Mr. K.H.Murali



-680085267335 VARDHAMAN COLLEGE OF ENGINEERING (AUTONOMOUS)Shamshabad, Hyderabad - 501218 Department of Electronics and Communication Engineering CERTIFICATEThis is to certify that the mini project report work entitled “A DESIGN OF U-SHAPED SLOT ANTENNA WITH BROADBAND DUAL CIRCULARLY POLARIZED RADIATION” carried out by Mr.Charla Rajdeep Reddy, Roll Number 15881A0409, Mr.Mamidi Adharsh Bharat, Roll Number 15881A0430, Mr.Rottela Ramesh ,Roll Number 16885A0409 submitted to the department of Electronics and Communication Engineering, in partial fulfillment of the requirements for the award of degree of Bachelor of Technology in Electronics and Communication Engineering during the year 2015 – 2019.Name & Signature of the Name & Signature of the Supervisor HOD Mr. K.H.Murali Prof.Y.PandurangaiahAssistant Professor Head of ECE A Mini Project Report on A DESIGN OF U-SHAPED SLOT ANTENNA WITH BROADBAND DUAL CIRCULARLY POLARIZED RADIATION Submitted in the Partial Fulfillment of the Requirements for the Award of the Degree ofBachelor of Technologyin Electronics and Communication EngineeringSubmitted ByCHARLA RAJDEEP REDDY15881A0409MAMIDI ADHARSH BHARAT15881A0430ROTTELA RAMESH16885A0409Under the esteemed guidance of Mr. K.H.Murali Assistant professor2352675257175Department of ECEAccredited by NBADepartment of Electronics and Communication EngineeringVardhaman College of Engineering(AUTONOMOUS)(Approved by AICTE, Affiliated to JNTUH&)2015 - 2019ACKNOWLEDGEMENTThe satisfaction that accompanies the successful completion of the task would be put incomplete without the mention of the people who made it possible, whose constant guidance and encouragement crown all the efforts with success. I wish to express my deep sense of gratitude to Mr.K.H.Murali,Assistant Professor& Project Supervisor, Department of Electronics & Communication Engineering, Vardhaman College of Engineering, for her able guidance and useful suggestions, which helped me in completing the project work, in time. I would like to thank Prof. N. Umamaheswara Rao, Project Coordinator, Department of Electronics & Communication Engineering, Vardhaman College of Engineering, for his expert guidance and encouragement at various levels of my Project. I am particularly thankful to Prof. Y. Pandurangaiah, Head of Department of Electronics and Communication Engineering for his guidance, intense support and encouragement, which helped us to mould my project into a successful one.I show gratitude to my honorable Principal Dr. S. Sai Satyanarayana Reddy, for having provided all the facilities and support. I avail this opportunity to express my deep sense of gratitude and heartful thanks to Dr Teegala Vijender Reddy, Chairman and Sri Teegala Upender Reddy, Secretary of VCE, for providing congenial atmosphere to complete this project successfully. I also thank all the staff members of Electronics and Communication Engineering department for their valuable support and generous advice. Finally thanks to all my friends and family members for their continuous support and enthusiastic help. CHAPPIDI RANJITH REDDY(14881A04K1) INDHARAPU SAI SAMPREETH(14881A04L3) SAINI MADHUKAR (15885A0441) ABSTRACTAbstract— In this communication, a novel broadband dual circularly polarized (CP) antenna is presented. This antenna consists of an U-shaped slot to achieve broadband CP radiation and two 50- microstrip-fed ports to realize both right-hand circular polarization and left-hand circular polarization at the same frequency band. The axial ratio bandwidth (ARBW) is greatly broadened by moving the feeding ports to upper portion of the U-shaped slot. To verify this design, the proposed antenna is fabricated and measured. The measured ?10 dB reflection coefficient bandwidth is about 114.4% (1.80–6.61 GHz) and the 3-dB ARBW is approximately 110.5% (1.83–6.35 GHz). The isolation between two ports is better than 14.8 dB within the ARBW.For the application of RFID communication we are using miniatured antennas. In this project for better communication an antenna proposed with the dimensions of 48mm x48mm x1mm. The proposed antenna uses microstrip probe feeding. Simulation and implementation can be done by using ANSYS High Frequency Structured simulator(Finite Element Method).It is proposed to design a U-shaped slot antenna with broadband dual circularly polarized radiation and simulate it using ANSYS HFSS.TABLE OF CONTENTSAcknowledgementsAbstract 1. INTRODUCTION AND SCOPE OF PROJECT1.1. INTRODUCTION1.2. OBJECTIVE OF THE PROJECT 1.3. MOTIVATION OF THE PROJECT 2.FUNDAMENTALS OF MICROSTRIP PATCH AND COPLANAR WAVEGUIDE FEEDING 2.1. ANTENNA 2.1.1. ROLE OF ANTENNA 2.1.2. TYPES OF ANTENNA 2.2. ANTENNA PARAMETERS 2.3.1 MICROSTRIP PATCH ANTENNA 2.3.2 SLOT ANTENNA 2.4. POLARIZATION 2.4.1. TYPES OF POLARIZATION 2.4.2 APPLICATIONS OF ANTENNA POLARIZATION 3. DESIGN METHODOLOGY 3.1. INTRODUCTION TO HFSS 3.1.1. APPLICATION OF HFSS 3.1.2 . HFSS FEATURES 3.2DESIGN OF PROPOSED ANTENNA 3.2.1 THEORTICAL ANALYSIS 3.3 SIMULATION OF THE PROPOSED ANTENNALaunching ANSYS HFSSSetting Tool OptionsOpening a New ProjectSet Solution Type 7524750517525Set Model UnitsSet Default MaterialValidation check 3.4 SIMULATION RESULTS AND DISCUSSIONSA.VSWR B.3D POLAR PLOTC.RADIATION PATTERN WITH AZIMUTHAL ANGLE D.AXIAL RATIO 4.CONCLUSIONSReferences CHAPTER – 1 INTRODUCTION AND SCOPE OF PROJECTINTRODUCTION:Overview of Communication:Communication is basically the transfer of information from one system to another through some channel which may be wired or wireless. Nowadays for long distance communication, electromagnetic spectrum is used. The electromagnetic spectrum is a natural resource and this resource is fully utilised by antenna systems. In the communication industry, wireless communication is growing very rapidly. From the last few years cellular systems have grown exponentially and there are billions of users all over the world. The cellular systems have become a major business tool in the world and an important part of our daily life in almost all the leading countries. Cellular systems employ wireless communication. Wireless communication is that in which there is no direct connection between two or more points and still there is transfer of information between them. The name “Wireless” is basically used for referring a radio transmitter and receiver. OBJECTIVE OF THE PROJECT:The main objective of the project is to design a U-shaped slot antenna which operates at 1.8 to 6.5GHz frequency using HFSS simulation software. To get better RFID communication by operating antenna at a frequency of 3.6GHz.The proposed antenna is more useful to RFID applications.MOTIVATION OF THE PROJECT:Radio frequency identification (RFID) technology is a wireless communication technology that is used to uniquely identify tagged objects or people. RFID is an emerging technology and one of the most rapidly growing segments of today’s automatic identification and data capture (AIDC) industry. For that we are going to use very small antennas. For this reason an antenna proposed with very small dimensions which uses Broadband dual circularly polarized technique.CHAPTER – 2FUNDAMENTALS OF MICROSTRIP PATCH AND COPLANAR WAVEGUIDE FEEDING2.1 ANTENNA:An antenna is a type of transducer which converts electrical energy into radio waves (electromagnetic energy) and vice versa. An antenna used with a radio transmitter or radio receiver. During transmission, transmitter supplies a current which is oscillating at radio frequency towards the terminals of antenna and the radiation of energy from the current in the form of electromagnetic waves is done by antenna. During reception, the antenna seizes some power of the electromagnetic wave and produces small amount of voltage at its terminals, which is further applied to the receiver for amplification. Fig .2.1Antenna2.1.1 ROLE OF AN ANTENNA:The main use of radio transmitters and radio receivers is to carry signals or data towards the systems which includes Wi-Fi, remote controlled instruments and point to point transmission links. All systems would require an antenna that is non-bulky and occupies less space. One such antenna is Microstrip Patch Antenna.2.1.2 TYPES OF ANTENNA:Classification of antennas can be based on:Frequency and size: Antennas used for HF are different from the ones used for VHF, which in turn are different from antennas for microwave. The wavelength is different at different frequencies, so the antennas must be different in size to radiate signals at the correct wavelength. Directivity: Antennas can be omnidirectional, sectorial or directive. Omnidirectional antennas radiate the same pattern all around the antenna in a complete 360degrees. The most popular types of omnidirectional antennas are the Dipole-Type and the Ground Plane. Sectorial antennas radiate primarily in a specific area. The beam can be as wide as 180 degrees, or as narrow as 60 degrees. Directive antennas are antennas in which the beamwidth is much narrower than in sectorial antennas. They have the highest gain and are therefore used for long distance links. Types of directive antennas are:YagiBiquadHornpatch antennaParabolic Dish Physical construction: Antennas can be constructed in many different ways, ranging from simple wires to parabolic dishes, up to coffee cans.2.2 ANTENNA PARAMETERS:INPUT IMPEDANCE :For an efficient transfer of energy, the impedance of the radio, of the antenna and of the transmission cable connecting them must be the same. Transceivers and their transmission lines are typically designed for 50Ω impedance. If the antenna has impedance different from 50Ω, then there is a mismatch and an impedance matching circuit is required.Fig.2.2 impedances in an antennaThe input impedance of an antenna is given byRETURN LOSS :The return loss is another way of expressing mismatch. It is a logarithmic ratio measured in dB that compares the power reflected by the antenna to the power that is fed into the antenna from the transmission line. The return loss of an antenna is given byWhere VSWR stands for stands for Voltage Standing Wave Ratio.BANDWIDTH :The bandwidth of an antenna refers to the range of frequencies over which the antenna can operate correctly. The antenna's bandwidth is the number of Hz for which the antenna will exhibit an SWR less than 2:1.Different types of antennas have different bandwidth limitations. Antenna 3dB Beam width is the angle between the half-power of an antenna pattern or beam over which the relative power is at or above 50% of the peak power. Antenna beam width is also known as the half-power.Formula:Beamwidth = 70λ / Dwhere,λ = Wavelength D = Diameter λ = 0.3 / frequencyFig 2.3 BANDWIDTH OF ANTENNADIRECTIVITY AND GAIN :Directivity is the ability of an antenna to focus energy in a particular direction when transmitting, or to receive energy better from a particular direction when receiving.Fig 2.4 DIRECTIVITY OF VARIOUS ANTENNASThe gain of an antenna in a given direction is the amount of energy radiated in that direction compared to the energy an isotropic antenna would radiate in the same direction when driven with the same input power.An antenna normalized radiation pattern as a function of spherical coordinates is given as:The directivity of an antenna is given as:Fig 2.5 GAIN OF ANTENNARADIATION PATTERN :The radiation or antenna pattern describes the relative strength of the radiated field in various directions from the antenna, at a constant distance. The radiation pattern is three-dimensional, but usually the measured radiation patterns are a two dimensional slice of the three-dimensional pattern, in the horizontal or vertical planes. Fig 2.6 RADIATION PATTERNRadiation pattern measurements are presented in either a rectangular or a polar format. Polar coordinate systems may be divided generally in two classes: LINEARLOGARITHMICLINEAR COORDINATE SYSTEM: In the linear coordinate system, the concentric circles areequally spaced, referenced to 0 dB at the outer edge of the plot. Fig 2.7 LINEAR COORDINATE SYSTEMLOGARITHMIC POLAR COORDINATE SYSTEM :In the logarithmic polar coordinate system the concentric grid lines are spaced periodically according to the logarithm of the voltage in the signal. Generally the 0 dB reference for the outer edge of the chart is used.Fig 2.8 POLAR COORDINATE SYSTEMThere are two kinds of radiation pattern: absolute and relative. Absolute radiation patterns are presented in absolute units of field strength or power. Relative radiation patterns are referenced in relative units of field strength or power. BEAMWIDTH An antenna's beamwidth is usually understood to mean the half-power beamwidth. The peak radiation intensity is found and then the points on either side of the peak which represent half the power of the peak intensity are located. The angular distance between the half power points is defined as the beamwidth. Half the power expressed in decibels is 3dB, so the half power beamwidth is sometimes referred to as the 3dB beamwidth. Fig 2.9 BEAMWIDTH OF ANTENNASIDELOBES :No antenna is able to radiate all the energy in one preferred direction. Some is inevitably radiated in other directions. The peaks are referred to as side lobes, commonly specified in dB down from the main lobe.POLARIZATIONPolarization is defined as the orientation of the electric field of an electromagnetic wave. Polarization is in general described by an ellipse. Two special cases of elliptical polarization are linear polarization and circular polarization.In order to transfer maximum power between a transmit and a receive antenna, both antennas must have the same spatial orientation, the same polarization sense and the same axial ratio.Fig 2.10 TYPES OF POLARIZATIONFRONT-TO-BACK RATIO :The front-to-back ratio that is the ratio of the maximum directivity of an antenna in forward direction to its directivity in the rearward direction. The front-to-back ratio is the difference in dB between the level of the maximum radiation, and the level of radiation in a direction 180 degrees.Fig 2.11 FRONT TO BACK RATIO2.3MICROSTRIP PATCH ANTENNA:Nowadays, in mobile communication systems, the requirement of small sized antenna for miniaturisation purpose of mobile units has been increased. Hence, reduced size and enhanced bandwidth are the major considerations in microstrip antennas for practical applications. Therefore, study regarding small size and enhanced bandwidth of micro strip antenna has been greatly increased. In the past few years, great progress in the design of small sized micro strip antenna with dual and circular polarization, dual frequency, broadband and gain enhanced performance has been reported .Fig 2.12 PATCH ANTENNAHowell and Munson developed the first antenna which was practical antenna. Munson showed that the microstrip antenna was a practical antenna to be used in various antenna system problems by using it in missiles and rockets as a flush mounted low profile antenna. Microstrip antenna consists of a conducting patch on upper side of dielectric substrate and a ground plane on the lower side of dielectric substrate. The material of patch is copper or gold and the patch can have any shape such as rectangular and circular etc. On the dielectric substrate the feed line and the patch are photo etched.Wireless technology provides less expensive alternative and a flexible way for communication. Antenna is one of the important elements of the wireless communications systems. According to the IEEE Standard Definitions, the antenna or aerial is defined as “a means of radiating or receiving radio waves". In other words, antennas act as an interface for electromagnetic energy, propagating between free space and guided medium. Microstrip patch antennas are widely used in the microwave frequency region because of their simplicity and compatibility with printed-circuit technology, making them easy to manufacture either as stand-alone elements or as elements of arrays. The advantages of microstrip antennas make them suitable for various applications like, vehicle based satellite link antennas, global positioning systems (GPS), radar for missiles and telemetry and mobile handheld radios or communication devices. In its simplest form a microstrip patch antenna consists of a patch of metal, generally rectangular or circular (though other shapes are sometimes used) on top of a grounded substrate.The commonly available shapes of patch antenna are rectangular, circular, dipole, triangular, square and elliptical with rectangular and circular shapes the most common 2.3.1 SLOT ANTENNA:Slot antennas are antennas that are used in the frequency range from about 300 MHz to 25 Hz. The slot can be circular, rectangular or of any other shape and size, Array of slots are used to have higher gain and higher directivity. A thin slot in an infinite ground plane is the complement to a dipole in free space. It can be fabricated and concealed within metallic objects. The slot will have the same radiation pattern as a dipole with the same dimensions as the slot, except that the E- and H-fields are swapped. The slot is a magnetic dipole rather than an electric dipole, As a result, the polarization is rotated 90?, so that radiation from a vertical slot is polarized horizontally.Construction & Working of Slot Antennas:When an infinite conducting sheet is made a rectangular cut and the fields are excited in the aperture (which is called as a slot), it is termed as Slot antenna. The working of Slot Antenna can be easily understood through Babinet’s principle of optics. This concept gives an introduction to the slot antennas.Babinet’s Principle for optics:Jacques Babinet (1794 - 1872) was a French physicist and mathematician, formulated the theorem that similar diffraction patterns are produced by two complementary screens (Babinet's principle).This principle relates the radiated fields and impedance of an aperture or slot antenna to that of the field of a dipole antenna. The polarization of a slot antenna is linear. The fields of the slot antenna are almost the same as the dipole antenna, but the field’s components are interchanged. A vertical slot has got an horizontal electric field; and the vertical dipole has got a vertical electrical field Babinet’s principle states that- “When the field behind a screen with an opening is added to the field of a complementary structure, the sum is equal to the field when there is no screen”.The above images clearly explain the principle. In all the regions, which are non-collinear with the beam, the above two screens, in figures 1 & 2, produce the same diffraction pattern.Case 1 ? Consider a light source and a conducting plane (field) with an aperture before a screen. The light does not pass through the opaque area, but passes through the aperture.Case 2 ? Consider the light source and a conducting plane of the size of the aperture in the previous case, being held against the screen. The light does not pass through the plane but through the remaining portion.Case 3 ? Combine these two conducting planes of both the cases and put before the light source. The screen is not placed to observe the resultant combination. The effect of screen gets nullified.Babinet’s Principle for Antennas:The dual of a slot antenna would be if the conductive material and air were interchanged - that is, the slot antenna became a metal slab in space.Note that a voltage source is applied across the short end of the slot antenna. This induces an E-field distribution within the slot, and currents that travel around the slot perimeter, both contributed to radiation. The dual antenna is similar to a dipole antenna. The voltage source is applied at the center of the dipole, so that the voltage source is rotated.Zd · Zs = η2 /4Where Zs = impedance of the slot antenna Zd= impedance of its dual antenna. η = intrinsic impedance of free spaceη= 120*π Ohm Zd= Rd + j*XdRd = Real Part and Xd = Reactive Part.Radiation Pattern:The radiation pattern of the Slot antenna is Omni directional, just like ahalf-wave dipole antenna. Take a look at the following illustration. It shows the radiation pattern of Slot antenna drawn in Horizontal and Vertical planes respectively. 2.4 POLARIZATIONFor the electromagnetic wave the polarization is effectively the plane in which the electric wave vibrates. This is important when looking at antennas because they are sensitive to polarization, and generally only receive or transmit a signal with a particular polarization.For most antennas it is very easy to determine the polarization. It is simply in the same plane as the elements of the antenna. So a vertical antenna (i.e. one with vertical elements) will receive vertically polarized signals best and similarly a horizontal antenna will receive horizontally polarized signals.It is important to match the polarization of the RF antenna to that of the incoming signal. In this way the maximum signal is obtained. If the RF antenna polarization does not match that of the signal there is a corresponding decrease in the level of the signal. It is reduced by a factor of cosine of the angle between the polarization of the RF antenna and the signal. 2.4.1 POLARIZATION CATEGORIESThere are several categories of polarization, and within each type there are several sub categories.Linear polarisation:?? Linear polarisation is the most common form of antenna polarisation:Horizontal polarisation:?? This form of antenna polarisation has horizontal elements. It picks up and radiates horizontally polarized signals, i.e. electromagnetic waves with the electric field in the horizontal plane.Vertical polarisation:?? This form of antenna is typified by the vertical elements within the antenna. It could be a single vertical element. One of the reasons for using vertical polarisation is that antennas comprising of a single vertical element can radiate equally around it in the horizontal plane. Typically vertically polarised antennas have what is termed a low angle of radiation enabling a large proportion of their power to be radiated at an angle close to the earth’s surface. Vertically polarised antennas are also very convenient for use with automobiles.Slant polarisation:?? This is a form of antenna polarisation that is at an angle to the horizontal or vertical planes. In this way both vertical and horizontally polarised antennas are able to receive the signal.Circular polarisation:?? This has a number of benefits for areas such as satellite applications where it helps overcome the effects of propagation anomalies, ground reflections and the effects of the spin that occur on many satellites. Circular polarisation is a little more difficult to visualize than linear polarisation. However it can be imagined by visualizing a signal propagating from an RF antenna that is rotating. The tip of the electric field vector will then be seen to trace out a helix or corkscrew as it travels away from the antenna.?Right hand circular polarisation:?? In this form of polarisation the vector rotates in a right handed fashion.Left hand circular polarisation :?? In this form of polarisation the vector rotates in a left handed fashion, i.e. opposite to right handed.2.4.2 Applications of antenna polarization:Different types of polarisation are used in different applications to enable their advantages to be used. Accordingly different forms of polarisation are used for different applications:General radio communications:?? Linear polarization is by far the most widely used for most radio communications applications as the antennas are generally simpler and more straightforward.Mobile communications:?? Vertical polarisation is often used for mobile radio communications. This is because many vertically polarized antenna designs have an omni-directional radiation pattern and it means that the antennas do not have to be re-orientated as positions as always happens for mobile radio communications as the vehicle moves.Long distance HF ionospheric communications:?? Both vertical and horizontal polarisation are used:Horizontal polarisation:?? Wire antennas are widely used for HF communications. These tend to be more easily erected using two poles leaving he wire antenna to be suspended between the two. In this way the antenna is horizontally polarised.For large multi-element antenna arrays, mechanical constraints mean that they can be mounted in a horizontal plane more easily than in the vertical plane. This is because the RF antenna elements are at right angles to the vertical tower of pole on which they are mounted and therefore by using an antenna with horizontal elements there is less physical and electrical interference between the two.Vertical polarisation:?? Antennas consisting of a single vertical element are widely used. The vertically polarised antenna provides a low angle of radiation which enables it to provide good long distance transmission and reception.Medium wave broadcasting:?? medium wave broadcast stations generally use vertical polarisation because ground wave propagation over the earth is considerably better using vertical polarization, whereas horizontal polarization shows a marginal improvement for long distance communications using the ionosphere.Satellite communications:?? Circular polarisation is sometimes used for satellite radio communications as there are some advantages in terms of propagation and in overcoming the fading caused if the satellite is changing its orientation. CHAPTER – 3DESIGN METHODOLOGY3.1 INTRODUCTION TO HFSS :The name HFSS stands for High Frequency Structural Simulator. HFSS is a high-performance full-wave electromagnetic (EM) field simulator for arbitrary 3D volumetric passive device modeling that takes advantage of the familiar Microsoft Windows graphical user interface. It integrates simulation, visualization, solid modeling, and automation in an easy-to-learn environment where solutions to 3D EM problems are quickly and accurately obtained. ANSYS HFSS employs the Finite Element Method(FEM), adaptive meshing, and brilliant graphics to give unparalleled performance and insight to all of 3D EM problems.HFSS is an interactive simulation system whose basic mesh element is a tetrahedron. This allows to solve any arbitrary 3D geometry, especially those with complex curves and shapes, in a fraction of the time it would take using other techniques. Ansoft pioneered the use of the Finite Element Method (FEM) for EM simulation by developing/implementing technologies such as tangential vector finite elements, adaptive meshing, and Adaptive Lanczos-Pade Sweep.The ANSYS HFSS Desktop provides an intuitive, easy-to-use interface for developing passive RF device models. Creating designs, involves the following: 1. Parametric Model Generation – creating the geometry, Parametric Model Generation boundaries and excitations 2. Analysis Setup – defining solution setup and frequency sweep Analysis Setup 3. Results – creating 2D reports and field plots Results 4. Solve Loop - the solution process is fully automated Solve Loop. 3.1.1APPLICATION OF HFSS: Today, HFSS continues to lead the industry with innovations such as Modes-to-Nodes and Full-Wave Spice. ANSYS HFSS has evolved over a period of years with input from many users and industries. In industry, ANSYS HFSS is the tool of choice for high-productivity research, development, and virtual prototyping. HFSS finds applications in wide range of areas. ANSYS HFSS can be used to calculate parameters such as S-Parameters, Resonant Frequency, and Fields.Some of applications of HFSS are :Package Modeling–BGA, QFP, Flip-ChipPCB Board Modeling–Power/Ground planes, Mesh Grid Grounds, Backplanes Silicon/GaAs-Spiral Inductors, TransformersEMC/EMI –Shield Enclosures, Coupling, Near-or Far-Field RadiationAntennas/Mobile Communications–Patches, Dipoles, Horns, Conformal Cell Phone Antennas, Quadrafilar Helix, Specific Absorption Rate(SAR), Infinite Arrays, Radar Cross Section(RCS),Frequency Selective Surfaces(FSS)Connectors–Coax, SFP/XFP, Backplane, Transitions Waveguide–Filters, Resonators, Transitions, Couplers Filters–Cavity Filters, Microstrip, Dielectric.Microwave transitionsWaveguide componentsThree-dimensional discontinuitiesPassive circuit elements3.1.2 HFSS FEATURES:HFSS has many significant features which attracts the user. Some of the features of HFSS are:Computes s-parameters and full-wave fields for arbitrarily-shaped 3D passive structures.Powerful drawing capabilities to simplify design entry.Field solving engine with accuracy-driven adaptive solutions.Powerful post-processor for unprecedented insight into electrical performance.Advanced materials.Model Library-including spiral inductors.Model half, quarter, or octet symmetry.Calculate far-field patterns.Wideband fast frequency sweep.Create parameterized cross section models- 2D models.3.2 DESIGN OF PROPOSED ANTENNA3.2.1 THEORTICAL ANALYSISFig 3.1Geometrical layout of the U-shaped slot antennaThe geometrical layout of the proposed CPW-fed rectangular patch antenna is shown in Fig.3.1. The top view and side view of proposed dual-CP antenna are shown in Fig. 1. This antenna is printed on a square FR4 substrate material (εr = 4.4, tanδ = 0.02). It consists of two microstrip-fed ports (Port 1, Port 2), an U-shaped slot, and a frame structure ground. This CP antenna uses a microstrip-fed rectangular radiator to excite an U-shaped slot. CP wave is generated by two orthogonal E vectors with equal amplitude and 90° phase difference. The broadband CP wave of this antenna is mainly implemented by the U-shaped slot (mode1) and asymmetric feeding structure (mode2). The U-shaped slot can provide mode1 with superimposed perturbation orthogonal current distributions on the outer contour surface at lower frequency. And the asymmetric feeding structure provides another mode2 withcurrent distributions in x and y directions on the inner contour surface at upper frequency. A broadband CP antenna is achieved by superimposing the two modes.When Port 1 is excited and Port 2 is matched, it radiates right hand circular polarization (RHCP) wave. On the contrary, it radiates left-hand circular polarization (LHCP) wave. Since the symmetry structure, this work just gives the simulated and measured results (Simulated by HFSS 13.0) when Port 1 is excited and Port 2 is matched. As shown in Fig. 1, the length of the radiator (LM = L + G) is approximately quarter wavelength of the slot at the mid-frequency (FM) of the ARBW. The LM is roughly evaluated where εr is the relative permittivity of the loaded substrate FR4. Size unit is in millimeters. The effect of other geometric parameters on the frequency range is not patency. This antenna is designed to work at the center frequency of 4 GHz, the estimated LM is about 10.5 mm,which is very close to the simulation value (L + G = 8.5 + 1.5 = 10 mm). The length of the wide U-shaped slot (Length?slot) is about halfspace wavelength (λ0/2) at lowest frequency (2 GHz) (Length?slot ≈ λ0/2 = 300/2/2 = 75 mm). The estimated wide Length?slot is about 75 mm (λ0/2 = 300/2/2 mm), which is also very close to the simulation value. To cut an U-shaped slot with λ0/2, a square FR4 substrate material with dimension of 48 × 48 mm2 is used. 3.3SIMULATION OF THE PROPOSED ANTENNALaunching Ansoft HFSS– To access Ansoft HFSS, click the MicrosoftStartbutton, select Programs, and select the Ansoft, HFSS 17.0 program group. Click HFSS 17.0.Setting Tool Options– Select the menu item Tools > Options > HFSS OptionsClick the General tab– Use Wizards for data input when creating new boundaries: Checked– Duplicate boundaries /mesh operations with geometry: CheckedClick the OK button– Select the menu item Tools > Options > Modeler Options.Click the Operation tab– Automatically cover closed polylines: Checked– Select last command on object select: CheckedClick the Drawing tab– Edit property of new primitives: CheckedClick the OK buttonOpening a New Project – In HFSS Desktop, click on the Standard toolbar, or select the Menu item File > New.73723501022350– From the Project menu, select Insert HFSS Design.Fig 3.2 Opening a new project Set Solution Type 75247505175257219950-20955– Select the menu item HFSS > Solution Type 782955035496579819501790707677150-125730Choose Driven TerminalClick the OK buttonSet Model Units– Select the menu item Modeler > Units Select Units: mmClick the OK buttonSet Default Material– Using the 3D Modeler Materials toolbar, choose SelectClick the Add Material button– For the Material Name type: My_Sub– For the Value of Relative Permittivity type:2.33– For the Value of Dielectric Loss Tangent type: 4.29e-4– Click the OK buttonClick the OK buttonValidation checkFig.3.3 Validation check3.4 SIMULATION RESULTS AND DISCUSSIONSTo investigate the performance of the proposed antenna configurations in terms of achieving the required results a commercially available moment method based CAD tool-IE3D, was used for required numerical analysis and obtaining the proper geometrical parameters in Fig 3.1.A. VSWR:B. 3D POLAR PLOT: C. Radiation Pattern with Elevation and Azimuth Angles:The far-field radiation patterns at the operating frequency for the constructed prototype of the proposed antenna are also examined.Fig 3.5 2D Azimuthal Pattern at 3.6GHzD. AXIAL RATIO:CHAPTER -4CONCLUSIONA novel broadband dual-CP U-shaped slot antenna is proposed in this communication. The U-shaped slot is excited by two asymmetric microstrip-fed ports. By adjusting the position of fed ports and the proportion of U-shaped slot, a broadband dual-CP antenna with good isolation is achieved. The 10-dB return-loss bandwidth is 114.4% (1.80–6.61 GHz), 3-dB ARBW is 110.5% (1.83–6.35 GHz), and the isolation between two ports is better than 14.8 dB. The antenna gain is stable and varies from 3.1 to 4.5 dBic. Therefore, this antenna is very suitable for broadband dual-CP communication system. REFERENCES:[1] M. S. Ellis, Z. Zhao, J. Wu, X. Ding, Z. Nie, and Q.-H. Liu, “A novel simple and compact microstrip-fed circularly polarized wide slot antenna with wide axial ratio bandwidth for C-band applications,” IEEE Trans. Antennas Propag., vol. 64, no. 4, pp. 1552–1555, Apr. 2016.[2] Y. Li, Z. Chen, X. Qing, Z. Zhnag, J. Xu, and Z. Feng, “Axial ratio bandwidth enhancement of 60-GHz substrate integrated waveguide fed circularly polarized LTCC antenna array,” IEEE Trans. Antennas Propag., vol. 60, no. 10, pp. 4619–4636, Oct. 2012. [3] T. Kumar and A. R. Harish, “Broadband circularly polarized printed slot-monopole antenna,” IEEE Antennas Wireless Propag. Lett. vol. 12, 2013. ................
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