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IMAGE REJECT FILTER DESIGN BY USING DEFECTED GROUND STURCTURE FOR SATELLITE APPLICATION

NG YELING JESSI

This report is submitted in partial fulfillment of the requirements for the award of Bachelor of Electronic Engineering (Telecommunication) With Honours

Faculty Electronic and Computer Engineering University Technical Malaysia Malacca

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UNIVERSTI TEKNIKAL MALAYSIA MELAKA

FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA II

Tajuk Projek : IMAGE REJECT FILTER DESIGN BY USING DEFECTED GROUND STURCTURE FOR SATELLITE APPLICATION Sesi

Pengajian : 1 0 / 1 1

Saya ………..NG YELING JESSI………. (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)

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DECLARATION

“ I hereby declare that this report is the results of my work except for quotes as cited in the references.”

Signature : ……….

Author : ………….NG YELING JESSI...………

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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 (Telecommunication) With Honours.”

Signature : ……….

Supervisor’s Name : ……….NOOR AZWAN BIN SHAIRI……..

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DEDICATION

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ACKNOWLEDGEMET

I want first to acknowledge with special thanks and appreciation to my supervisor Mr. Noor Azwan bin Shairi for his guidance and opinions along my project duration. His precious advice, contributions and comments has given great help for me in order to complete my project successfully.

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ABSTRAK

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viii

ABSTRACT

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CONTENT

CHAPTER CONTENT PAGE

PROJECT TITLE i

DECLARATION ii

DEDICATION v

ACKNOWLEDGEMENT vi

ABSTRACT vii

ABSTRAK viii

CONTENT ix

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF APPENDIX xv

I INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 2

1.3 Research Objective 2

1.4 Scope of Study 2

1.5 Organization of Study 2

II LITERATURE REVIEW 4

2.1 Introduction 4

2.2 Characteristic of Defected Ground

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x

2.3 Equivalent Circuit of Defected Ground

Structure (DGS) 6

2.4 S-Parameters 8

2.5 Application of DGS in millimeter wave

frequency 9

2.6 Advantages of DGS 11

2.7 Computer-aided Design Software 11

2.8 Hybrid Microwave Integrated Circuits

(HMIC) 12

2.9 Direct Broadcast Satellite 14

2.9.1 Superheterodyne Receiver System 15

III METHODOLOGY 17

3.1 Introduction 17

3.2 Planning of Study 17

3.2.1 Problem Formulation 19

3.2.2 Define Objective and Scopes 19

3.2.3 Literature Review 19

3.2.4 Design Flows 19

3.2.4.1 Equivalent Circuit Design 21

3.2.4.2 Layout Design 24

3.2.4.3 Simulation 33

IV RESULTS AND DISCUSSION 34

4.1 Results 34

4.1.1 Schematic Design 34

4.1.2 Layout Design 37

4.1.2.1 Transmission Line Design 37 4.1.2.2 Defected Ground Structure Unit

Design 38

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V RECOMMENDATIONS AND CONCLUSION 42

5.1 Future Work 42

5.2 Conclusion 43

REFERENCE 44

APPENDICES 46

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xii

LIST OF TABLES

NO TITLE PAGE

2.1 Requirements of a circuit design. 13

2.2 Typical properties of common hard substrate materials. 14

4.1 Schematic Simulation Result. 35

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xiii

LIST OF FIGURES

NO TITLE PAGE

2.1 Some resonant structures used for Defected Ground

Structure (DGS) applications. 6

2.2 Three-dimensional (3D) view of a dumbbell DGS unit. 6 2.3 Equivalent circuit of the dumbbell circuit of DGS unit. 7 2.4 Butterworth-type one pole prototype low-pass filter

circuit. 7

2.5 Two port network 8

2.6 Simulated S-parameters for dumbbell DGS unit. 10

2.7 Direct Broadcast Satellite System (DBS). 15

2.8 Basic construction of the front end of Superheterodyne

Receiver. 16

2.9 Image Parameter 16

3.1 General flow chart. 18

3.2 Advanced Design System (ADS) 20

3.3 Flow chart of DGS circuit design 20

3.4 Flow chart of DGS layout design. 21

3.5 New Schematic Window. 22

3.6 S-parameter Simulation and DC Simulation. 22

3.7 Simulate button. 23

3.8 Tune Parameters button. 23

3.9 Alumina 99.6% substrate. 24

3.10 FR4 substrate in LineCalc. 25

3.11 New Layout Window 26

3.12 Unit/Scale settings 26

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xiv

3.14 Insert rectangle button. 27

3.15 The complete view of dumbbell shape design. 28

3.16 Complete design of DGS unit. 29

3.17 Alumina 99.6% substrate settings. 30

3.18 Metallization Layers settings. 31

3.19 Settings for each port. 31

3.20 Simulation Control windows 32

4.1 Schematic Design. 35

4.2 Frequency Responses S21 and S11. 36

4.3 Frequency Response S21 when the capacitance value drecreases. 36 4.4 Frequency Response S21 when the inductance value decreases. 37

4.5 Layout design of Defected Ground Structure. 39

4.6 Frequency response of the DGS by using FR4 substrate. 39 4.7 Frequency response of the DGS by using Alumina 99.6%

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xv

LIST OF APPENDIX

NO TITLE PAGE

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CHAPTER I

INTRODUCTION

1.1 Background

Nowadays, high performances, compact size and low cost are the stringent requirements that have to be fulfilled in modern microwave communication system. Defected Ground Structure (DGS) is one of the new structures to enhance the quality of the system. It is an etched periodic or non- periodic cascaded configuration defect in ground of a planar transmission line (e.g. microstrip, coplanar and conductor backed coplanar wave guide).The disturbance of the shield current distribution in the ground plane will changes the characteristics of transmission line. In brief, any defect etched in the ground plane of microstrip will consequence in increasing effective capacitance and inductance.

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1.2 Problem Statement

In most cases, the Bandpass Filter is used to sort out the unwanted image frequencies that received by the receiver system. There is less or no details study on the use of Bandstop Filter as Image Reject Filter in Superheterodyne Receiver System. Due to the bulky size and impedance matching issues for conventional filters, the Defected Ground Structure is applied in the Image Reject Filter. In this project, the application of Direct Broadcasting Satellite at Ku-band is chosen as a platform for Defected Ground Structure at high frequency.

1.3 Research Objective

The objective of this project is to design the Image Reject Filter by using Defected Ground Structure for Satellite application at Ku-Band.

1.4 Scopes of Study

The research project will focus on:

(a) Circuit modeling of Image Reject Filter by using Defected Ground Structure. (b) Layout design of of Image Reject Filter by using Defected Ground Structure. (c) Simulation and analysis of circuit modeling and layout design of Defected

Ground Structure.

The simulations and analysis of the project are carried out by using two different substrates – FR4 and Alumina 99.6%.

1.5 Organization of Study

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Chapter 1 contains the background of the problem statement, the objectives and the scopes of the study. In this chapter, it summarizes the progress of study and describes the plan to accomplish the study.

In Chapter 2, the information and theory of which is related to the research is studied and summarized. The source of the information is from journals, books, internet, articles and etc.

Chapter 3 describes overview of the research methods and how to conduct the research methods. The steps to perform the simulation and analysis will be included in this chapter.

Chapter 4 presented the result of simulation in table and graph form and the discussion of the result that obtained in details. The discussion will include the problems that encountered during the simulation of results. Alternative solutions will be proposed to improve the performance of Defected Ground Structure.

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CHAPTER II

LITERATURE REVIEW

2.1 Introduction

Recent years, there are new technologies in modern communication systems to boost up the whole quality of system. Most of passive and active microwave and millimeter devices are design to suppress the harmonics and realize the compact dimensions of circuits. The existent new technologies such as Low-temperature co-fire ceramic technology (LTCC), Low-temperature co-co-fire ferrite (LTCF) and some new structures such as Photonic band gap (PBG), Defected ground Structure (DGS), Substrate integrate wave-guide (SIW) are those which meet the rigid requirements of microwave communication system. As some of the listed technologies are facing the difficulties of modeling and radiation for the design of the microwave or millimeter-wave components, DGS is proposed to alleviate these problems [1].

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The design of DGS is where the ground plane metal of a microstrip (or stripline, or coplanar waveguide) circuit been modified on purpose to improve its performance. It is an etched periodic or non-periodic cascaded configuration which is defect in ground of a planar transmission line which disturbs the shield current distribution in the ground plane cause the defect in the ground [3]. The disturbance gives effect on the characteristic of transmission line. It increases the effective capacitance and inductance.

2.2 Characteristics of Defected Ground Structure (DGS)

The basic element of DGS is a resonant gap or slot in ground metal, placed directly under a transmission line and aligned for efficient coupling to the line. Figure 2.1 shows some resonant structures used for defected ground structure applications. Each differs in the occupied area, equivalent L-C ratio, coupling coefficient, higher-order responses, and other electrical parameters [2]. To fulfill different requirements for bandwidth (Q) and center frequency, a variety of DGS shapes have introduced (e.g. dumbbell, periodic, fractal, circular, spiral, L-, and H- shapped structures where the shape does not overlap other portions of the circuit.

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[image:21.595.128.514.70.252.2]

6

Figure 2.1: Some resonant structures used for Defected Ground Structure (DGS) applications [2].

Figure 2.2: Three-dimensional (3D) view of a dumbbell DGS unit [3].

2.3 Equivalent Circuit of Defected Ground Structure (DGS)

[image:21.595.183.459.340.571.2]
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[image:22.595.229.411.217.341.2]

to be calculated by full-wave electromagnetic (EM)-simulation in order to explain the cutoff and attenuation pole characteristics of the DGS section [1]. However, there is no correlation between the physical dimensions of DGS and the equivalent LC parameters. Parametric study is used to correlate between the layout design and equivalent circuit of the DGS. Hence, conventional methods are time consuming and the result is not predictable [1, 4-5].

[image:22.595.230.411.421.525.2]

Figure 2.3: Equivalent circuit of the dumbbell circuit of DGS unit.

Figure 2.4 – Butterworth-type one pole prototype low-pass filter circuit.

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To match the DGS with the Butterworth low pass filter as shown in Figure 2.4, the reactance value of both circuit are equal at cutoff frequency. The radiation effects are neglected as there is less radiation by the DGS unit if compared with the periodic Photonic Bandgap structure [4]. In this project, a single DGS unit is used. Hence, the L and C are derived as follows [8]:

XLC

=

w1oC

(

wo

w

-

wwo

)

(2.1)

where wo is the resonance frequency of parallel LC resonator.

C = wo Zog1

(

1 w2

o- w2c

)

(2.2)

L = 1/4π2fo2C (2.3)

where the fo = resonance (attenuation pole), fc is the cutoff frequency.

2.4 S-parameters

[image:23.595.243.395.647.701.2]

Scattering parameters (the elements of scattering matrix or S-matrix) define the electrical behaviors of linear electrical networks when stimulated by electrical signals. It is widely used in radio frequency (RF) and microwave circuit design to describe both active and passive devices’ electrical behaviors as shown in Figure 2.5 The electrical properties of networks of components (inductors, capacitors and resistors) can be expressed as gain, return loss, voltage standing ratio (VSWR), reflection coefficient and amplifier stability by S-parameters.

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The designed circuit will be analyzed in two port network. The relationship between the reflected, incident power wave and S-parameter can be expressed in matrix below [13]:

�b1b2

=

�S11S21S12S22� �a1a2� (2.4)

by expanding the matrices into equations:

b1 = S11a1 + S12a2 b2 = S21a1 + S22a2 (2.5)

Each 2-port S-parameter has the following descriptions:

• S11 is the input port voltage reflection coefficient.

• S12 is the reverse voltage gain.

• S21 is the forward voltage gain.

• S22 is the output port voltage reflection coefficient.

In this paper, S21 and S11 are the main concerns as S21 shows the insertion lost of the filter which is in dB expression of the transmission coefficient where as S11 shows the input return loss of the system.

2.5 Advantages of DGS

Figure

Figure 2.1: Some resonant structures used for Defected Ground Structure (DGS)
Figure 2.3: Equivalent circuit of the dumbbell circuit of DGS unit.
Figure 2.5: Two port network

References

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