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Microwave Probe Inspired By Metamaterial 2014
1 | P a g e
CHAPTER 1
INTRODUCTION
1.1 Introduction
This research concerns about developing microwave probe inspired by MTMs
(5.725 5.875 GHz). The term of metamaterial was synthesized by Rodger M. Walser,
University of Texas at Austin, in 1999, which was originally defined as Macroscopic
composites having a synthetic, three-dimensional, periodic cellular architecture designed to
produce an optimized combination, not available in nature, of two or more responses to
specific excitation [1, 2]. The metamaterial is defined as a material which gains its
properties from its structure rather than directly from its composition [2].
The above definitions reflect certain natures of metamaterial, but not all. Actually,
The term metamaterials"(MTMs) had been originally employed to describe any artificial
(engineered) structure possessing effective electromagnetic properties not encountered
among natural materials. The unusual properties and ability to control the electromagnetic
field enabled by MTMs
MTMs gain their properties not from their composition, but from their exactingly
designed structures. The permittivity, permeability and conductivity of a material
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characterize its ability to interact with electromagnetic fields; the magnitudes of these three
quantities are restricted mostly to positive values.
However, MTMs is material with simultaneous negative permittivity () and
negative permeability () would also have a real refractive index, meaning that light waves
could propagate through the material, but would behave as though its refractive index were
negative. The negative refractive index means the wave associated with the antenna is bent
to a sharper angle. As Veselago theorized, if both parameters are negative, then a negative
coefficient must be used.
Beside from that, the probe also plays an important role in this project. Common
types of probes such as waveguide based or coaxial line based probe often operate at 5.725
5.875 GHz or 6GHz to achieve a resolution in the order of millimeters. The high
operation frequency is due to the relatively weak concentration of evanescent fields in the
close proximity of the opening. On the other hand evanescent microwave probes (EMPs)
with sharp tips, such as microstrip resonators utilizing wire tips or loops, cavity resonators
with sharpened tips, and dielectric waveguide sharpened at the end, provide higher
resolutions, and are applied to a wide range of materials.
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1.2 Problem Statement
Too fulfill this project, type of MTMs need to figure out because every size, shape
and design will give impact to the result performance. MTMs have it own classification,
each type have their characteristic need to consider for this project.
1.3 Objectives
The main objective of this project is to design MTMs- split-ring resonator (SRR).
The main objectives for this project are:
1. To analyze the MTMs Split-Ring Resonator.
2. To design and simulate Split Ring Resonance (one port and two ports) using
Computer Simulation Technology (CST).
3. To fabricate design of Split Ring Resonator 1 and 2 ports.
4. To improve efficiency-bandwidth performance of the design by using MTMs.
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1.4 Project Organization
TOPIC DESCRIPTION
CHAPTER 1
Introduction
Introduction to Metamaterials (MTMs)
Objectives and problem statement of the project.
CHAPTER 2
Literature
Review
Discusses the theoretical concepts behind MTMs and design
that need to be considering achieving it.
CHAPTER 3
Methodology
Design of concept will be explains in this chapter.
CHAPTER 4
Result and
Discussion
Shows the results that collected from analytical results and
simulation representation. Made some hypothesis according
to the results.
CHAPTER 5
Conclusion
States the conclusion can be made according to the overall
system that was design in the simulation and also state future
work.
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CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
In this chapter will explain about the project based on previous project as a
reference for better understanding. It will discuss some of the issues that are the most
important in microwave probe inspired by MTMs.
2.2 Metamaterials (MTMs)
MTMs predicated contrivances have received a very vigorous interest in the last
years since the experimental demonstration of a negative refractive index effect.
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Figure 2.1: Metamaterial at atomic structure.
MTMs are artificial materials were introduced by Russian scientist Vesalago in the
year 1960 [3]. In contrast to conventional material, left handed MTMs is designed to
exhibit negative permeability and negative permittivity in the microwave frequency range
of interest. SRR was proposed by Pendry et al., is designed to exhibit negative permeability
[4] and thin wire structure is used to exhibit negative permittivity.
2.2.1 Metamaterial Clasification
The response of a system to the presence of Electromagnetic field is determined by
the properties of the materials involved. These properties are described by defining the
macroscopic parameters permittivity and permeability of these materials. By using
permittivity and permeability the classification of MTMs as follows, the medium
classification can be graphically illustrated as shown in figure 2.2
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Figure 2.2: MTMs Classification [3]
i. A medium with both permittivity and permeability greater than zero (e > 0, > 0)
are called as double positive (DPS) medium. Most occurring media (e.g. dielectrics)
fall under this designation.
ii. A medium with permittivity less than zero & permeability greater than zero (e < 0,
> 0) are called as Epsilon negative (ENG) medium. In certain frequency regimes
many plasmas exhibit this characteristics.
iii. A medium with both permittivity greater than zero & permeability less than zero (e
> 0, < 0) are called as Mu negative (MNG) medium. In certain frequency regimes
some gyrotropic material exhibits this characteristic.
iv. A medium with both permittivity & permeability less than zero (e < 0, < 0) are
called as Double negative (DNG) medium. This class of materials has only been
demonstrated with artificial constructs.
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2.2.1.1 Single Negative MTMs (SNG)
In single negative (SNG) MTMs either permittivity or permeability are negative,
but not both. Interesting experiments have been conducted by combining two SNG layers
into one MTMs. These effectively create another form of DNG MTMs. A slab of ENG
material and slab of MNG material have been joined to conduct wave reflection
experiments. This resulted in the exhibition of properties such as resonances, anomalous
tunneling, transparency, and zero reflection. Like DNG MTMs, SNGs are innately
dispersive, so their permittivity , permeability , and refraction index n, will alter with
changes in frequency.
2.2.1.2 Double Negative MTMs (DNG)
In double negative MTMs (DNG), both permittivity and permeability are
negative resulting in a negative index of refraction. DNGs are also referred to as negative
index MTMs (NIM).
2.2.1.3 Electromagnetic Band Gap (EBG)
Electromagnetic Band Gap (EBG) based on Frequency Selective Surfaces (FSS) is
one type of MTMs with electrical properties[5][6][7]. Application of truncated frequency
selective surface (FSS) appears as EBG technique. Frequency Selective Surfaces (FSS)
based MTMs have become an alternative to the fixed frequency MTMs.
2.2.1.4 Left-Handed Method (LHM)
The materials with simultaneously negative and are not found in nature. They
were artificially constructed in 2000.[2] Such man-made structures are called MTMs.
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Usually it is an assembly of cell elements. As long as the size and spacing between the
elements are much smaller than the electromagnetic wavelengths of interest, the incident
radiation cannot distinguish the collection of elements from a homogeneous material. The
idea behind making a left-handed MTMs (LHM) is to treat electric and magnetic
properties separately [7][8].
2.2.1.5 Split-Ring Resonator (SRR)
A split-ring resonator (SRR) is a component part of a negative index MTMs (NIM),
also known as double negative MTMs (DNG). They are also component parts of other
types of MTMs such as Single Negative MTMs (SNG). SRRs are also used for research
in terahertz MTMs, acoustic MTMs, and MTMs antennas [7][8]. SRRs are a pair of
concentric annular rings with splits in them at opposite ends. The rings are made of
nonmagnetic metal like copper and have small gap between them.
There are varieties of SRR structures have been reported in literature like square,
circular, triangular, omega, labyrinth resonator. MTMs are used for optical and microwave
applications such as filters, couplers, lenses, and switches etc.. Artificial MTMs structures
are also used in the antenna design to enhance the antenna performance.
The SRR exhibits a large magnetic dipole moment when excited by a magnetic field
directed along its axis. However, the SRR also exhibits an electric response that can be
quite large depending on the symmetry of the SRR and the orientation of the SRR with
respect to the electric component of the field. So, while the SRR medium can be considered
as having a predominantly magnetic response for certain orientations with respect to the
incident wave, it is generally the case that the SRR exhibits magneto electric coupling, and
hence a medium of SRRs arranged so as to break mirror symmetry about one of the axes
will exhibit bianisotropy.
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2.2.2 Resonant and Non-resonant MTMs
In the rapid design of MTMs, more specifically, the particle design, it is important to
choose the types of particles. Generally, MTMs are classified into two classes: resonant
and non-resonant MTMs. Both resonant and non-resonant MTMs had their own
advantages and disadvantages.[9][10]
Figure 2.3: The constitutive parameters (permeability) of a periodic structure whose
inclusion is SRR. (a) From the DrudeLorentz model under the static and quasi-static limits (above). (b) From the S-parameter retrieval under full-wave simulations (below).[10]
Figure 2.3(b) shows the material properties of a typical resonant MTMs composed of
SRR, as illustrated in the inset of Figure 2.1(a). From Figure 2.3(b), one clearly observes
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that both the permittivity and the permeability have a large dynamic range near the resonant
frequency. When the frequency changes a little bit, and vary a lot. In the other word,
when the size of SRR particle has a small change, the resonant frequency has a small shift,
which results in significant change of and . Hence one can realize large dynamic-range
material parameters using the resonant particle. This is the advantage of resonant MTMs.
However, one also notices from Figure 2.3(b) that and have a narrow bandwidth and
a large loss near the resonant frequency, which are disadvantages of resonant MTMs.
Figure 2.4: The effective constitutive parameters of a non-resonant MTMs whose inclusion is I-shaped.[10]
In fact, non-resonant MTMs have also resonant frequencies, but they are much higher.
Figure 2.4 demonstrates the constitutive parameters of a typical non-resonant MTMs
composed of I-shaped inclusion (see the inset of Fig. 2.4). It is clear that both and vary
slowly with respect to the frequency and have very small loss. Hence the broad bandwidth
and low loss are the big advantages of the non-resonant MTMs. On the other hand, when
the size of I-shaped particle has a small change, and have also small change. Hence one
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can only realize small dynamic-range material parameters using the non-resonant particle,
which is the disadvantage of non-resonant MTMs.[10]
2.2.3 Metamaterial Application
2.2.3.1 Metamaterial Antennas
MTMs antenna are a class of antennas which use MTMs to enhance or increase
performance of the system. The MTMs could enhance the radiated power of an antenna.
Materials which can attain negative magnetic permeability could possibly allow for
properties such as an electrically small antenna size, high directivity, and tunable
operational frequency, including an array system. Furthermore, MTMs based antennas can
demonstrate improved efficiency-bandwidth performance.
2.2.3.2 Superlens
A superlens uses MTMs to achieve resolution beyond the diffraction limit. The
diffraction limit is inherent in conventional optical devices or lenses.
2.2.3.3 Clocking Devices
MTMs are a basis for attempting to build a practical cloaking device. The cloak
deflects microwave beams so they flow around a hidden object inside with little
distortion, making it appear almost as if nothing were there at all. Such a device typically
involves surrounding the object to be cloaked with a shell which affects the passage of light
near it.
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2.2.3.4 Acoustic MTMs
Acoustic MTMs are artificially fabricated materials designed to control, direct, and
manipulate sound in the form of sonic, infrasonic, or ultrasonic waves, as these might occur
in gases, liquids, and solids.
2.2.3.5 Seismic MTMs
Seismic MTMs are MTMs which are designed to counteract the adverse effects of
seismic waves on manmade structures, which exist on or near the surface of the earth.
2.3 Feeding
The most four popular feeding techniques for microstrip patch antenna are coaxial
feeding, microstrip feeding, proximity feeding and aperture feeding.
2.3.1 Coaxial feeding
It is one of the basic techniques used in feeding microwave power. The coaxial
cable is connected to the antenna such that its outer conductor is attached to the ground
plane while the inner conductor is soldered to the metal patch [1, 11-12].
Figure 2.5: Coaxial feeding [1, 11-12]
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Coaxial feeding is simple to design, easy to fabricate, easy to match and have low
spurious radiation [11-12]. But coaxial feeding has the disadvantages of requiring high
soldering precision. There is difficulty in using coaxial feeding with an array since its need
a large number of solder joints. Coaxial feeding usually gives narrow bandwidth and when
a thick substrate is used a longer probe will be needed which increases the surface power
and feed inductance [11-13].
2.3.2 Microstrip feeding
In microstrip feed, the patch is fed by a microstrip line that is located on the same
plane as the patch. In this case both the feeding and the patch form one structure. Microstrip
feeding is simple to model, easy to match and easy to fabricate. It is also a good choice for
use in antenna-array feeding networks. However microstrip feed has the disadvantage of
narrow bandwidth and the introduction of coupling between the feeding line and the patch
which leads to spurious radiation and the required matching between the microstrip patch
and the 50 feeding line. Microstrip feed can be classified into 3 categories: direct feed,
inset feeding and gap-coupled.
Direct feed is where the feeding point is on one edge of the patch. As shown in
Figure 2.6. Direct feed needs a matching network between the feed line and the patch (such
as quarter wavelength transformer). The Quarter wave length transformer compensates the
impedance differences between the patch and the 50 feed line. The quarter wave length
transformer is calculated according to formulas found in [12, 16].
Figure 2.6: Direct microstrip feed line[12, 16]
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Inset feed is where the feeding point is inside the patch. The location of the feed is
the same that will be used for coaxial feed. The 50 feed line is surrounded with an air gap
till the feeding point as shown in Figure 2.7. The inset microstrip feeding technique is more
suitable for arrays feeding networks [11-13].
Gap-coupled is when the feeding line does not contact the patch; there is an air gap
between the 50 line and the patch as shown in Figure 2.8 .The antenna is fed by coupling
between the 50 feed line and the patch.
Figure 2.7: Inset microstrip feed line[12, 16]
Figure 2.8: Gap-coupled microstrip feed line[12, 16]
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2.3.3 Proximity coupled feeding
Proximity coupled feeding consists of two dielectric substrate layers. The microstrip
patch antenna is located on the top of the upper substrate and the microstrip feeding line is
located on the top of the lower substrate as shown in Figure 2.9. It is a non contacting feed
where the feeding is conducted through electromagnetic coupling that takes place between
the patch and the microstrip line. The two substrates parameters can be chosen different
than each other to enhance antenna performance [11, 13]. The proximity coupled feeding
reduces spurious radiation and increase bandwidth. However it needs precise alignment
between the 2 layers in multilayer fabrication.
Figure 2.9: Proximity coupled microstrip feeding[11, 13]
2.3.4 Aperture coupled feeding
Aperture coupled feeding consists of two substrate layers with common ground
plane in-between the two substrates , the microstrip patch antenna is on the top of the upper
substrate & the microstrip feeding line on the bottom of the lower substrate and there is a
slot cut in the ground plane as shown in Figure 2.10. The slot can be of any size or shape
and is used to enhance the antenna parameters. It is a non contacting feed; the feeding is
done through electromagnetic coupling between the patch and the microstrip line through
the slot in the ground plane. The two substrates parameters can be chosen different than
each other to enhance antenna performance [1-2, 11-13]. The aperture feeding reduces
spurious radiation. It also increases the antenna bandwidth, improves polarization purity
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and reduces cross-polarization. But it has the same difficulty of the aperture feeding which
is the multilayer fabrication.
Figure 2.10: Aperture coupled microstrip feed [1-2, 11-13]
2.4 Probe
A probe with a higher sensitivity practically means a higher accuracy for material
characterization schemes, or the ability to detect smaller or deeper objects for detection
schemes. Material characterization refers to the extraction of electrical and magnetic
properties of materials or investigation of physical or chemical properties of materials using
the electrical and magnetic properties. Object detection refers to detecting any geometrical
change in the vicinity of the probe. Which includes detecting objects placed within a
medium or detecting any change in the surface topology of objects.
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2.5 Material
A material is a piece of matter that is made up of a sea of periodically-arranged
atoms and molecules. All materials can be classified into two categories, conductors or
insulators (dielectrics). Conductors are materials that contain free charges (electrons) which
move with applied current, whereas dielectrics consist of bound positive and negative
charges that respond to electromagnetic fields by aligning charge pairs along the direction
of the applied field.
2.5.1 Dielectric Material
A dielectric material (dielectric for short) is an electrical insulator that can
be polarized by an applied electric field. When a dielectric is placed in an electric field,
electric charges do not flow through the material as they do in a conductor, but only slightly
shift from their average equilibrium positions causing dielectric polarization. Because of
dielectric polarization, positive charges are displaced toward the field and negative charges
shift in the opposite direction. This creates an internal electric field that reduces the overall
field within the dielectric itself. If a dielectric is composed of weakly bonded molecules,
those molecules not only become polarized, but also reorient so that their symmetry axis
aligns to the field.[1]
2.6 Resonator Frequency
A resonator is a device or system that exhibits resonance or resonant behavior, that
is, it naturally oscillates at some frequencies, called its resonant frequencies, with
greater amplitude than at others. The oscillations in a resonator can be
either electromagnetic or mechanical (including acoustic). Resonators are used to either
generate waves of specific frequencies or to select specific frequencies from a signal.
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2.7 Computer Simulation Technology (CST)
Computer Simulation Technology (CST) offers accurate, efficient computational
solutions for electromagnetic design and analysis. This software is user-friendly 3D EM
simulation software enables to choose the most appropriate method for the design and
optimization of devices operating in a wide range of frequencies.
The CST Microwave studio is a full-featured software package for electromagnetic
analysis and design in the high frequency range. It simplifies the process of inputting the
structure by providing a powerful solid 3D modeling front end. Strong graphic feedback
simplifies the definition of the device even further. After the component has been modeled,
a fully automatic meshing procedure is applied before a simulation engine is started.
2.8 Parameters Result Analysis
2.8.1 Gain
The power gain and the directivity properties of an antenna are the quantities, which
define the ability of the antenna to concentrate energy in a particular direction and give a
clear view of the antenna radiation performance. The gain of an antenna is a measure of the
ability of an antenna to concentrate power into a narrow angular region of space. 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 ratio between
the amounts of energy propagated in these directions compared to the energy that would be
propagated if the antenna were omni-directional is known as its gain.
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2.8.2 Bandwidth
Bandwidth is the range of frequency that the antenna will properly radiate or receive
energy effectively where the antenna meets a certain set of specification performance
criteria [9]. When antenna power drops to half (3 dB), the upper and lower exterminates of
these frequency have been reached and the antenna no longer performs. An antenna that
operates over a wide frequency range and still maintain satisfactory performance must
compensating circuits switched into the system to maintain the impedance matching.
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CHAPTER 3
METHODOLOGY
3.1 Introduction
This chapter focuses on the method used in this project implementation including a
description of the flow and process. All the relevant experiment, description and work
involve in this project are also discussed. The entire steps are represented by a flow chart
and other related materials that will be discuss further.
3.2 Design Process
Base on Figure 3.1, it shows flowchart to complete this project. The design process
must follow the flowchart. Microwave probe Inspired by Metamaterial project is started by
determining the specification of the antenna. Various of similarly project is been reviewed
to gain more understanding and improvement of the previous project
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Figure 3.1: Project Flow Chart
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3.3 Design Specification
Figure 3.2: Split-ring Design for 1 Port
Table 3.1: Design Specification for Split-ring Design 1 Port.
Specification Value
Substrate FR4
Copper (annealed) Thickness 0.035mm
Ground (width x high) 30mm x 30mm
Feeding Line (width x high) 0.95mm x 15mm
Small Ring Diameter 2.5mm
Big Ring Diameter 4.5mm
Ring Angle 340
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Figure 3.3: Split-ring Design for 2 Port
Table 3.2: Design Specification for Split-ring Design 2 Port
Specification Value
Substrate FR4
Copper (annealed) Thickness 0.035mm
Ground (width x high) 30mm x 30mm
Feeding Line (width x high) 0.95mm x 30mm
Small Ring Diameter 2.5mm
Big Ring Diameter 4.5mm
Ring Angle 340
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Table 3.3: Final Designs
Design 1 Design 2 Design3
Original
shape
After
fabricatio
n
Table 3.3 show design of split-ring resonator for 1 port and 2 ports. SRR is designed
on an FR4 substrate. Split-ring resonator structure is used to exhibit negative permeability.
Microstrip feed is given to both inner and outer rings of split-ring resonator. MTMs
characteristics have been verified by transmission and reflection coefficient of split-ring
resonator. Split-ring resonator structure also satisfies homogeneous condition.
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3.3.1 Feeding Line
A feed line is used to excite to radiate by direct or indirect contact. There are many
different methods of feeding and four most popular methods are microstrip line feed,
coaxial probe, aperture coupling and proximity coupling.
3.3.1.1 Microstrip Line Feeding
Microstrip line feed is one of the easier methods to fabricate as it is a just
conducting strip connecting to the patch and therefore can be consider as extension of
patch. It is simple to model and easy to match by controlling the inset position.
Figure 3.4: Standard microstrip feeding line geometry.
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3.3.2 Split-Ring Resonator (SRR) Design
A split-ring resonator (SRR) is an artificially produced structure common
to metamaterials. Split-ring resonator structure is used to exhibit negative permeability.
Their purpose is to produce the desired magnetic susceptibility (magnetic response) in
various types of metamaterials up to 200 terahertz. These media create the necessary strong
magnetic coupling to an applied electromagnetic field, not otherwise available in
conventional materials. For example, an effect such as negative permeability is produced
with a periodic array of split ring resonators. [1]
Figure 3.5: A split-ring resonator. The current, denoted by small letter i, is in the
clockwise direction.
The split ring resonator and the metamaterials itself are composite materials. Each
SRR has an individual tailored response to the electromagnetic field. However, the periodic
construction of many SRR cells is such that the electromagnetic wave interacts as if these
were homogeneous materials.
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3.4 Probe
Figure 3.6: SMA-Right angle probe
Right-angle bends in PC-board traces perform perfectly well in digital designs in
speeds as fast as 2 Gbps. In most digital designs, the right-angle bend is electrically smaller
than a rising edge. For example, the delay through a right-angle bend in an 8-mil-wide, 50
microstrip trace in FR-4 is on the order of 1 psec. Thats less than 1 percent of a 100-psec
rise time.
3.5 Fabrication Process
Fabrication process the design layout printing using Gerber tool and printed on the
PCB inkjet film. It has been printed as a negative layout for FR4 negative board. After
print, the ultraviolet (UV) film need to be stick on the FR4 board by using laminator. Then,
put the film that has been stick on the board into the UV exposure for 120 seconds. After
finish, the board need to be soak on the photoresist chemical to eliminates the UV film that
are not exposed to the UV light and it will show the design shape before the board go
through the etching process. At etching process all the unexposed copper will be removed
and left the copper of the design pattern. After etching process, the feed connector is been
soldered to the feeding line of the design.
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CHAPTER 4
RESULT AND DISCUSSION
4.1 Introduction
Chapter 4 discussed about the simulation result. There are three designs that have
been fabricated. The result for simulation using CST software will be discussed more detail
in this chapter. The result will be compared based on the on the return loss, input
impedance, axial ratio and VSWR.
4.2 Simulation Results and Discussion
Simulation is the process of measuring the antenna by using software to obtain the
behavior of design. The important parameters of design that should be measured are return
loss, voltage standing wave ratio (VSWR), input impedance, axial ratio, and radiation
pattern. These parameters should be at the right value to get the best design with high
performance. Other than that, the design size should be decreased.
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4.2.1 Return Loss
The perfect designs should have a return loss below than -10 dB. It will have a good
performance when the return loss of design is below than -10 dB. The perfect matching of
return loss it means when no power reflected back to the input. In this situation, the return
loss between split-ring resonator 1 port and split-ring resonator 2 port.
4.2.1.1 Split Ring Resonator 1Port
Figure 4.1 : Split Ring 1 Port
Figure 4.2: S-Parameter for Split Ring 1Port
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Based on Figure 4.1, it shows the design of split ring for 1 port and Figure 4.2 show
return loss for split-ring for 1 port. Also the resonant frequency is at 6 GHz at -18.841dB
which is above than -10 dB. This result shows the split ring design had achieved matching
circuit and fall at 6GHz.
4.2.1.2 Split Ring Resonator 2 Port
Figure 4.3: Split Ring 2Port (S1,1)
Figure 4.4: S-Parameter for Split Ring 2Port (S1,1)
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Based on Figure 4.4, it shows the return loss for split-ring for 2 port (S1,1). Also the
resonant frequency is at 6 GHz at -39.243dB which is above than -10 dB.
Figure 4.5: Split Ring 2Port (S2,1)
Figure 4.6: S-Parameter for Split Ring 2Port (S2,1)
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4.2.2 Input Impedance
Input impedance is measured by using Smith Chart. Good input impedance is near
with a value of 50 which is matched with the transmission line of 50 .
Figure 4.7: Input impedance for split-ring 1 port.
Figure 4.8: Input impedance for split-ring 2 port.
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Figure 4.7 it shows the input impedance value for split-ring 1 port is 62 Ohm while
figure 4.8 shows the value for split-ring 2 ports is 49 Ohm. Which mean from the
simulation result, design split-ring 1 port is better for input impedance value.
4.2.3 Voltage Standing Wave Ratio (VSWR)
VSWR is a function of the reflection coefficient, which describes the power
reflected from the design. The VSWR is always a real and positive number for design. The
smaller the VSWR is, the better the design is matched to the transmission line and the more
power is delivered to the design. The minimum VSWR is 1.0. In this case, no power is
reflected from the design which is ideal.
Figure 4.9: VSWR for Split-ring 1 port
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Figure 4.10: VSWR for Split-ring 2 port
Figure 4.9 show the VSWR for MTMs Split-ring 1 port is 1.2580 and 4.10 show
the VSWR result for MTMs Split-ring 2 port is 1.0220. Both of the value is below 2 which
means that both of this design is at the best performance.
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4.2.4 Radiation Pattern
4.2.4.1 Split Ring Resonator 1Port
Table 4.1: Radiation Pattern for Split-Ring Resonator 1 Port
Plane Phi Theta
E-Plane
H-Plane
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Table 4.1 shows radiation pattern of Split-Ring Resonator 1 Port. Based on the
result of simulation, the main lobe magnitude in E-plane (phi) for split-ring resonator is
9.5dBV/m.
4.2.4.2 Split Ring Resonator 2Port
Table 4.2: Radiation Pattern for Split-Ring Resonator 2 Port
Plane Phi Theta
E-Plane
H-Plane
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Table 4.2 shows radiation pattern of Split-Ring Resonator 2 Port. Based on the
result of simulation, the main lobe magnitude in E-plane (phi) for split-ring resonator is
2.6dBV/m.
4.2.5 Gain, Directivity and Efficiency
Gain is defined as the ratio of the power produced by the antenna from a far-field
source on the antennas beam axis to the power produced by a hypothetical lossless
isotropic antenna, which is equally sensitive to signals from all directions. Directivity
measures the power density the antenna radiates in the direction of its strongest emission,
versus the power density radiated by an ideal isotropic radiator radiating the same total
power. Efficiency is defined as the ratio of the total power radiated by an antenna to the net
power accepted by the antenna from the connected transmitter.
Table 4.3: Gain, directivity and efficiency of design
Design Gain (dB) Directivity (dBi) Efficiency (%)
Split-Ring 1Port 2.231 4.914 44.8
Split-Ring 2 Port 1.231 5.367 25
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CHAPTER 5
CONCLUSION
5.1 Introduction
This final chapter discusses about two important parts. The first part is about overall
summary of the project whether this project achieved the objective and for the second part
is about recommendation to improve the performance of the antenna for future work.
5.2 Summary
The MTMs field is a very challenging from all aspects, in this paper, the analysis
and design of MTMs Inspired by Microwave Probe were presented. Motivated by the
challenge of enhancing the penetration of MTMs-related applications into commercial
products, low cost, easily deployable MTMs structures were proposed. Such MTMs
structures were employed for the design of easily fabricated.
For this project, 3 designs of split ring resonator has been design, simulate and
fabricate. This design were simulate using CST and result that have to be seen are return
loss, input impedance, VSWR, radiation pattern and efficiency. From simulation results, the
best split-ring resonator design has return loss below than -10dB, input impedance equal to
50 Ohm and VSWR in range between value 1 to 2.
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At the end of this project, it can be concluded that the objective of this project is
achieved. The split-ring resonator 1 port were designed and operate at 6 GHz with return
loss of -18.841 dB, input impedance of 62 and VSWR equal to 1.2580 while split-ring
resonator 2 port with return loss of -39.243,imput impedance of 49 and VSWR equal to
1.0220.
5.4 Recommendation
Recommendation for the future work is to do the measurement for this design and
compare with simulation result, from there can be seen the difference between the both
result and therefore able to see whether the design is a good.
Apart from that, Antenna systems and communications electronics in satellites can
incorporate MTMs as well. The payload size is minimized, making it easier to launch a
smaller satellite, and less expensive to design and build it. Applications of MTMs also
include smaller security equipment and devices used by the military. So far, as of 2011,
engineers have been able to cloak one wavelength at a time, but have theorized on
applications of MTMs for improving the performance of wireless devices, memory
storage, and optical lenses.
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REFERENCES
[1] Weiglhofer,W.S., Lakhtakia, A.: Introduction to complex mediums for optics and
electromagnetics. SPIE Press, Bellingham, WA, USA (2003)
[2] http://en.wikipedia.org/wiki/Metamaterial
[3] Veselago, V.G. The electrodynamics of substance with simultaneously negative
values of and . Sov. Phys. Usp. 1968, 10, 509514.
[4] Pendry, J.B.; Holden, A.J.; Robbins, D.J.; Stewart, W.J. Magnetism from conductors
and enhanced nonlinear phenomena. IEEE Trans. Microw. Theory Tech. 1999, 47,
20752084.
[5] Shelby, R.A.; Smith, D.R.; Schultz, S. Experimental verification of a negative index
of refraction. Science 2001, 292, 7779.
[6] Pendry, J.B. Negative refraction makes a perfect lens. Phys. Rev. Lett. 2000, 85,
39663969.
[7] Jacob, Z.; Alekseyev, L.V.; Narimanov, E. Optical hyperlens: Far-field imaging
beyond the diffraction limit. Opt. Express 2006, 14, 82478256.
[8] Liu, Z.; Lee, H.; Xiong, Y.; Sun, C.; Zhang, X. Optical hyperlens magnifying sub-
diffraction-limitted object. Science 2007, 315, 16861687.
[9] Smolyaninov, I.I.; Hung, Y.J.; Davis, C.C. Magnifying superlens in the visible
frequency range. Science 2007, 315, 16991701.
[10] Tie Jun Cui, Ruopeng Liu and David R. Smith : Introduction to MTMs.
[11] J. L. Volakis, Antenna Engineering Handbook 4th edition, McGraw-Hill, 2007.
[12] A. Milligan, Modern Antenna Design 2nd edition, John Wiley & Son Inc, 2005.
[13] R. Garg, P. Bhartia, I. Bahl , A. Ittipiboon, Microstrip Antenna Design Handbook,
Arteck House, 2001.
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[14] C. A. Balanis, Antenna Theory Analysis and Design 3rd edition, John Wiley &
Sons, Inc., 2005.
[15] Y. T. Lo, S. W. Lee, Antenna Handbook, Van Nostrand Reinhold, 1993.
[16] A. Y. Simba, M. Yamamoto, T. Nojima, K. Itoh, Circularly Polarised Proximity-
Fed Microstrip Antenna with Polarisation Switching Ability, IET Microwaves
Antennas & Propagation, Vol.1, Issue. 3, 2007, pp. 658 665.
[17] Y.-L. Kuo, Kin-Lu Wong, A Circularly Polarized Microstrip Antenna with a
Photonic Band Gap Ground Plane, in proceedings of Microwave Conference,
AMPC, Asia-Pacific , vol. 2, 2001 , pp. 647-650.
[18] D. M. Pozar, Microwave Engineering 2nd edition, John Wiley & Son, Inc.1998
[19] D. R. Smith, W. J. Padilla, D. C. Vier, S. C. Nemat- Nasser, and S. Schultz.
Composite medium with simultaneously negative permeability and permittivity,
Phys. Rev. Lett., vol. 84, no. 18, pp. 41844187, May 2000.
[20] C. Caloz, T. Itoh. Electromagnetic Metamaterials: Transmission Line Theory and
Microwave Applications, Wiley-IEEE Press, 2006
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APPENDICES
Appendix A
Final Year Project Progress Gantt Chart Part 1
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Final Year Project Progress Gantt Chart Part 2
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Appendix B
Fabrication process
Print layout
design on the
PCB inkjet film.
Cut it according
to the design
size.
Prepare
FR4 board.
Stick the PCB
inkjet film on the
FR4 board.
Put it into the UV
exposure for 120
seconds.
Soak the board
with photoresist
chemical.
Soldier the
connector into it
feeding line.
Clean and cut
into it proper
shape.
Put it into etching
machine to
eliminate
unwanted copper.
Clean it.
Finally, finish fabrication
process and can continue
to measure with
VNA(Vector Network
Analyzer).
Recommended