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DESIGN A MICROSTRIP HAIRPIN BANDPASS FILTER FOR GPS

APPLICATION

NORBAIZURA BINTI DAHALAN

This report is submitted in partial fulfillment of the requirements for the award of

Bachelor of Electronic Engineering (Telecommunication Electronics) with Honours

Faculty of Electronic and Computer Engineering

Universiti Teknikal Malaysia Melaka

APRIL 2011

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UNIVERSTI TEKNIKAL MALAYSIA MELAKA FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

BORANG PENGESAHAN STATUS LAPORAN

PROJEK SARJANA MUDA II

Tajuk Projek : ………………………………………………………………………………

Sesi Pengajian : ………………………………………………………………………………

Saya …………………………………………………………………………………………………..

(HURUF BESAR)

mengaku membenarkan Laporan Projek Sarjana Muda ini disimpan di Perpustakaan dengan syarat-syarat kegunaan seperti berikut:

1. Laporan adalah hakmilik Universiti Teknikal Malaysia Melaka.

2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja.

3. Perpustakaan dibenarkan membuat salinan laporan ini sebagai bahan pertukaran antara institusi

pengajian tinggi.

4. Sila tandakan ( √ ) :

SULIT*

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972)

TERHAD* (Mengandungi maklumat terhad yang telah ditentukan oleh

organisasi/badan di mana penyelidikan dijalankan)

TIDAK TERHAD

Disahkan oleh:

__________________________ ___________________________________ (TANDATANGAN PENULIS) (COP DAN TANDATANGAN PENYELIA)

Alamat Tetap:

Tarikh: ……………………….. Tarikh: ………………………..

DESIGN A MICROSTRIP HAIRPIN BANDPASS FILTER FOR GPS APPLICATION

2010/2011

NORBAIZURA BINTI DAHALAN

NO 33 JALAN BAYAN 10 TAMAN BUKIT KATIL 75450 MELAKA

APRIL 2011 APRIL 2011

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“I hereby declare that this report is the result of my own work except for quotes as cited

in the references.”

Signature :……………………………

Author : NORBAIZURA BINTI DAHALAN

Date : APRIL 2011

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“I hereby declare that I have read this report and in my opinion this report is sufficient in

terms of the scope and quality for the award of Bachelor of Electronic Engineering

(Electronics Telecommunication) With Honors.”

Signature :………………………………..

Supervisor‟s Name : EN. AZAHARI BIN SALLEH

Date : APRIL 2011.

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Dedicated to my family, lectures and to all my friends,

My appreciation to all of you for providing me assistance and encouragement throughout

my final year project in Universiti Teknikal Malaysia Melaka (UTeM)

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ACKNOWLEDGEMENTS

Assalamualaikum w.b.t

First and foremost, I would like to praise Allah for His blessing. He gave me

physical and mental strength to carry on my final year project up to completion. Final

year project is a subject for final year student and this subject will help students to apply

their skill and knowledge by hands-on, which gained from the lecturer. During the

completion or implementation of this project, student will face several problems. Be the

future engineer, the most important is to be technically strong as well as good in analysis

and problem solving method skill through hands-on opportunity.

I wish to express my appreciation for my project supervisor, Mr Azahari Bin

Salleh for his excellent supervision, advices, suggestion, and comment throughout the

completion and implementation of this project.

Finally, my deepest gratitude goes to my beloved family members for their

constant support, encouragement and prayer. Not forgetting all my friends at FKEKK for

their help that directly and indirectly contributed to the accomplishment of this project.

Thank you to all.

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ABSTRACT

This project is mainly focused on development of microwave filter by using

bandpass filter principle. The reason of this project is to develop the microwave used

widely in the application and to provide the graduate engineer with knowledge about the

potential of the microwave technique to implement practical microwave. Microwave

frequencies generally operate at frequencies between 300 MHz and 300 GHz. Filter is

highly desirable in communication systems. It functions to pass through the desired

frequencies within the range and block the unwanted frequencies. In addition, filters are

also needed to remove out the harmonics that are present in the communication system.

This thesis presents the design of a hairpin bandpass filter. The main objective of this

project is to design bandpass filter of reduced size and enhanced bandwidth. This filter

are designed by using the specification as using the Chebyshev response of 0.5 dB

ripples and hairpin filter for frequency 1.575 GHz. It was found that the optimum

designed filter has a centre frequency of 1.575 GHz, exhibits excellent return loss in the

passband of less than -20 dB. Consequently, the proposed filter is not only of compact

size, it also exhibits excellent good return loss by using the AWR and CorelDRAW

software.

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ABSTRAK

Projek ini yang utama difokuskan pada pembangunan gelombang mikro dengan

menggunakan prinsip penapis jalurlulus. Projek ini adalah bertujuan untuk

mengembangkan lagi bidang gelombang mikro yang mana sering digunakan secara

meluas di dalam aplikasi dan untuk menghasilkan graduan jurutera dengan pengetahuan

tentang potensi teknik gelombang mikro untuk melaksanakan ianya secara praktikal.

Umumnya, gelombang mikro berfungsi pada frekuensi di antara 300 MHz dan 300 GHz.

Ini juga menceritakan tentang peranti penapis yang sangat diperlukan dalam sistem

komunikasi. Ia berfungsi bagi membenarkan satu julat frekuensi yang dikehendaki. Di

samping itu, penapis juga diperlukan untuk membuang harmonic yang tidak dikehendaki

dalam sesebuah sistem komunikasi. Tesis ini membentangkan rekabentuk penapis jenis

penyalun „hairpin‟. Objektif utama projek ini adalah untuk merekabentuk penapis

penyalun rambut (hairpin) dengan pengurangan saiz dan lebar jalur lebih luas. Penapis

penyalun rambut direka dengan spesifikasi seperti bertatarajah dalam rekaan penyalun

rambut dengan menggunakan tindakbalas Chebyshev dengan ripple 0.5dB pada

frekuensi 1.575 GHz. Kehilangan kembali yang sangat baik dalam penapis iaitu kurang

daripada -20 dB. Penapis ini bukan saja bersaiz padat tetapi mempunyai kehilangan

kembali yang lebih rendah dengan menggunakan perisian AWR dan CorelDRAW.

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CONTENTS

CHAPTER CONTENTS PAGE

PAGE TITLE i

STATUS FORM ii

DECLARATION iii

DEDICATION v

ACKNOWLEDGEMENT vi

ABSTRACT vii

ABSTRAK viii

CONTENTS ix

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF SYMBOLS xv

LIST OF APPENDIX xvi

I INTRODUCTION

1.1 Project Background 1

1.2 Problem Statement 2

1.3 Objective 2

1.4 Work Scope Project 2

1.5 Thesis Outline 3

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II GLOBAL POSITIONING SYSTEM (GPS)

2.1 GPS Overview 4

2.2 GPS System Segment 5

2.3 GPS Receiver Architecture 6

III FILTER THEORY

3.1 Introduction 8

3.2 Filter Parameters Definition 11

3.2.1 Scattering Parameters 12

3.2.2 Insertion Loss 14

3.2.3 Return Loss 15

3.3 Filter Synthesis Technique 16

3.3.1 Insertion Loss method 16

3.4 Basic Filter Types 17

3.5 Bandpass Filter 18

3.6 Filter Response 20

3.6.1 Chebyshev Response 20

3.6.1.1 Advantage and Disadvantages 21

3.6.1.2 Table Response 22

3.6.2 Butterworth Response 23

3.6.2.1 Advantage and Disadvantages 23

3.6.2.2 Table Response 24

3..6.3 Comparison Response 24

3.7 Microstrip Transmission Lines 25

3.8 Hairpin Bandpass Filter 26

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IV METHODOLOGY

4.1 Introduction 28

4.2 Methodology 28

4.3 Design Specification 30

4.4 Design Filter Step 31

4.4.1 Determine the Values of Prototype Element 32

4.4.2 Determine the Value of Low-pass Prototype 32

4.4.3 Obtain the Characteristic Impedance 34

4.4.4 Determine Widths Separations and Length 34

4.4.5 Design AWR Simulation 36

4.4.6 Fabrication and Testing 37

4.4.7 Measurement Process 37

V RESULT AND DISCUSSION

5.1 Introduction 38

5.2 Simulation Result 38

5.2.1 Microstrip Design using FR4 Board 39

5.3 Measurement Result 43

VI CONCLUSION AND RECOMMANDATION

6.1 Conclusion 46

6.2 Suggestion 47

REFERENCES 48

APPENDIX

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LIST OF TABLES

NO TITLE PAGE

3.1 Ripple factor 22

3.2 Ripple factor 22

3.3 Butterworth nth Response 24

4.1 Filter Specification 30

4.2 FR4 material specification 31

4.3 Ripple factor 32

5.1 The value of series and parallel for LC circuit 39

5.2 The value of even and odd characteristic impedance 41

5.3 The value of resonator length, width and gap 42

5.4 Comparison of Result 45

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LIST OF FIGURE

NO TITLE PAGE

2.1 Three Segment of GPS System 5

2.2 GPS Receiver Architecture 7

3.1 General form of a filter network 10

3.2 Equivalent circuit power transfer calculations 10

3.3 Dissipative filter 11

3.4 An n-port network 12

3.5 A 2-port network 12

3.6 Example of return loss and insertion loss response 15

3.7 The Ideal Filter 17

3.8 Non-ideal filter 18

3.9 Band pass filter consisting of low pass and high pass filters 19

3.10 Low Pass profile of Chebyshev and Butterworth response 24

3.11 Microstrip Hairpin Filter 25

3.12 Electric fields in microstrip 26

3.13 Microstrip Hairpin Filter 27

4.1 Flow Chart of design methodology 29

4.2 FR4 board Illustration 31

4.3 Hairpin Resonator 31

4.4 Prototype filter transformations 33

4.5 Graph determining w and l 35

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4.6 Fabrication Layout 37

5.1 Lumped element for 5th order bandpass filter 40

5.2 Frequency response bandpass filter using lumped element 40

5.3 The Hairpin filter Layout 42

5.4 The response of hairpin filter design 43

5.5 Fabrication of Bandpass filter 44

5.6 Measurement Graph 44

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LIST OF SYMBOLS

AWR Microsoft Office RF/Microwave

GPS Global Positioning System

RL Return loss

IL Insertion Loss

PR Power Reflected

EM Electromagnetic

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LIST OF APPENDIX

NO TITLE PAGE

A Table of Response 51

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CHAPTER I

INTRODUCTION

This chapter will discuss the overview process that involved for this project;

the aims and specific project background, problem statements, objective of the

project and work scope. The end of this chapter the thesis outline will be listed.

1.1 Project Background

A microwave filter is an electromagnetic circuit that consists of two ports

network. It controls the frequency at certain point or region in a microwave system,

by providing transmission at frequencies within the passband of the filter and

attenuation at its stopband of the filter [1]. Filters are easily found in applications

such as microwave communication, wireless communication, global positioning

system and measurement system [1]. Bandpass filter is widely used in the

telecommunication system, be it in receiving or transmitting devices, to filter out

unwanted frequency. There are plenty of ways to design the filter, and most attractive

among them is microstrip filter due to the compact structure and fairly easy to be

manufactured [2]. There has been much research on hairpin resonator. The main

purpose of all these project is to make the filters more compact in size and shape [3].

The conventional filter was too space consuming. The concept of miniaturize hairpin

resonator was design for Global Positioning System (GPS) that nowadays are most

familiar.

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1.2 Problem Statement

Filter is one of the most important components in an electronic circuit. The

problem statement of this project is to analyze what will be faced when there is no

filter circuit in GPS system. Without an automatic filter tuning circuit, it can‟t keep

the cut-off frequency of the filter constant and structure will run with unwanted

signal. The conventional filter is built in concept integrates lumped element which

have a large size, so we solve to reduce the size of bandpass filter by using hairpin

resonator.

1.3 Objective

The objective of this project is to design, simulate and fabricate a microstrip

hairpin bandpass filter that operating at frequency 1575.60 MHz for Global

Positioning Application (GPS) with bandwidth 12%, insertion loss >-1 dB and return

loss < -20dB.

1.4 Work Scope

The project is designing a suitable microstrip bandpass filter structure for

GPS application with frequency LI is 1575.60 MHz. The configuration is modified to

reduce the size of the fractal filter. The Microsoft Office RF Design (AWR) is used

to design and simulate the conventional filter. For hardware implementation and

fabrication, Coral DRAW is used for actual printed circuit layout. The parameters

performances of the filter are analyses in term of return loss < -20dB, insertion loss

>-3dB, and bandwidth 12% and so on to have the optimum configuration microstrip

bandpass filter for GPS. The project scopes are as following:

(a) Literature reviews of band pass filter design and software‟s that are available.

(b) Design microstrip band pass filters with using mathematical software.

(c) Simulating the designed filters with AWR software.

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(d) Analyze the characteristics and performance of the designed filters to

determine the ideal filter structure and become the optimum design where the

parameters in term of loss < -20dB, insertion loss >-3dB, and bandwidth 12%

(e) Fabricate optimum design filter into respective multilayer with FR4 substrate

(f) Configurations simulate and measured the performance of the filter.

1.6 Thesis Outline

The report consists of six chapters. Chapter I present the objective, problem

statements, objective, project scope and thesis outlines.

Chapter II discusses the basic theory on Global Positioning System (GPS)

that are the main application have been choose for designing this project. It also

explained the location of this project onto the GPS system.

Chapter III presents about the filters that relevant to this project. These

include S-parameters application in microwave circuits, a brief discussion on the

subject and equations concerning the theory were presented. Filter synthesis

technique method were described together with discussion on filter response. This

chapter also covers theories of resonator miniaturization, hairpin filter realization and

characteristics of internal coupled resonator.

Chapter IV presents design methodology, specification and the discussion on

the tools involved for circuit simulation.

Chapter V discusses the result and analysis of the findings. These include the

study of resonator behaviour and all parameter variations that affect filter

performance as whole. Discussion and comparison of the filter performances are

made, for the single and multilayer configurations.

Finally, chapter VI covers the project conclusion of the thesis and discussion

deep details on recommendation and possible future work that can be done to

enhance the application of miniaturize resonator and improve the performance.

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CHAPTER II

GLOBAL POSITIONING SYSTEM (GPS)

There are several types of system that involved in user needed that used a

filter in their structure, such as GPS system, W-LAN system, GPS system, Infra-red

system and others. In this project, the GPS system application is used for the

designing the filter. In this chapter will discusses the basic theory on Global

Positioning System (GPS) that are the main application have been choose for

designing this project. It also explained the location of this project onto the GPS

system.

2.1 GPS Overview

GPS is fully operational and meets the criteria established in the 1960s for an

optimum positioning system. The system provides accurate, continuous, worldwide,

three-dimensional position and velocity information to users with the appropriate

receiving equipment. GPS also disseminates a form of Coordinated Universal Time

(UTC). The satellite constellation nominally consists of 24 satellites arranged in 6

orbital planes with 4 satellites per plane. A worldwide ground control/monitoring

network monitors the health and status of the satellites. This network also uploads

navigation and other data to the satellites. GPS can provide service to an unlimited

number of users since the user receivers operate passively (i.e., receive only).

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The system utilizes the concept of one-way time of arrival (TOA) ranging.

Satellite transmissions are referenced to highly accurate atomic frequency standards

onboard the satellites, which are in synchronism with a GPS time base. The satellites

broadcast ranging codes and navigation data on two frequencies using a technique

called code division multiple access (CDMA); that is, there are only two frequencies

in use by the system, called L1 (1,575.42 MHz) and L2 (1,227.6 MHz). Each satellite

transmits on these frequencies, but with different ranging codes than those employed

by other satellites.

2.2 GPS System Segment

Figure 2.1: Three Segment of GPS System [4]

GPS is comprised of three segments: satellite constellation, ground-

control/monitoring network, and user receiving equipment. Formal GPS JPO

programmatic terms for these components are space, control, and user equipment

segments, respectively as shown in Figure 2.1,

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The satellite constellation is the set of satellites in orbit that provide the

ranging signals and data messages to the user equipment. The control segment (CS)

tracks and maintains the satellites in space [4]. The CS monitors satellite health and

signal integrity and maintains the orbital configuration of the satellites. Furthermore,

the CS updates the satellite clock corrections and ephemerides as well as numerous

other parameters essential to determining user PVT. Finally, the user receiver

equipment (i.e., user segment) performs the navigation, timing, or other related

functions (e.g., surveying). There are three segments of GPS which is space segment,

control segment and user segment.

(a) The space segment (satellites)

Broadcast radio signals toward users on the Earth and receive commands

from the ground

(b) The control segment

Monitors the space segment and send commands to satellites

(c) The user segment

Receivers record and interpret the radio signals broadcast by the satellites

For this project just focus a primary signal at 1.575 GHz (L1 band). The basic

GPS diagram is a transmitter, satellite and receiver part. For GPS system, both part

transmitter and receiver are including the use of filter.

2.3 GPS Receiver Architecture

The GPS system has been fully operational with 24 satellites in its

constellation since 1994. It is used by millions of people, both civilian and military,

every day. The fundamental concept of using code-division multiple access (CDMA)

for time-delay measurement (yielding range) while allowing all satellites to share the

same carrier frequency 1.57542 GHz has not changed in the past 30 years. Each GPS

satellite uses a unique 1,023-chip orthogonal code (Gold code) to spread the low-

speed binary phase shift keying (BPSK, 20 ms per bit) navigation data bitstream. The

chipping clock rate is 1.023 MHz, and therefore the sequence of 1,023 chips repeats

every millisecond.

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The GPS receiver generates a local copy of the same Gold code, which is

then cross-correlated with the incoming signal. When the receiver code phase aligns

with the incoming signal code phase, there is a +30 dB improvement in the SNR, and

the BPSK navigation bit stream can then be easily detected. Roughly speaking, you

can use the local code time offset, where the correlation is maximized to estimate the

time difference between the received signal and the signal transmitted by the

satellite. The range is directly proportional to time; therefore, with four satellite

ranges, and knowing the positions of the satellites, you can navigate.

The Receiver for the GPS system consist of LNA with high front-end gain, a

active type I/O down conversion mixer, and baseband circuits which perform

amplification and filtering [4]. As shows in Figure 2.2, the hairpin bandpass filter

that design in this project are located at the block of PPF. The bandpass filter are

used to remove unwanted signal of frequency that‟s capture from the receiver

antenna.

Figure 2.2: GPS Receiver Architecture [4]

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CHAPTER III

FILTER THEORY

This chapter is represents about the filters that relevant to this project. These

include S-parameters application in microwave circuits, a brief discussion on the

subject and equations concerning the theory were presented. Filter synthesis

technique method were described together with discussion on filter response. This

chapter also covers theories of resonator miniaturization, hairpin filter realization and

characteristics of internal coupled resonator.

3.1 Introduction

Filters are used for the rejection of unwanted signal frequencies but

permitting good transmission of wanted frequencies. An automatic filter tuning

circuit keeps the cut-off frequency of the filter constant despite the environmental

variations in the supply voltage and temperature [2]. In this chapter, an explanation

about microwave filter theory and scattering parameters are given. In addition, basic

theory of microstrip transmission line is also given.

Most microwave systems consist of many active and passive components that

are difficult to design and manufacture with precise frequency characteristics. In

contrast, microwave passive filters can be designed and manufactured with

remarkably predictable performance. As a result, microwave systems are usually