microstrip antenna for television and radio receiver

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MICROSTRIP ANTENNA FOR TELEVISION AND RADIO RECEIVER

FAMMY FAISAL BIN RASAT

This project is submitted in partial fulfilment of

the requirements for the degree of Bachelor of Engineering with Honours (Electronics & Telecommunication Engineering)

Faculty of Engineering

UNIVERSITI MALAYSIA SARAWAK

2004

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ACKNOWLEDGEMENT

First of all, the author would like to thank his supervisor, Mr. Thelaha bin Masri for the guidance and encouragement throughout the duration of the project.

The author would also like to thank his friends for giving the author a great idea in order to produce a better thesis and also for being supportive. Last but not least, the author also would like to take this opportunity to thank his family and his special one for the support, guidance and unremitting encouragement.

Thank you so much.

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ABSTRAK

Thesis bertajuk Microstrip antenna for TV and Radio Receiver bermatlamat untuk dijadikan sebagai rujukan kepada mereka yang berhasrat untuk memperluaskan atau melanjutkan pengetahuan mereka tarhadap microstrip antenna. Projek ini lebih menekankan kepada penggunaan Rectangular Microstrip Patch Antenna yang merupakan

salah satu bentuk asas microstrip antenna untuk menggantikan dipole antenna yang masih digunakan oleh system TV dan radio sekarang.

Projek ini juga dijalankan untuk mengkaji samada single microstrip patch antenna mampu melaksanakan tugas sebagai antenna penerima bagi tv dan radio. Perisian Microwave Office 2001 versi 3.22 telah digunakan untuk menghasilkan Carta Smith, VSWR, S11 Magnitude dan Carta Impedance. Semua keputusan yang telah diperolehi dari eksperimen disusun dalam bentuk jadual.

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ABSTRACT

The "Microstrip Antenna for Television and Radio Receiver" aims to live up its title, as a useful reference for those who wish to extend their familiarity with microstrip

antenna. In this project, the author concentrate on investigating a single rectangular microstrip patch antenna, which is the basic shape of microstrip antenna to replace the dipole and monopole antenna that used by television and radio.

This project is also meant to determine whether the single rectangular microstrip patch antenna is capable to do its tasks as a TV and radio-receiving antenna. Microwave

Office 2001 version 3.22 simulation software was used to generate the Smith Chart, VSWR, S 11 Magnitude and Impedance Chart to determine the performance and efficiency of the antenna that was being design. All the results obtained from all the experiments are then tabulated in a tabular form.

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LIST OF FIGURES

Figures Pages

2.1 A Microstrip Transmission Line 2.2 Loop Antenna

2.3 Horn Antenna

5 12 12

2.4 Helical Antenna 13

2.5 Patch Antenna 14

2.6 Dipole Antenna

2.7 Monopole Antenna

2.8 Cross Section of Microstrip Patch Antenna 2.9 Basic Microstrip Antenna Shapes

3.1 Flow-Chart of Methodology Used IN This Project 3.2 MathCAD Work Sheet for Patch Size Calculation

15 15 16 17 20 22

3.3 Cell Calculator Work Sheet 23

3.4 Orientation of the Patch

3.5 Substrate Information Window 3.6 Dielectric Layers Window

3.7 Boundary Window

3.8 Ruler Option to Measure the Patch

4.1 Dimension of the Patch Antenna and the Position of the Port

24 25 26 27 28 30

4.2 VSWR Chart 31

4.3 Magnitude (graph 31

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4.4 Impedance Graph

4.5 VSWR Graph (Method 1: Simulation 1)

4.6 Impedance Graph (Method 1: Simulation 1) 4.7 Magnitude Graph (Method 1: Simulation 1) 4.8 VSWR Graph (Method 1: Simulation 2)

4.15 Impedance Graph (Method 1: Simulation 4) 4.16 Magnitude Graph (Method 1: Simulation 4)

4.17 Removal of a Portion of the Right Patch (Simulation 1) 4.18 VSWR Graph (Method 3: Simulation 1)

4.21 Removal of a Portion of the Left Patch (Simulation 1) 4.22 VSWR Graph (Method 3: Simulation 2)

4.25 Removal of the Left and Right Edges of the Patch (Method 3: Simulation 3)

426 VSWR Graph (Method 3" Simu! 2tinn 3)

32 34 34 35 35 36 36 37 37 38 38

39

39 41 42

42 43 43 44 44 45

45

nr

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5.1 VSWR Graph (Optimum Design)

5.2 Impedance Graph (Optimum Design) 5.3 Magnitude Graph (Optimum Design)

5.4 Smith Chart (Optimum Design)

5.5 Radiation Pattern (Optimum Design)

46 47 50 51 51 52 52

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CHAPTER I

INTRODUCTION

1.1 Background

Antennas are the main component in the radar or communication system. In electromagnetic system, antennas play an important role where the antenna is a structure between the system and free space. In other word, an antenna is a component that converts a wave propagating on transmission line to a plane wave propagating in free space (transmission), or vice versa (reception) [1]. An antenna may be a part of a transmitting or receiving system which is designed to radiated or receiving electromagnetic waves, to or from the free space [3].

Antennas are widely used in the telecommunication systems such as television and radio reception to radar systems such as military surveillance, aviation navigation. The most important aspect in the designing process of an antenna is to produce a good quality of antennas that have a high efficiency, low loss and matching impedance besides it must suit its applications.

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1.2 Basic Types of Antennas

The quality and how antennas operate are very dependent on its geometry that refers to its physical structure. Furthermore, its orientation diversifies the characteristics of typical antennas. Nowadays, there are wide varieties of antenna types and geometries being developed. Some examples of these antennas are stated below [1]:

i) Wire antennas are the simplest types of antennas, and most of the earliest antennas (e. g., as used by Hertz and Marconi) were of this type. It is easy to fabricate, easy to feed and are lightweight.

ii) Rod antennas. The diameter of the rod is significant. These antennas include whip antennas and dipoles of all descriptions.

iii) Reflector antennas. It achieves a high gain by focusing the radiation from a small feed antenna with an electrically large reflector. They are relatively easy to

fabricate and are rugged, but can be large and impractical.

iv) Aperture antennas are often just flared sections of waveguide, or even open-ended waveguides. Aperture antennas are most commonly used at microwave frequencies and have moderate gains.

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v) Printed antennas are relatively new type of antenna comprising printed conductors on a microstrip or similar type of substrate. This makes them compatible with planar microwave circuit technology.

1.3 Objectives

The microstrip patch antenna has become more familiar to reseachers due to its versatile characteristics. Researchers have developed many shapes and types of microstrip patch antennas for different types of applications such as in aerospace and GPS. The use of microstrip patch antenna in TV and radio receiption is still new. This encourages the author

to choose this project where the author can design and determined the uses of microstrip patch antenna in TV and radio receiption. The main objectives of this project are as

follows:

i) To design and simulate a single rectangular microstrip patch antenna for radio and television receiver by using Microwave Office 2001.

ii) To learn more about the specific characteristic and operation of microstrip patch antenna, and also the various parameters involved in designing the antenna.

iii) To learn more on how to design an antenna using software called Microwave Office 2001.

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1.4 Project Overview

There are many types and shapes of microstrip patch antenna that are available nowadays such as single rectangular, round, triangle, coupled and array microstrip patch

antenna and some other more. As a start, in this project titled Microstrip Antenna for Television and Radio Receiver, the author determined the characteristics of single rectangular microstrip patch antenna for a television and radio antenna.

The frequency range used in designing the single rectangular microstrip patch antenna is from 80-600MHz whereby the antenna can receive the frequencies for radio and television at the same time. The frequency range for radio and TV channels in Malaysia

are:

Table 1.1 Frequencies Ranges for Radio and TV in Malaysia

Channels Frequency Range

Radio (FM) 87.75 - 108 MHz

TV I (VHF7) 174

- 180 MHz

TV2 (VHF10) 192

- 198 MHz

TV3 (VHF12) 204

- 210 MHz

NTV7 (UHF27) 548-554 MHz

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The single rectangular microstrip antenna is expected to receive the television and radio frequencies at the same time, that mean that it can accommodate all the frequencies for radio and television. This project is to determine whether the single rectangular microstrip patch antenna is suitable to be used as a TV and radio-receiving antenna and at the same time to look for the best design that can produce an optimum result which means that the antenna can receive the frequencies for TV and radio receiption.

MicroWave Office 2001 simulation software was used to determine the exact shape of the antenna. By using this software, we can generate the Smith's Chart, S 11 magnitude and Impedance Chart and VSWR.

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CHAPTER 2

LITERATURE REVIEW

2.1 Microstrip Transmission Line

A microstrip transmission line consists of a flat conducting strip suspended above a ground plane. The conducting strip is supported by a dielectric substrate and due to its open structure; the electromagnetic field is not confined to the solid dielectric. The conducting

strip is normally manufactured by etching copper-clad material using photographic techniques. An example of a microstrip transmission line is shown in Figure 2.1. [2]

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. -... T :., fll Fjrr,

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2.2 Dielectric Substrate

There are a various range of substrate materials is available in the market, which manufactured by the microwave substrate manufacturers such as Duriod, Polyguide, Rexolite, 3M and many others. Different manufacturers produce different substrates with values of substrate relative permitivity, loss tangent and thickness, varied with each other.

Substrate choice and evaluation are an essential part of the design procedure. Many substrate properties need to be considered such as the dielectric constant, loss tangent and the variation with temperature and frequency, homogeneity, isotropicity, thermal coefficient and temperature range are all important and to be considered in choosing the desired dielectric substrate. [4]

2.2.1 Dielectric Constant, Er

A range of substrates usually has various dielectric constants. The dielectric constant is the relative permittivity (Cr) of a material and it is usually dimensionless and always greater than 1. A dielectric constant of "1" is equivalent to the permittivity of a vacuum which has the lowest possible permittivity.

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The higher the permittivity especially referring to a high permittivity substrates, the more the energy will be reflected inside the antenna before leaving it and the more inferior and narrow-banded the antenna will get. [3]

2.3 Field Pattern of Microstrip Transmission Line

As known, the dielectric presence in the substrate does not fill the air region above the strip, which complicates the radiation behavior of microstrip line. Microstrip lines have some characteristic where the field lines in the dielectric region, usually concentrated between the strip conductor and the ground plane and there are some fraction occurs in the air region above the substrate.

The field consists of magnetic field and electric field, which go partly through air and partly through dielectric.

2.4 Definition of Important Antenna Parameters

2.4.1 Bandwidth

The bandwidth in antenna is best known as the ability of the antenna to operate and perform well over a range of frequency. Therefore, the goal must be to make it resonant in the middle of that hand. The ^term that ;c ^imnnrnnt he"- ^;c ^ond. ^{i ith} ^{?:, ý.} ^--I, ^bJ

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your antenna works well over. One method of judging how well (efficiently) your antenna is working is by measuring VSWR. [3]

The bandwidth can be increase by reducing the impedance mismatch or matching the networks of the antenna.

2.4.2 Voltage Standing Wave Ratio

VSWR is a measure of impedance mismatch between the transmission line and its load. The higher the VSWR, the greater the mismatch is. The minimum VSWR, i. e., that which corresponds to a perfect impedance match, is unity.

The combination of the original wave traveling down the coaxial cable (towards the antenna or opposite during receive) and the reflecting wave is called a standing wave. The ratio of the two above described waves is known as the Standing Wave Ratio. [3]

2.4.3 Efficiency

Efficiency (ß) is a figure showing the ratio of the total radiated power (Pr) to the total input power (Pa). Efficiency has no unit and the ideal figure is 1.

}0 = Pr i Pa [3]

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In real life a figure of 75% is very good while 50% is acceptable. It is essential to know how the measurement was performed before comparing figures from different manufacturers: was a matching network used? Was the measuring point as close to the

antenna as possible or was the transmission line included? Often, the figure for efficiency will dramatically decrease when the antenna is built into a device. [3]

2.4.4 Return Loss

This is basically the same thing as VSWR. If the antenna absorbs 50 % of the signal and 50 % is reflected back, we say that the Return Loss is -3dB. A very good antenna might have a value of -10dB (90 % absorbed & 10 % reflected).

When studying a graph showing Return LossNSWR, a deep and wide dip of the curve is good since this shows an antenna with good bandwidth (spreadband).

Consequently, the narrower the dip is, the bigger risk that also desired channels will be reflected away (narrow band). [3]

2.4.5 Polarization

The position and direction of the electric field with reference to the earth's surface (the ground) determines wave polarization. In general, the electric field is the same plane as the antenna's radiator.

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Horizontal polarization is where the electric field is parallel to the ground.

Meanwhile, vertical polarization is where the electric field is perpendicular to the ground.

There is one special polarization known as Circular polarization. As the wave travels it spins, covering every possible angle. It can either be right-handed or left-handed circular polarization depending on which way it's spinning. Take note that small antennas have no

clear polarization. [3]

2.4.6 Impedance

An antenna consists of a driving-point impedance to the source or load to which it is connected, and here where the impedance mismatches occurs. The mismatch degrades antenna performance and is dependent on the external circuitry that is connected to the antenna. [I ]

2.4.7 Radiation Pattern

The power radiated by an antenna is a function of angular position and radial distance from the antenna. The variation of power density with angular position is determined by the type and design of the antenna. This can be graphically represented as a radiation pattern plot. The transmitting and receiving pattern of an antenna are identical if the antenna contains no nonreciprocal material or components. [1]

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2.5 Antenna Types

There are many types of telecommunications devices and due to this, a suitable antenna for diffrerent devices and applications are needed. Nowadays, researchers have developed various types of antenna with different charatceristics and used for different applications but still with the same goal that is as a receiving and transmiting elements. In the market nowadays, we can found many antennas with different shapes and design. Some of the antennas available are shown briefly after this.

2.5.1 Loop Antenna

The loop antenna consist of a simple loop of wire with a specific radius a. The radius is small enough in comparison to a wavelength that the current can be assumed constant around its circumference. The loop antenna can be in any shape, with the same

field being produced provided the area enclosed by the loop is held constant. The loop antenna usually use as a compact receiving antennas, eg. in pagers. Below is an example of

loop antenna shown in Figure 2.2. [6]

Figure 2.2 Loop Antenna [6]