pengalir dalam). Pengukuran ketahanan radiasi
memerlukan keseragaman medan (+ 6 dB menurut piawaian IEC 61000-4-3) yang
bersandar kepada aspek rekabentuk sel GTEM seperti saiz, bahan dan keadaan
serapan. Kemampuan sel GTEM menyediakan medan yang seragam boleh diuji
seeara teori dan ujikaji. FDTD adalah satu kaedah berangka yang boleh digunakan
untuk meramal taburan medan elektrik di dalam sel GTEM. Taburan medan elektrik
pada frekuensi 100 MHz, 200 MHz dan 400 MHz telah dikira menggunakan perisian
EZ-FDTD. Di dalam laporan ini, kajian teori ke atas kekuatan medan dan taburannya
di dalam sel GTEM diterangkan. Ianya diikuti dengan melakukan penguh.'uran medan
berdasarkan pengujian ketahanan radiasi. Didapati bahawa pada ketinggian septum
63 em untuk frekuensi 100 MHz, keputusan pengukuran dan simulasi adalah paling
hampir. Lokasi ini adalah yang dieadangkan oleh pengeluar untuk perletakan
peralatan dibawah ujian (EUT) dalam ujian panearan radiasi dan ketahanan radiasi.
Perbezaan berubah dari 0.01 dB hingga 4.91 dB. Perbezaan diantara permodelan dan
pengukuran sebenar boleh disifatkan kepada masukan taburan medan, eiri-eiri
ketakhomogenan bagi septum dan kewujudan gelombang pegun. Di masa hadapan,
adalah dieadangkan kaedah berangka yang lain seperti Kaedah Elemen Terhingga
(FEM) dan Kaedah Penghantaran Talian (TLM) digunakan dan model dan
parameter keadaan serapan sempadan yang lebih tepat dilaksanakan.
CHAPTER
CHAPTER I
TABLE OF CONTENTS
TITLE
DECLARA TION
DEDICATION
ACKNOWLEDGEi\IENT
ABSTRACT
ABSTRAK
TABLE OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
GLOSSARY OF ABBREVI:\ TIONS
LIST OF SYi\1BOLS
LIST OF APPENDICES
INTRODUCTION
1.1 Introduction to Project
1.2
1.3
IA
Objecti\'es
Scopes or Work
Importancc or Projcct
\ II
PACE
i\U:\IBER
II
III
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V III
CHAPTER II LITERA TURE REVIEW 4
2.1 Introduction 4
2.2 EMC Measurement Facilities 5
2.2.1 Open Area Test Site (OATS) 5
2.2.2 Anechoic Room 6
2.2.3 TEM Cell 6
2.2.4 GTEM Cell 7
2.3 Radiated Immunity Overview 8
2.4 GTEM Cell Concept 8
2.4.1 Testing Volume 9
2.5 GTEM Parameters 9
2.5.1 Characteristic Impedance 10
2.5.2 Unifonnity of Electric Field 10
2.6 Electric Field Strength 11
2.7 GTEM Tem1ination 13
2.7.1 Current Tem1ination 13
2.7.2 Field Termination 14
2.8 Wave Propagation 15
2.9 Finite Difference Time Domain Method 16
2.9.1 Basic FDTD and
Maxwell's Equations 17
2.9.1.1 One Dimensional FDTD 17
2.9.1.2 Two Dimensional FDTD 18
2.9.1.3 Three Dimensional FDTD 20
2.10 Stability Condition 24
2.11 Boundary Condition 25
2.12 Electric Field Distribution Work 28
CHAPTER III
CHAPTER IV
CHAPTER V
METHODOLOGY
3.1
3.2
3.3
3.4
Introduction
FDTD GTEM Model
Measurement Procedure
Radiated Immunity Measurement System
SIMULA TION MODEL AND MEASUREMENTS
4.1 Model Definition
4.2 Computational Domain
4.3 Absorbing Boundary Condition
4.4 Plate
4.5 Source Parameter
4.6 Monitor Point (Observation Points)
4.7 Lumped Element
4.8 Instrumentation for Measurement
4.8.1 Electric Field Probe
4.8.2 Directional Coupler
4.8.3 Signal Generator
4.8.4 Power Amplifier
4.8.5 Control Software
RESULTS AND ANALYSIS
5.1
5.2
5.3
Introduction
Result
Analysis
IX
29
29
29
31
32
34
34
34
35
36
37
37
38
38
39
40
41
41
42
43
43
44
46
x
CHAPTER VI CONCLUSIONS AND RECOMMENDATIONS 51
REFERENCES
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D
APPENDIX E
6.1 Conclusion
6.2 Recommendations for Future Work
51
52
53
56
61
66
76
78
\\
LIST OF TABLES
TABLE NO. TITLE PAGE
5.1 The cutoff frequencies for higher modes related to
cross sectional dimension ofGTEM cell 47
5.2 The cOITelation coefficients of the measured
electric field to calculated electric field 49
5.3 The minimum and maximum ratio of the measured
electric field to calculated electric field 50
Xli
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 EMC Structure 5
2.2 Typical TEM cell 7
2.3 Diagram of GTEM cell 9
2.4 Field strength at the testing volume II
2.5 The electric field strength related to the height of septum
for different values of power with characteristic
line impedance son 12
2.6 The broadband pyramidal RF absorbers 14
2.7 TEM waves IS
2.8 One Dimensional FDTD Grid 18
2.9 Two Dimensional FDTD Grid 19
2.10 Three dimensional FDTD grid (Yee cell) 23
2.11 Reflectionless transmission of a plane wave at PML
and free space interface 27
3.1 Typical Setup for RF Immunity 32
3.2 Methodology Flowchart 33
4.1 FDTD GTEM Model 36
4.2 Schaffner GTEM 750 38
4.3 The Side View of GTEM Cell 39
4.4 The Top View of GTEM Cell 39
4.5 HI-4422 Electric field probe 40
4.6 Dual directional coupler 41
X 111
5.1 The measured and calculated of electric field distribution
below septum height, h = 63cm for 100 MHz. 44
5.2 The measured and calculated of electric field distribution
below septum height, h = 63cm for 200 MHz 45
5.3 The measured and calculated of electric field distribution
below septum height, h = 63cm for 400 MHz 45
5.4 The electric field strength at 100 MHz at y = 20 cm
from the floor of outer conductor. a) Septum height 54 cm
b) Septum height 63 cm c) Septum height 70 cm 48
ABC
CW
DC
EMC
EMI
EMS
EUT
FDTD
FEM
GPIB
GTEM
OATS
PEC
PML
RAM
RF
TEM
TUvl
GLOSSARY OF ABBREVIA nONS
Absorbing Boundary Conditions
Continuous Wave
Direct Current
Electromagnetic Compatibility
Electromagnetic Interference
Electromagnetic Susceptibility
Equipment Under Test
Finite Difference Time Domain
Finite Element Method
General Purpose Interface Bus
Gigahertz Transverse Electromagnetic Mode
Open Area Test Site
Perfect Electric Conductor
Perfectly Matched Layer
Radio Frequency Absorbing Material
Radio Frequency
Transverse Electromagnetic Mode
Transmission Lines fvlcthod
XI\'
B
C
c
D
E
J H
h
J
n
P
P"
v
Voutcr
v
Z
b.(
b..x,b.y,b.z
LIST OF SYMBOLS
Magnetic flux density (T or Wb/m2)
Capacitance (F)
Speed of light in free space (m/s)
Electric flux density (C/nl)
Electric field strength (Vim)
Frequency (Hz)
Magnetic field strength (Aim)
Distance between center conductor and
outer floor conductor (m)
Current density (Alm 2)
Number of step
Input power (W)
Volume charge density (C/m3)
Time (s)
Input voltage (V)
Voltage at center conductor (V)
Voltage at outer conductor (V)
Phase velocity (m/s)
Characteristic impedance (Q)
Time step (s)
Space increment or cell size (m)
Conductivity of material (S/m)
Pem1ittivity of free space (F/m)
Pem1ittivity of material (F/m)
xv
f.1
['
'7
A
Permeability of material (Him)
Amount of reflection
Intrinsic impedance (n)
Wavelength (01)
XVI
LIST OF APPENDICES
APPENDIX NO. TITLE
A
B
C
D
E
GTEM EZ-FDTD Model and Model Definition Tab
Electric Field Distribution
Simulation and Measurement Data
Sample MA TLAB Code for Graph Plotting
Observation Points
xvii
PAGE
56
61
66
76
78
CHAPTER I
INTRODUCTION
1.1 Introduction to Project
The measurement method for radiated emission and radiated susceptibility
requires a method, which is reliable and reproducible. This is important to ensure the
measurements fl.dfill the electromagnetic compatibility (EMC) standard. The
Gigahertz Transverse Electromagnetic Mode (GTEM) cell as a new measurement
facility in electromagnetic compatibility need to be evaluated especially its electric
field distributions.
It is important to determine the field strength and distribution in a GTEM cell
for EMC and calibration measurements. The field strength inside a GTEM Cell is a
function of the input power as well as location along the longitudinal axis or septum
height. Immunity measurements require field uniformity (+6 dB according to IEC
61000-4-3 standard) over certain test area and calibration can only be carried out if
the precise field strength at a particular location is known.
2
Finite Difference Time Domain (FDTD) is a numerical method that can be
used to predict the electric field distribution in a GTEM cell. FDTD is a tool to
calculate the electric field in a defined test volume in a GTEM cell. The electric field
distribution at certain frequency was calculated using EZ-FDTD software based on
FDTD method.
In this report, theoretical study on the field strength and distribution in a
GTEM cell is described. It is followed by making measurements of the field. The
results from both works will be compared and the differences will be noted and
explained. The differences of the theoretical and measurements denotes the sources
of field problems and recommended solution will be mentioned.
1.2 Objectives
i) To perfonTI numerical modeling of field strength in GTEM cell using
Finite Difference Time Domain, (FDTD).
ii) To conduct measurements of field strength in GTEM cell based on
immunity measurement setllp.
iii) To analyze, compare, and conclude the results obtained from the
modeling and measurements.
1.3 Scopes of Work
i) Measurement and calculation of electric field distribution was done at
frequency 100MHz, 200M Hz and 400MHz.
ii) Simulation model using three-dimensional FDTD method.
iii) Measurement GTEM facility is GTEM 750 model by Schaffner.
iv) Electric field distribution for an unloaded GTEM cell.
v) Measurement and calculation was done at three different planes where
septum height, h was 54cm, 63cm, and 70cm.
1.4 Importance of Project
i) To determine the capability of a GTEM cell as a measurement facility in
electromagnetic compatibility.
ii) To provide an input to GTEM manufacturer to improve their GTEM cell.
3