The E And H Antenna Design For Broadband Application.
THE E AND H ANTENNA DESIGN FOR BROADBAND APPLICATION
NURUL HANIS BINTI MOHAMAD NASIR
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THE E AND H ANTENNA DESIGN FOR BROADBAND APPLICATION
NURUL HANIS BINTI MOHAMAD NASIR
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
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UNIVERSTI TEKNIKAL MALAYSIA MELAKA
FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER
BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA II
Tajuk Projek : THE E AND H ANTENNA DESIGN FOR BROADBAND
APPLICATION Sesi
Pengajian : 2008/2009
Saya NURUL HANIS BINTI MOHAMAD NASIR
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:
LOT 1238, BATU 1, JLN MERANTI, 17000 PASIR MAS, KELANTAN.
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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 : Nurul Hanis Binti Mohamad Nasir
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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 Electronics) With Honours.”
Signature : ………
Supervisor’s Name : Mr. Mohamad Zoinol Abidin Bin Abd. Aziz
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ACKNOWLEDGEMENT
I would like to thank the God, as with His blessings, I managed to complete this Final Year Project. One of the great pleasures of writing a thesis is acknowledging the efforts of many people and to those that may not appear on the cover, but whose contribute to this thesis. First of all, I would like to forward special note of thanks to my project supervisor, which is Mr. Mohamad Zoinol Abidin Bin Abd. Aziz who has been very kind to help me through this project. He had provides precious guidelines and a lot of helpful comments. Special gratitude goes out to my family specially my parents, for showing their concern and loves to me in my years in UTeM while backing me all the way right up to the completion of this project. Finally, special thanks to all my friends and course mates which are too many to be listed here for their knowledge sharing and supporting in assisting me toward finalizing and completing this project. Last but not least to all whose contribute in these project direct or indirectly. Thank you again.
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ABSTRACT
The major weakness of a conventional microstrip patch antenna is its narrow bandwidth. A E and H antenna is designed based on the structure of E and H itself to have a wider bandwidth to overcome this problem. The broadband characteristic is obtained by proper selecting the E and H structure. Two parallel slots and two series slots are incorporated into the patch antenna. The parallel slots reduce the size of the antenna, while the series slots reduce the return loss of the antenna. The H antenna is designed based on stepped impedance resonator while E antenna is based on transmission line model. Then, by intersecting both antennas, the E and H antenna is obtained. The E and H antenna has a compact dimension of 42.36 23.77mm2. The simulation of the antenna is carried out to obtain the return loss, bandwidth, gain, directivity and radiation pattern. Next, the antenna is fabricated on FR4 board. The E
and H antenna offers a low profile, broadband and a compact antenna element. Measurement results also showed satisfactory performance of the antenna with an achievable bandwidth of 65.6%. The directivity of this antenna is 3.538dBi with achievable gain of -25.9dB which is an inefficient value of gain for an antenna.
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ABSTRAK
Kelemahan utama antena konvensional mikrostrip tompok merupakan lebar jalurnya yang sangat kecil. Antena E dan H telah direka berdasarkan struktur huruf E dan H itu sendiri untuk mempunyai lebar jalur yang lebih besar untuk mengatasi masalah ini. Struktur E dan H yang sesuai perlu dipilih untuk memperoleh ciri-ciri jalur lebar. Dua alur selari dan dua alur sesiri digabungkan ke dalam satu mikrotrip tompok antena. Alur selari dapat mengecilkan saiz antena, manakala alur sesiri pula dapat mengurangkan kehilangan kembali sesuatu antena. Antenna H direka berdasarkan alat resonans langkah galangan manakala antenna E pula berdasarkan model talian transmisi. Selepas itu, dengan menyilangkan kedua-dua bentuk itu, antenna E dan H diperoleh. Antenna berbentuk E dan H mempunyai dimensi sebanyak 42.36 23.77mm2. Simulasi untuk antenna ini adalah bagi mendapatkan kehilangan balikan, lebar jalur, gandaan, keterarahan dan juga corak radiasi. Selepas itu, antenna difabrikasikan menggunakan papan FR4. Antena ini menyumbangkan ciri-ciri sebuah antena dengan lebar jalur beserta saiz yang lebih kompak dan ringan. Keputusan pengukuran adalah memuaskan dengan pencapaian lebar jalur sebanyak 65.6%. Keterarahan antena ini ialah sebanyak 3.538dBi manakala gandaan bagi antenna ini ialah sebanyak -25.9dB di mana nilai gandaan yang negatif merupakan satu nilai gandaan yang tidak efisien bagi sesebuah antenna.
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TABLE OF CONTENTS
CHAPTER DETAILS PAGE
PROJECT TITLE i
AUTHENTICATION FORM ii
AUTHOR’S DECLARATION iii
SUPERVISOR’S DECLARATION iv
DEDICATION v
ACKNOWLEDGEMENT vi
ABSTRACT vii
ABSTRAK viii
CONTENTS ix
LIST OF TABLES xii
LIST OF FIGURES xiii
LIST OF ABBREVIATION xvi
LIST OF APPENDICES xviii
1 INTRODUCTION
1.1 Introduction 1
1.2 Objectives 2
1.3 Problem Statement 3
1.4 Scope 3
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2 LITERATURE REVIEW
2.1 Fundamental Parameters of Antenna 6
2.2 Microstrip Patch Antennas 7
2.3 The E and H antenna design 8 2.3.1 L-Probe Fed Antenna 9
2.3.1.1 E-shaped Microstrip Patch 9 Antennas
2.3.1.2 A 4x1 Hybrid E-H Microstrip 11 Patch Antenna Array
2.3.2 H-shaped Patch Antenna 13 2.3.3 Wide-Band E-Shaped Patch Antennas 16 2.3.4 IHI slot antennas 18
3 E AND H MICROSTRIP ANTENNA DESIGN
3.1 Design Procedure 20
3.1.1 H antenna 21
3.1.1.1 Different impedance ratio, K design 21
3.1.2 E antenna 24
3.1.3 E and H antenna 26
3.2 Simulation Setup 27
3.2.1 H antenna simulation 28 3.2.2 E antenna simulation 29 3.2.3 E and H antenna simulation 29
3.3 Fabrication 30
4 RESULTS ANALYSIS AND DISCUSSION
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4.1.1 Different impedance ratio design 33 4.1.2 Analysis of the length, L of H antenna 35 4.2 E antenna design result 40
4.2.1 Analysis of slot length, Ls 40
4.2.2 Analysis of slot position, Ps 41
4.3 E and H antenna design result 46
5 CONCLUSION AND SUGGESTIONS
5.1 Conclusion 49 5.2 Suggestions 50
REFERENCES 51
APPENDIX A 53
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LIST OF TABLE
NO TITLE PAGE
3.1 The effect of varying the impedance ratio on the resonator length 22 4.1 The effect of varying the length of the H antenna 35 4.2
4.3 4.4 4.5 4.6 4.7 4.8
The return loss and bandwidth of optimized H antenna The half power beam-width for H antenna
The results for varying the slot position
Comparison of return loss between Design 1 and Design 2 The half power beam-width for E antenna
The simulation results for E and H antenna The half power beam-width for E and H antenna
35 39 41 43 45 47 48
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LIST OF FIGURES
NO TITLE PAGE
1.1 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11
Design flow diagram for E and H antenna A rectangular microstrip patch antenna
The L-Probe Inverted E-shaped patch antenna (top view) The side view of E-shaped patch antenna
The top view of LIEH shaped patch antenna The side view of LIEH shaped patch antenna The stepped impedance resonator structure The H-shaped patch antenna
Geometry of a wide-band E-shaped patch antenna consisting of two parallel slots in the patch
The slot antenna geometries cut in a ground plane The H slot antenna geometries cut in a ground plane The IHI slot antenna geometries cut in a ground plane
4 8 9 10 12 12 13 15 17 18 18 19
3.1 The H-shaped antenna 21
3.2 Design 1 of H antenna 23
3.3 The design flow process for H-shaped antenna 23
3.4 The E-shaped antenna 24 3.5 Design 1 of E antenna 25
3.6 The design flow process for E- shaped antenna 25
3.7 The intersect process of E and H antenna 26
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3.9 The side view of antenna design 28
3.10 The top view of H antenna design 28
3.11 The top view of E antenna 29
3.12 The top view of E and H antenna 30 3.13 The flow chart of fabrication process 31 3.14 The fabricated E antenna, H antenna and E and H antenna 32 4.1 The return loss for different impedance ratio 34 4.2 The return loss for Design 1 of H antenna 34 4.3 The effect of varying the L2 36
4.4 The return loss for Design 2 of H antenna 37
4.5 Design 2 of H antenna 37
4.6 Comparison of return loss between simulation and measurement 38 result for H antenna
4.7 The radiation pattern for H antenna (a) E-E plane. (b) H-H plane. 39 4.8 The changes in resonant frequency for varying the slot length 40
4.9 The graph for varying the slot position 42
4.10 Design 2 of E antenna 42
4.11 The comparison of return loss for Design 1 and Design 2 43 4.12 Comparison of return loss between simulation and 44
measurement result for E antenna
4.13 The radiation pattern for H antenna (a) E-E plane (b) H-H plane. 45 4.14 The return loss of E and H antenna 46
4.15 The comparison of return loss between simulation and 47 measurement result for E and H antenna
4.16 The radiation pattern for E and H antenna 48 (a) E-E plane (b) H-H plane
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LIST OF ABBREVIATION
ΔL - Length extension
θ - Resonator length
ℰeff - Effective dielectric constant
ℰr - Dielectric constant
BMPAA - Broadband Microstrip Patch Antenna Array
BW - Bandwidth
CST - Computer Simulation Technology
Do - Maximum directivity
dB - Decibel
fr - Resonant frequency
FR4 - Flame Retardant 4
h - Height of dielectric substrate HPBW - Half power beam-width
IEEE - Institute of Electrical and Electronics Engineers IMT - International Mobile Telecommunication
K - Impedance ratio
L - Length
LIEH - L-Probe fed Inverted Hybrid E-H
Ls - Slot length
PCB - Printed Circuit Board
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Ps - Slot position
SWR - Standing Wave Ratio
Umax - Maximum radiation intensity
UV - Ultra-violet
W - Width
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LIST OF APPENDICES
NO TITLE PAGE
A Different value of K 53
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CHAPTER 1
INTRODUCTION
1.1 Introduction
A conventional microstrip patch antenna has been very popular due its numerous advantages such as low profile, light weight, and compatible with microwave integrated circuit but the major weakness is its narrow bandwidth [1-6]. The bandwidth of the conventional microstrip patch antenna is only about 11.2 MHz [7]. The E and H antenna is designed based on the character E and H itself. The purpose of this project is to design an antenna for broadband application that can operate with a wider bandwidth compared to conventional microstrip patch antenna. The broadband resonant can be obtained by proper selecting the structure of E and H. An end-loaded slot antenna can be used to reduce the length of a slot antenna without changing its resonant frequency.
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A novel H-shaped patch antenna is proved to have a smaller size, less number of modes, absence of harmonic resonance, and the provision of pure reactive impedances at its harmonic resonance, and the provision of pure reactive impedances at its harmonics that can result in increased transmitter efficiency [8].
In the other hand, a wide-band E-shaped patch antenna is introduced. Two parallel slots are incorporated into the patch of a microstrip antenna to expand it bandwidth. When two parallel slots are incorporated into the antenna patch, the bandwidth increases above 30% from the conventional microstrip patch antenna [9].
A novel wideband L-Probe fed inverted hybrid E-H shaped microstrip patch antenna (LIEH) covering the International Mobile Communications – 2000 (IMT-2000) band is designed that adopts contemporary techniques such as L-probe feeding, inverted patch structure with air-filled dielectric and slotted patch. The results is an antenna with an achievable bandwidth of 17.20% at 14 dB return loss (SWR=1.5) [10].
1.2 Objectives
The objectives of this project are to design an E and H shaped antenna that can operate at broadband frequencies. The suitable width and length of the desired antenna will be determine by proper selecting the E and H structure that will satisfy the broadband resonant. The return loss of the antenna is expected to be less than -10 dB and the bandwidth of the antenna is wider than the bandwidth of the conventional microstrip patch antenna.
1.3 Problem Statement
A conventional microstrip patch antenna is known to have many advantages but the major weakness is its narrow bandwidth. A bandwidth is the difference between the
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highest frequency and the lowest frequency. An antenna that has a wider bandwidth is suitable for broadband application. In addition, the antenna with smaller size is an advantage [8].
1.4 Scope
The scope of this project is to design an E and H antenna with suitable width, W
and length, L for broadband application. The simulation of return loss and bandwidth of the antenna is carried out using Computer Simulation Technology (CST) Microwave Studio. The optimization of H antenna involved its impedance ratio and resonator length. However, the optimization of E antenna involved its slot position and slot length. Next, after it satisfy the require condition, the antenna is fabricated on FR4 board using chemical etching technique. The antenna’s performance is measured such as its bandwidth, gain, directivity, return loss, radiation pattern and etc.
1.5 Methodology
Figure 1 shows the design flow diagram for E and H antenna design. Firstly, to obtain enough information about this project, a literature review is carried out from journals and books. After that, the design process started with calculation for antenna parameters for example the width and length, by referring to the method that has been reviewed. Then, the simulation of return loss, bandwidth, radiation pattern and etc is carried out. The design process of the antenna will be started all over again if the simulation did not satisfy the requirements of the desired antenna which is called an optimization of antenna parameters. The fabrication of the antenna is carried out after the desired antenna has been obtained. After the fabrication, the antenna’s return loss, bandwidth and radiation pattern is measured.
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Figure 1.1 Design flow diagram for E and H antenna Literature review
Measurement Design the antenna
Fabrication Simulation
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CHAPTER 2
LITERATURE REVIEW
An antenna or commonly known as an aerial is defined as “a means for radiating or receiving radio waves”, from the IEEE Standard Definitions of Terms for Antennas.
In other words, an antenna is taken as the transitional structure between free space and a guiding device. There is various types of antenna for example, wire antennas, aperture antennas, microstrip antennas, array antennas, reflector antennas and lens antennas [11]. The antenna is basically a transducer which converts electromagnetic energy in a cable into an electromagnetic radiated power in free space. Various characteristics of an antenna determine how efficient the conversion is performed. The antenna is expected to have as much energy as possible carried on as radiation and it should not be capable of consuming energy itself. It is important that the antenna concentrates its radiated energy as efficiently as possible in the required way. If so, either a wide coverage range or a reduced transmitting power can be achieved, until the range is exactly suit the one required [11].
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2.1 Fundamental Parameters of Antennas
The fundamental parameters of the antenna are necessary to describe the performance of the antennas. The radiation pattern of an antenna is a mathematical function or a graphical representation of the radiation properties of the antenna as a function of space coordinates. It can be determined in the far-field region and is represented as a function of the directional coordinates. The radiation properties include power flux intensity, radiation intensity, field strength, directivity phase or polarization.
In the other hand, the directivity of an antenna is defined as “the ratio of the radiation intensity in a given direction from the antenna to the radiation intensity averaged over all directions. The average radiation intensity is equal to the total power radiated by the antenna divided by 4π. If the direction is not specified, the direction of maximum radiation intensity is implied”. The directivity can be written as in equation (2.1) below rad o P U D
Dmax max
4
(2.1) where Do is the maximum directivity, Umax represents the maximum radiation intensity measured in Watt per unit solid angle, and Prad is the total radiated power measured in Watt (W) [11].
Another useful parameter that is used to describe an antenna performance is gain. The gain of an antenna is defined as
G . D (2.2) where indicates the efficiency of the antennas where is always less than the directivity. For most antenna types, the own loss is so low that G = D can be considered.
The bandwidth of an antenna is defined as “the range of frequencies within which the performance of the antenna, with respect to some characteristic, conforms to a specified standard”. For broadband antennas, the bandwidth is usually expressed as the ratio of the upper-to-lower frequencies of acceptable operation. Because the
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CHAPTER 1
INTRODUCTION
1.1 Introduction
A conventional microstrip patch antenna has been very popular due its numerous advantages such as low profile, light weight, and compatible with microwave integrated circuit but the major weakness is its narrow bandwidth [1-6]. The bandwidth of the conventional microstrip patch antenna is only about 11.2 MHz [7]. The E and H antenna is designed based on the character E and H itself. The purpose of this project is to design an antenna for broadband application that can operate with a wider bandwidth compared to conventional microstrip patch antenna. The broadband resonant can be obtained by proper selecting the structure of E and H. An end-loaded slot antenna can be used to reduce the length of a slot antenna without changing its resonant frequency.
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A novel H-shaped patch antenna is proved to have a smaller size, less number of modes, absence of harmonic resonance, and the provision of pure reactive impedances at its harmonic resonance, and the provision of pure reactive impedances at its harmonics that can result in increased transmitter efficiency [8].
In the other hand, a wide-band E-shaped patch antenna is introduced. Two parallel slots are incorporated into the patch of a microstrip antenna to expand it bandwidth. When two parallel slots are incorporated into the antenna patch, the bandwidth increases above 30% from the conventional microstrip patch antenna [9].
A novel wideband L-Probe fed inverted hybrid E-H shaped microstrip patch antenna (LIEH) covering the International Mobile Communications – 2000 (IMT-2000) band is designed that adopts contemporary techniques such as L-probe feeding, inverted patch structure with air-filled dielectric and slotted patch. The results is an antenna with an achievable bandwidth of 17.20% at 14 dB return loss (SWR=1.5) [10].
1.2 Objectives
The objectives of this project are to design an E and H shaped antenna that can operate at broadband frequencies. The suitable width and length of the desired antenna will be determine by proper selecting the E and H structure that will satisfy the broadband resonant. The return loss of the antenna is expected to be less than -10 dB and the bandwidth of the antenna is wider than the bandwidth of the conventional microstrip patch antenna.
1.3 Problem Statement
A conventional microstrip patch antenna is known to have many advantages but the major weakness is its narrow bandwidth. A bandwidth is the difference between the
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highest frequency and the lowest frequency. An antenna that has a wider bandwidth is suitable for broadband application. In addition, the antenna with smaller size is an advantage [8].
1.4 Scope
The scope of this project is to design an E and H antenna with suitable width, W and length, L for broadband application. The simulation of return loss and bandwidth of the antenna is carried out using Computer Simulation Technology (CST) Microwave Studio. The optimization of H antenna involved its impedance ratio and resonator length. However, the optimization of E antenna involved its slot position and slot length. Next, after it satisfy the require condition, the antenna is fabricated on FR4 board using chemical etching technique. The antenna’s performance is measured such as its bandwidth, gain, directivity, return loss, radiation pattern and etc.
1.5 Methodology
Figure 1 shows the design flow diagram for E and H antenna design. Firstly, to obtain enough information about this project, a literature review is carried out from journals and books. After that, the design process started with calculation for antenna parameters for example the width and length, by referring to the method that has been reviewed. Then, the simulation of return loss, bandwidth, radiation pattern and etc is carried out. The design process of the antenna will be started all over again if the simulation did not satisfy the requirements of the desired antenna which is called an optimization of antenna parameters. The fabrication of the antenna is carried out after the desired antenna has been obtained. After the fabrication, the antenna’s return loss, bandwidth and radiation pattern is measured.
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Figure 1.1 Design flow diagram for E and H antenna Literature review
Measurement Design the antenna
Fabrication Simulation
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CHAPTER 2
LITERATURE REVIEW
An antenna or commonly known as an aerial is defined as “a means for radiating or receiving radio waves”, from the IEEE Standard Definitions of Terms for Antennas. In other words, an antenna is taken as the transitional structure between free space and a guiding device. There is various types of antenna for example, wire antennas, aperture antennas, microstrip antennas, array antennas, reflector antennas and lens antennas [11]. The antenna is basically a transducer which converts electromagnetic energy in a cable into an electromagnetic radiated power in free space. Various characteristics of an antenna determine how efficient the conversion is performed. The antenna is expected to have as much energy as possible carried on as radiation and it should not be capable of consuming energy itself. It is important that the antenna concentrates its radiated energy as efficiently as possible in the required way. If so, either a wide coverage range or a reduced transmitting power can be achieved, until the range is exactly suit the one required [11].
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2.1 Fundamental Parameters of Antennas
The fundamental parameters of the antenna are necessary to describe the performance of the antennas. The radiation pattern of an antenna is a mathematical function or a graphical representation of the radiation properties of the antenna as a function of space coordinates. It can be determined in the far-field region and is represented as a function of the directional coordinates. The radiation properties include power flux intensity, radiation intensity, field strength, directivity phase or polarization.
In the other hand, the directivity of an antenna is defined as “the ratio of the radiation intensity in a given direction from the antenna to the radiation intensity averaged over all directions. The average radiation intensity is equal to the total power radiated by the antenna divided by 4π. If the direction is not specified, the direction of maximum radiation intensity is implied”. The directivity can be written as in equation (2.1) below rad o P U D
Dmax max
4
(2.1) where Do is the maximum directivity, Umax represents the maximum radiation intensity
measured in Watt per unit solid angle, and Prad is the total radiated power measured in
Watt (W) [11].
Another useful parameter that is used to describe an antenna performance is gain. The gain of an antenna is defined as
G . D (2.2) where indicates the efficiency of the antennas where is always less than the directivity. For most antenna types, the own loss is so low that G = D can be considered.
The bandwidth of an antenna is defined as “the range of frequencies within which the performance of the antenna, with respect to some characteristic, conforms to a specified standard”. For broadband antennas, the bandwidth is usually expressed as the ratio of the upper-to-lower frequencies of acceptable operation. Because the