DESIGN OF MODIFIED MICROWAVE POWER DIVIDER FOR RADAR

ELECTRONIC WARFARE TRANSCEIVING SYSTEM

AMIR RUDIN BIN MAT DIN

A project report submitted in partial fulfillment of the requirement for the award of

the degree of Master of Engineering (Electrical-Electronic and Telecommunication)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

APRIL 2007

iii

Special dedicated to my beloved parents and friends

for their support and encouragement.

iv

ACKNOWLEDGEMENT

First and foremost, I would like to take this opportunity to thank all the

important people who were responsible in making this project a success, may it be

directly or indirectly involved. Thank you for making this thesis a reality.

My special appreciation to my supervisor, Associate Professor Dr Mazlina

Esa who had coached and guided me in every possible way to ensure this project is a

success. My special thanks to all my course mates.

I would also like to thank my Commanding Officers, Chief of EW Wing for

their support and assistance in making this project a success. Last but not least,

special thank to the Chief of Signals Officer for giving me the support and

opportunity to future my studies.

v

ABSTRACT

Radar electronic warfare beam forming transceiving system requires robust

components in order to fully utilize the radar functionality. One such essential

component is the power divider and its complementary power combining circuitry.

Conventional power divider operates at a fundamental frequency and odd harmonics.

The thesis presents the design of a broadband modified 2-way microwave power

divider with the capability of delivering an identical signal as the backup to a radar

electronic warfare transceiving system. The chosen band of the radar system is from

0.7 GHz to 3 GHz. The design starts with the basic conventional 2-way Wilkinson

power divider. Modifications were done in the form of having trisection transmission

lines and integrate it with either single or combination of lumped element loads of

resistor, capacitor and inductor. The component values were initially computed.

Investigations on the configurations were performed using an electromagnetic

simulation software. It can be concluded that an optimum broadband modified power

divider has been successfully designed to operate between 0.7 GHz to 3 GHz with

equal power division of -3 dB at each output port.

vi

ABSTRAK

Sistem pemancar-penerima radar peperangan elektronik membentuk alur

memerlukan komponen tahan lasak bagi memenuhi keperluan operasi radar. Satu

komponen asas penting ialah litar pembahagi dan penggabung kuasa. Pembahagi

kuasa lazim beroperasi pada frekuensi asas dan harmonik ganjil. Tesis ini

membentangkan rekabentuk pembahagi kuasa gelombang mikro jalurluas dengan

keupayaan menghasilkan isyarat serbasama sebagai isyarat kedua bagi sistem

pemancar-penerima radar peperangan elektronik. Jalur operasi sistem radar ini

dipilih bagi julat 0.7 GHz sehingga 3 GHz. Penyelidikan ke atas Rekabentuk litar

dimulai dengan litar asas pembahagi kuasa 2-hala. Seterusnya, ubahsuaian dibuat

terhadap litar dalam bentuk talian penghantaran tiga bahagian. Ini kemudiannya

diintegrasi dengan beban tergumpal perintang, kapasitor dan induktor, tunggal atau

gabungan. Nilai komponen dikira terlebih dahulu. Kajian menyeluruh terhadap

prestasi rekabentuk dibuat menggunakan perisian simulasi elektromagnet. Dapat

disimpulkan bahawa pembahagi kuasa yang optimum telah berjaya direka untuk

berkendali antara 0.7 GHz dan 3 GHz. Ia mempunyai ciri pembahagian kuasa yang

sama sebesar -3 dB pada setiap port keluaran.

vii

TABLE OF CONTENTS

TITLE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES ix

LIST OF FIGURES x

LIST OF SYMBOLS xiii

LIST OF ABBREVIATIONS xiv

LIST OF APPENDICES xv

CHAPTER TITLE PAGE

1 INTRODUCTION

1.1 Background of the Project 2

1.2 Objective of the Project 3

1.3 Problem Statement 3

1.4 Scopes of Project 4

1.5 Organization of Thesis 6

viii

2 FUNDAMENTALS OF POWER DIVIDERS

2.1 Introduction 7

2.2 Microstrip Technology 8

2.3 Basic Properties of Power Divider 10

2.4 Wilkinson Power Divider 13

2.4.1 Introduction 13

2.4.2 Brief Basic Theory 14

2.5 Design of Modified Wilkinson Power Divider 17

2.6 Design Methodology 22

3 SOFTWARE USED

3.1 AWR Microwave Office 24

4 RESLUTS AND DISCUSSIONS

4.1 Basic Conventional Wilkinson Power Divider 27

4.2 Tri Section Modified Wilkinson Power Divider with

Lumped Element 34

4.3 Tri Section Modified Wilkinson Power Divider with

R Segment in Cascade 45

4.4 Improving the Modified Wilkinson Power Divider 53

4.5 Summary 56

5 CONCLUSIONS AND RECOMMANDATIONS

5.1 Conclusion 57

5.2 Suggestions for Further Research 58

REFERENCES 59

APPENDIX 62

ix

LIST OF TABLES

TABLE NO. TITLE PAGE

4.1 Prototype values for conventional design. 27

4.2 Simulated data reading for conventional WPD. 33

4.3 Simulated results with varying L. 39

4.4 Simulated results with varying C. 42

4.5 Simulated results with varying L and C. 45

4.6 Performance comparisons between all WPD configurations. 56

x

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 Antenna sectors of the ELINT System. 2

1.2 Land Mobile ELINT System. 2

1.3 Conventional 2-way WPD. 5

1.4 Dual-band WPD with open stub. 5

1.5 2 Way WPD with RLC. 6

2.1 Power division. 8

2.2 Cross sectional view of a microstrip line. 8

2.3 Electric field and magnetic field line in microstrip line. 9

2.4 Power divider developed by Wilkinson. 13

2.5 Schematic diagram of a Wilkinson power divider. 14

2.6 Symmetrical circuit for the even-odd mode analysis ofWilkinson network

15

2.7 Simplified equivalent circuit for the even mode analysis. 15

2.8 Simplified equivalent circuit for the odd mode analysis. 16

2.9 Simplified equivalent circuit of the Wilkinson power divider. 16

2.10 Wilkinson power divider based on the transmission linetransformer structure.

18

2.11 Layout of a Tri Section Wilkinson Power Divider. 20

2.12 Simulated return losses responses of a Tri Section WPD. 21

2.13 Simulated isolation responses of a Tri Section WPD. 21

2.14 Simulated coupling responses of a Tri Section WPD. 22

2.15 Design Methodology. 23

3.1 An Example of AWR Microwave Office sheet. 25

xi

4.1 Basic Conventional WPD Circuit. 28

4.2 Simulated return loss of basic WPD at 0.9 GHz. 28

4.3 Simulated isolation of basic WPD at 0.9 GHz. 29

4.4 Simulated power division of basic WPD at 0.9 GHz. 29

4.5 Simulated return loss of basic WPD at 1.8 GHz. 30

4.6 Simulated isolation of basic WPD at 1.8 GHz. 30

4.7 Simulated power division of basic WPD at 1.8 GHz. 31

4.8 Simulated return loss of basic WPD at 2.7 GHz. 31

4.9 Simulated isolation of basic WPD at 2.7 GHz. 32

4.10 Simulated power division of basic WPD at 2.7 GHz. 32

4.11 The schematic layout for basic Tri Section ModifiedWPD.

34

4.12 Simulated return loss of basic Tri Section ModifiedWPD.

35

4.13 Simulated isolation of basic Tri Section Modified WPD. 35

4.14 Simulated power division of basic Tri Section ModifiedWPD.

36

4.15 The schematic layout for Tri Section Modified WPDwith RL Element.

37

4.16 Simulated return loss of Tri Section Modified WPDwith RL Element.

37

4.17 Simulated isolation of Tri Section Modified WPD withRL Element.

38

4.18 Simulated coupling or power division of Tri SectionModified WPD with RL Element.

38

4.19 The schematic layout for Tri Section Modified WPDwith RC Element.

40

4.20 Simulated return loss of Tri Section Modified WPDwith RC Element.

40

4.21 Simulated isolation of Tri Section Modified WPD withRC Element.

41

4.22 Simulated coupling or power division of Tri SectionModified WPD with RC Element.

41

4.23 The schematic layout for Tri Section Modified WPDwith RLC Element.

43

xii

4.24 Simulated return loss of Tri Section Modified WPDwith RLC Element.

43

4.25 Simulated isolation of Tri Section Modified WPD withRLC Element.

44

4.26 Simulated coupling or power division of Tri SectionModified WPD with RLC Element.

44

4.27 The schematic layout for Tri Section Modified WPDwith 2nd Segment in Cascade.

46

4.28 Simulated return loss of Tri Section Modified WPDwith 2nd Segment in Cascade.

46

4.29 Simulated isolation of Tri Section Modified WPD with2nd Segment in Cascade.

47

4.30 Simulated power division of Tri Section Modified WPDwith 2nd Segment in Cascade.

47

4.31 The schematic layout for Tri Section Modified WPDwith 1st Segment in Cascade.

48

4.32 Simulated return loss of Tri Section Modified WPDwith 1st Segment in Cascade.

49

4.33 Simulated isolation of Tri Section Modified WPD with1st Segment in Cascade.

49

4.34 Simulated power division of Tri Section Modified WPDwith 1st Segment in Cascade.

50

4.35 The schematic layout for Tri Section Modified WPDwith Full Segment in Cascade.

51

4.36 Simulated return loss of Tri Section Modified WPDwith Full Segment in Cascade.

51

4.37 Simulated isolation of Tri Section Modified WPD withFull Segment in Cascade.

52

4.38 Simulated power division of Tri Section Modified WPDwith Full Segment in Cascade.

52

4.39 The schematic layout for Final Design of Tri SectionModified WPD with Full Segment in Cascade.

54

4.40 Simulated return loss for Final Design of Tri SectionModified WPD with Full Segment in Cascade.

54

4.41 Simulated isolation for Final Design of Tri SectionModified WPD with Full Segment in Cascade.

55

4.42 Simulated power division for Final Design of TriSection Modified WPD with Full Segment in Cascade.

55

xiii

LIST OF SYMBOLS

h - Thickness of Substrate

r - Relative Permittivity

εe - Effective Permittivity

vp - Phase Velocity

α - Attenuation Constant

β - Phase Constant

t - Thickness of Conductor

R - Resistance

G - Conductance

L - Inductance

C - Capacitance

Z0 - Characteristic Impedance

ZL - Load Impedance

Γ - Reflection Coefficient

xiv

LIST OF ABBREVIATIONS

EW Electronic Warfare

ELINT Electronic Intelligence

WPD Wilkinson Power Divider

MWO Microwave Office

EM Electromagnetic

BW Bandwidth

xv

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Simulation Result for Tri Section Modified WPD 62

1

CHAPTER I

INTRODUCTION

1.1 Background of the Project

Power combiners and dividers are passive devices. These are needed in

microwave systems for combining power of signals from several inputs and

distributing the power of an input signal into several outputs, respectively. The

combination can be at the front end, whereby it may be too laborious to design a high

power amplifier. Instead, each output of the power divider can then be amplified, and

all the amplified signals were then recombined. This will result in a highly amplified

signal, with the amplification done using low power amplifiers.

One radar system being studied in this project is the Electronic Intelligence

System or ELINT station [1]. It is a passive radar, functioning as a non-

communication system. Its current operating capability is from 0.7 GHz to 18 GHz,

with four antenna sectors, as illustrated in Figure 1.1. The bandwidth of the sectors is

0.7 GHz to 3 GHz, 3 GHz to 8 GHz and 8 GHz to 18 GHz, respectively. The 4th

sector is a dummy and can be upgraded.

The power divider is proposed to provide a back-up for the incoming signals.

The station is part of an electronic warfare system available. A 2-way microwave

power divider will ensures two identical signals of half the input signal be delivered

2

from the inception to the receiving circuitry. One signal will remain in operation. The

second identical signal serves as the backup to the ELINT system. Wilkinson Power

Divider (WPD) has been identified as the suitable configuration due to its simple

circuitry. It also has excellent characteristics of excellent impedance matched at all

ports, lossless, good isolation, compact, and can easily be fabricated using cost

effective readily available materials. The narrowband property can be improved for

broadband characteristics. The land mobile ELINT system is shown in Figure 1.2.

Figure 1.1 Antenna sectors of the ELINT System [1].

Figure 1.2 Land Mobile ELINT System [1].

3

1.2 Objective of the Project

The objective of this project is to design a modified power divider with the

capability of delivering an identical signal as the backup to a radar electronic warfare

transceiving system. It has to exhibit broadband characteristic within 0.7 GHz to 3

GHz. The bandwidth was chosen as it is the smallest range available.

1.3 Problem Statement

In recent years, the microwave technology has undergone tremendous

development. One of such development is the Radar and Electronic Intelligence

system known as the ELINT system. The ELINT system is a very expensive set-up in

electronic warfare area. It is also a complex system. However, there is a limitation

with regards to measurement and sampling aspects, due to the quality of the receiving

signal. There is a crucial need for a backup system in the usage to enhance its

capabilities. Hence, the proposed backup system in the form of a robust broadband

microwave power divider can be used for monitoring and surveillance purposes.

Accurate data can then be determined based on the quality of the pickup or received

signal. The quality of the receiving signal can be significantly improved.

4

1.4 Scopes of Project

The scopes of the project are as follows:

(i) design of single basic WPDs, each operating at 0.9 GHz, 1.8 GHz and

2.7 GHz. These single frequencies will form the three initial main

operating frequencies in the desired broadband region. Simulate [2]

and investigate the possibility of improving the circuit characteristics.

Simulations were done using electromagnetic simulation software,

AWR Microwave Office 2004.

(ii) modification of the conventional WPD configuration into tri-sections

of transmission lines to reflect the three identified main operating

frequencies. Simulations are performed and the performances

investigated.

(iii) further modifications using lumped element loadings.

(iv) fine-tune for optimum configuration which fulfill desired

specifications.

The desired design specifications are as follows:

(i) broadband operating frequencies : 0.7 GHz to 3 GHz

(ii) 3 dB coupling or half-power division : between ports 1 and 2,

and ports 1 and 3

(iii) good isolation of < -10 dB : between ports 2 and 3

(iv) good return loss of < -10 dB : at ports 1, 2 and 3

The chosen microwave board has the following parameters:

(i) PTFE microwave board : RO4003 (Rogers)

(ii) thickness of substrate , h : 0.81 mm

(iii) relative permittivity of substrate, r : 3.38

(iv) loss tangent of substrate, tan : 0.0027

(v) thickness of conductor, t : 35 µm

5

The basic single operation conventional WPD is shown in Figure 1.2 [3]. Two

configurations available in the literature are used as the main references for this

project [4], [5]. The corresponding circuits are shown in Figures 1.3 and 1.4,

respectively.

Figure 1.3 Conventional 2-way WPD [3].

Figure 1.4 Dual-band WPD with open stub [4].

6

Figure 1.5 2 Way WPD with RLC [5].

1.5 Organization of Thesis

This thesis consists of five chapters. Chapter I present the objectives of the

project, the problem statement, project background, the scope of project, and lastly

the organization of this thesis.

Chapter II discusses the Power Divider theory, discussion include scattering

parameter, odd and even analysis for Wilkinson Power Divider and its response,

characteristic and design methodology.

Chapter III discusses on the software used in the design, mainly AWR

Microwave Office 2004.

Chapter IV presents the results and discussions were made.

Chapter V concludes the thesis and suggestions for future work were made.

59

REFERENCES

[1] Users Manual - Land Semi-Mobile ELINT System, Sysdel. CC. BK, South

Africa, 1985.

[2] Applied Wave Research Institute, MWO/VSS Getting Started Guide v6.5,

Applied Wave Research, Inc, 2004.

[3] David M. Pozar, Microwave and RF Wireless System, USA: Wiley, 2001.

[4] Kun-Hui Yi and Bongkoo Kang, Modified Wilkinson Power Divider for nth

Harmonic Suppression, IEEE Microwave and Wireless Components Letters,

Vol. 13, No. 5, May 2003.

[5] Lei Wu, A Dual-Frequency Wilkinson Power Divider, IEEE Transactions

On Microwave Theory And Techniques, Vol. 54, No. 1, January 2006.

[6] I. Kneppo, J. Fabian, Microwave Integrated Circuits, London: Chapman,

1994.

[7] K. Chang, L. Hsieh, Microwave Ring Circuits and Related Structures, USA:

Wiley, 2004.

[8] E. J. Wilkinson, An N-Way Hybrid Power Divider, IRE Transactions on

Microwave Theory and Techniques, January 1960.

[9] Mitchai Chongcheawchamnan, Tri-Band Wilkinson Power Divider Using a

Three-Section Transmission-Line Transformer, IEEE Microwave And

Wireless Components Letters, Vol. 16, No. 8, August 2006.

60

[10] Kai Chang, Inder Bahl, Vijay Nair, RF and Microwave Circuit and

Component Design for Wireless Systems, USA: Wiley, 2002.

[11] James Bao-Yen Tsui, Microwave Receiver with Electronic Warfare

Application, USA: Wiley, 1986.

[12] David L. Adamy, Introduction to Electronic Warfare Modeling and

Simulation, London: Artech House, 2003.

[13] Mike Golio, The RF and Microwave Handbook, CRC Press LLC, 2001.

[14] Kin-Lu Wong, Compact and Broadband Microstrip Antennas, USA: Wiley,

2002.

[15] Rainee N. Simons, Coplanar Waveguide Circuits, Components, and

Systems, USA: Wiley, 2001.

[16] White, Joseph F, High Frequency Techniques: An Introduction to RF and

Microwave Engineering, USA: Wiley, 2004.

[17] Bahl, I. J. Lumped Elements for RF and Microwave Circuits, London:

Artech House, 2003.

[18] Jia-Sheng Hong, M. J. Lancaster, Microstrip Filters for RF/Microwave

Applications, USA: Wiley, 2001

[19] K. C. Gupta, Microstrip Lines and Slotlines, 2nd Edition, London: Artech

House, 1996.

[20] Daniel G. Swanson, Jr., Microwave Circuit Modeling Using

Electromagnetic Field Simulation, London: Artech House, 2003.

[21] Inder Bhal, Microwave Solid State Circuit Design, 2nd Edition, USA: Wiley,

2003.

61

[22] Laverghetta, Thomas S. Microwaves and Wireless Simplified, 2nd Edition,

London: Artech House, 2005.

[23] Misra, Devendra, Radio Frequency and Microwave Communication

Circuits: Analysis and Design, 2nd Edition, USA: Wiley, 2004.

[24] Kai Chang, RF and Microwave Wireless Systems, USA: Wiley, 2000.

[25] Naval Air Warfare, Electronic Warfare and Radar System Engineering

Handbook, Naval Air Warfare Centre, NAWCWPNS TP 8347, rev 2 of 1

April 1999.

[26] Lei Wu, Zengguang Sun, Hayattin Yilmaz, and Manfred Berroth, A Dual-

Frequency Wilkinson Power Divider: For a Frequency and Its First

Harmonic, IEEE Transactions On Microwave Theory And Techniques, Vol.

54, No. 1, January 2006.

[27] Dongke Zh, Yewen Zhang, Codirectional Coupler and Power Divider

Mixed Microstrip and Metamaterials with Lumped-Elements L-C,

Intemational Conference on Microwave and Millimeter Wave Technology

Proceedings, 2004.

[28] Homayoon Oraizi, Design and Optimization of Broadband Asymmetrical

Multisection Wilkinson Power Divider, IEEE Transactions On Microwave

Theory And Techniques, Vol. 54, No. 5, May 2006.

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