gain and radiation of antenna using amc

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GAIN AND RADIATION IMPROVEMENT OF DUAL

SLOTTED PATCH ANTENNA USING ARTIFICIAL

MAGNETIC CONDUCTOR

A Thesis Submitted inPartial Fulfilment of the Requirements for the Degree of

Bachelor of Technology

BY

Abhishek Anand (BT12EC009)

Sumit Tiwari (BT12EC016)

Under the Supervision of

Mr. Anumoy Ghosh (Asst. Prof)

Department of Electronics and Communication Engg.

NATIONAL INSTITUTE OF TECHNOLOGY

MIZORAM (2016)


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DECLARATIONThesis Title:Gain and radiation improvement of dual slotted patch antenna using

artificial magnetic conductorDegree for which the Thesis is submitted: Bachelor of technology

We declare that the presented thesis represents largely our own ideas and work in my

own words. Where others ideas or words have been included, we have adequately cited

and listed in the reference materials. The thesis has been prepared without resorting to

plagiarism. We have adhered to all principles of academic honesty and integrity. No

falsified or fabricated data have been presented in the thesis. We understand that any

violation of the above will cause for disciplinary action by the Institute, including

revoking the conferred degree, if conferred, and can also evoke penal action from the

sources which have not been properly cited or from whom proper permission has not

been taken.

Name of the Students: Signature

1.Abhishek Anand (BT12EC009)

2. Sumit Tiwari (BT12EC016)


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CERTIFICATE

It is certified that the work contained in this thesis entitled Gain and radiationimprovement of dual slotted patch antenna using artificial magnetic conductorsubmitted by ABHISHEK ANAND (BT12EC009) and SUMIT TIWARI (BT12EC016)for the award of B.Tech is absolutely based on their own work carried out under my

supervision and that this work/thesis has not been submitted elsewhere for any

degree/diploma.

Mr. Anumoy Ghosh

(Assistant Professor)

Electronics and Communication

Engineering


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ACKNOWLEDGEMENTOn the very outset of this project we would like to extend our sincere and heartfelt

obligation towards all the personage who has helped us in this endeavour. Without their

active guidance, help cooperation and encouragement, we could not have madeheadway in the project.

First and foremost we would like to express our sincere gratitude to our guide, Mr.

Anumoy Ghosh (Assistant Professor) Department of Electronics and

Communication engineeringwe were privileged to experience a sustained enthusiastic

and involved interest from his side. This fuelled our enthusiasm even further and

encouraged us to boldly step into what was totally unexplored expanse before us. His

guidance and constant supervision as well as for providing necessary information

regarding the project and also his support has helped us in completing the project.

We are also indebted to a number of friends and well-wishers who extended their

cooperation and help in the preparation of the project. We once again put our sincere

thanks to everyone for their constant support and well wishes.


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Contents

Nomenclature Page No

List of Figures i

List of Tables ii

Chapter 1 Introduction to antennas 011.1 Antenna parameters 01

Chapter 2 Microstrip patch antennas 04

2.1 Microstrip Patch Antennas 04

2.2 Advantages and Disadvantages of Patch Antennas 07

2.3 Feed Techniques 07

2.3.1 Microstrip Line Feed 07

2.3.2 Coaxial Feed 08

2.3.3 Aperture Coupled Feed 09

2.3.4 Proximity Coupled Feed 10

2.4 Methods of Analysis 11

2.4.1 Transmission Line Model 11

2.4.2 Cavity Model 13

Chapter 3 Design and Simulation of Micrsostrip Patch Antennas

3.1 ANSYS HFSS 15

3.2 Antenna design 15

3.3 Dual slotted patch antenna 17

3.4 Radiation pattern 18

Chapter 4 Gain enhancement of antenna using AMC

4.1 Artificial magnetic conductor (AMC) 22

4.1.1Frequency selective surfaces 22

4.2 AMC as an FSS band gap 24

4.3 AMC Design 25

4.4 Use of AMC with antenna with patch antenna 26

Chapter 5:Improvement in radiation of antenna using AMC

5.1 Antenna design 28

5.2 Radiation pattern 29

5.3 Result 31

Chapter 6 Conclusion and Future Prospects 32

References
https://en.wikipedia.org/wiki/Frequency_selective_surfaceshttps://en.wikipedia.org/wiki/Frequency_selective_surfaces


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LIST OF FIGURES: PAGE NO

Figure 2.1:A Typical Microstrip Patch Antenna 04Figure 2.2 Typical patch shapes 05

Figure 2.3 Microstrip antenna and coordinate system 06

Figure 2.4: Typical radiation pattern of a square patch 08

Figure 2.5: Coaxial Feed 09

Figure 2.6: Aperture Feed 09

Figure 2.7: Proximity Coupled Feed 10

Figure 2.8:Microstrip Line 11Figure2.9Electric Field Lines 11Figure2.10Top View of Antenna 12Figure2.11Side View of Antenna 13Figure 3.1 microstrip patch antenna 15

Figure 3.2: S11 graph of microstrip patch antenna 16Figure 3.3 dual slotted patch antenna 17

Figure 3.4: S11 graph of dual slotted microstrip patch antenna 17

Figure 3.5: Radiation lobes and beamwidths of an antenna pattern 18

Figure 3.6: Omnidirectional antenna pattern 19

Figure 3.7: field regions of an antenna 19

Figure 3.8: radiation pattern of E plane at 4.144Ghz 20

Figure 3.9: radiation pattern of H plane at 4.144Ghz 20

Figure 3.10: radiation pattern of E plane at 6.4684Ghz 21

Figure 3.11: radiation pattern of H plane at 6.468Ghz 21

Figure 4.1:top image represents circuit board and bottom metal plate lattice 22

Figure 4.2: AMC unit cell 25

Figure 4.3: s11 graph of AMC cell 26

Figure 4.4: Complete AMC design 26

Figure 4.5: dual slotted patch antenna using AMC 27

Figure 4.6: S11 graph of dual slotted microstrip patch antenna using AMC 27

Figure 5.1: dual slotted patch antenna using AMC downwards 28

Figure 5.2S11 graph of dual slotted microstrip patch antenna using AMC 29

Figure 5.3: radiation pattern of E plane at 4.144 GHz 29

Figure 5.4: radiation pattern of H plane at 4.144 GHz 30

Figure 5.5: radiation pattern of E plane at 6.512 GHz 30

Figure 5.2: radiation pattern of H plane at 6.512 GHz 30

LIST OF TABLES: PAGE NO

Table 3.1calculated parameters of antenna 21Table 4.1calculated parameters of antenna using AMC above patch 27Table5.1calculated parameters of antenna using AMC below patch 31


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ABSTRACT

In this project, finite element method based ANSYS HFSS software is used to design a

dual slotted Microstrip Patch Antenna using artificial magnetic conductor with

enhanced gain and improved radiation. This thesis aims at improvement in gain andradiation of microstrip patch antenna using AMC. At first extensive study of microstrip

patch antenna along with various feeding techniques has been carried out. Finally novel

dual band patch antenna has been designed using slot on radiating surface of antennas.

The theory of artificial magnetic conductor and its use in antenna has been presented

subsequently a dual band AMC has been designed and used in conjunction with

designed dual band antenna I various orientations.

Different orientations have been investigated for enhancement of gain and directivity of

antenna at both resonant frequencies also the AMC has been used to reduce the back

lobe radiation significantly and thus increasing the front to back ratio of radiation

pattern in both E and H planes at both the resonant frequencies hence improvement of

radiation pattern is also achieved. The proposed techniques can be used to design

antennas with high gain and good radiation pattern suitable for practical wireless

applications.


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Chapter

1

Introduction to Antennas:

1.1 Antenna parameters

TheIEEE Standard Definitions of Terms for Antennas (IEEE Std 1451983) defines theantenna or aerial as a means for radiating or receiving radio waves.An antenna is anelectrical conductor or system of conductors [1]

Transmitter - Radiates electromagnetic energy into space

Receiver - Collects electromagnetic energy from space

The major parameters associated ith an antenna are defined in the following sections.

1.1 .1Antenna Gain

Gain is a measure of the ability of the antenna to direct the input power into radiation in

a particular direction and is measured at the peak radiation intensity. Consider the power

density radiated by an isotropic antenna with input power P0at a distance Rwhich is

given by S = P0/4R2. An isotropic antenna radiates equally in all directions, and itsradiated power density S is found by dividing the radiated power by the area of the

sphere 4R2. An isotropic radiator is considered to be 100% efficient. The gain of anactual antenna increases the power density in the direction of the peak radiation :[1]


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1.1.2 Antenna EfficiencyThe surface integral of the radiation intensity over the radiation sphere divided by the

input power P0 is a measure of the relative power radiated by the antenna, or the

antenna efficiency.

Where Pr is the radiated power. Material losses in the antenna or reflected power due to

poor impedance match reduce the radiated power.

1.1.3 Effective Area

Antennas capture power from passing waves and deliver some of it to the terminals.Given the power density of the incident wave and the effective area of the antenna, the

power delivered to the terminals is the product.

For an aperture antenna such as a horn, parabolic reflector, or flat-plate array, effective

area is physical area multiplied by aperture efficiency. In general, losses due to material,

distribution, and mismatch reduce the ratio of the effective area to the physical area.

Typical estimated aperture efficiency for a parabolic reflector is 55%. Even antennas

with infinitesimal physical areas, such as dipoles, have effective areas because they

remove power from passing waves.

1.1.4 DirectivityDirectivity is a measure of the concentration of radiation in the direction of the

maximum.

Directivity and gain differ only by the efficiency, but directivity is easily estimated from

patterns. Gaindirectivity times efficiencymust be measured. The average radiationintensity can be found from a surface integral over the radiation sphere of the radiation

intensity divided by 4, the area of the sphere in steradians.


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1.1.5 Path Loss

We combine the gain of the transmitting antenna with the effective area of the receiving

antenna to determine delivered power and path loss. The power density at the receiving

antenna is given by equation 1.2 and the received power is given by equation 1.4. By

combining the two, we obtain the path loss as given below.

Antenna 1 transmits, and antenna 2 receives. If the materials in the antennas are linear

and isotropic, the transmitting and receiving patterns are identical. When we consider

antenna 2 as the transmitting antenna and antenna 1 as the receiving antenna, the path

loss is

We make quick evaluations of path loss for various units of distanceR and for

frequencyf in megahertz using the formula

1.1.8 Return LossIt is a parameter which indicates the amount of power that is lost to the load and doesnot return as a reflection. Hence the RL is a parameter to indicate how well the

matching between the transmitter and antenna has taken place. Simply put it is the S11

of an antenna. A graph of s11 of an antenna vs frequency is called its return loss curve.


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Chapter

2

Microstrip patch antennas

2.1 Microstrip Patch Antennas:Microstrip antennas are planar resonant cavities that leak from their edges and radiate.

Printed circuit techniques can be used to etch the antennas on soft substrates to produce

low-cost and repeatable antennas in a low profile. The antennas fabricated on compliant

substrates withstand tremendous shock and vibration environments. Manufacturers for

mobile communication base stations often fabricate these antennas directly in sheet

metal and mount them on dielectric posts or foam in a variety of ways to eliminate the

cost of substrates and etching. This also eliminates the problem of radiation from

surface waves excited in a thick dielectric substrate used to increase bandwidth.

In its most basic form, a Microstrip patch antenna consists of a radiating patch on one

side of a dielectric substrate which has a ground plane on the other side as shown in

Figure. The patch is generally made of conducting material such as copper or gold and

can take any possible shape. The radiating patch and the feed lines are usually photo

etched on the dielectric substrate. Arrays of antennas can be photoetched on the

substrate, along with their feeding networks. Microstrip circuits make a wide variety ofantennas possible through the use of the simple photoetching techniques.


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FIGURE 2.1A Typical Microstrip Patch Antenna

In order to simplify analysis and performance prediction, the patch is generally square,

rectangular, circular, triangular, and elliptical or some other common shape as shown in

Figure 2. For a rectangular patch, the length L of the patch is usually 0.3333o

< L

gain and radiation of antenna using amc

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