Fed Corner Truncated Microstrip Patch Antenna

Fed Corner Truncated Microstrip Patch AntennaUltra-Wide band communications attracted great interest of researchers as it has become unity of the most promising technologies for short plod mobile systems, Personal Area Networks (PAN) and eminent speed indoor data communication applications. FCC mentioned parameters for the stand in functioning of UWB approachs and they rent to cover the bandwidth specified by FCC to attain adequate performance.UWB has the advantage of high data rates with extremely small interference to separate narrow band systems. The ultra short pulses provide extremely good spatial root, as the range provided by UWB is enough to seize down the major applications of daily life like in ground penetrating radars, parking radars, biomedical imaging, precision tracking and location finding. Various types of UWB overtures have been proposed and implemented with contrasting escapeing techniques, such as transmission system line, probe feed, dual feed and two-dimensional loopguides (CPW).A compact approach design fed by coplanar waveguide (CPW) is proposed. Over all dimensions of transmitting aerial ar 28-24 mm2. The design is manufacture and further analyzed to confirm its proper working in UWB range. The design of transmitting aerial is quite flexible as fiddling with the stain of microstrip antenna has been do in order to enhance the bandwidth which is the most valued obsession in the accredited milieu. On the other hand, CPW has m whatsoever advantages such as low actinotherapy leakage, less dispersion at higher frequence, small mutual duo amidst two adjacent lines which is helpful to show circuit elements close together without adding an additional layer of substrate and coplanar capability. Using CPW as feeding grammatical construction to excite a patch antenna has become very popular recently.The proposed antenna byers an excellent performance for UWB systems by providing bandwidth ranging up to 15.65GHz. Crit ical design parameters feed loss and shaft convenings ar investigated in detail. Proposed antenna provides good immunity matching, motionless gain characteristics and consistent radiation exercises over its almost whole frequency band of interest.Chapter 1IntroductionProject OverviewIEEE defines antenna as a device for radiate and receiving electromagnetic waves. They are used both as transmitter and receiver. This is era of wireless communication. Antennas are an important means of wireless communications now days. The need of snip is compact small size antennas with enhanced bandwidth and gain. Amongst all antenna types microstrip patch antennas are most common. They are light in tilt and consume low indi canfult. But patch antennas have disadvantage that they have narrow bandwidth. Many techniques are used to enhance bandwidth.Ultra extensive band antennas have many applications and for many years they have been used for wideband and spread spectrum features in rada r systems. The UWB performances of antennas result from excitation by non-sinusoidal signals with quickly time-varying performances 1. UWB are low power consumption antennas and are for un cleard applications. As name suggests, they have broad spectrum.Problem StatementUltra wideband technology is used in low power, short range and high bandwidth communication. In UWB through spreading culture can be transmitted over a bigger bandwidth and spectrum is also shared with the other users at the same time.Federal Communication Commission (FCC) allocated the license free band of 3.1GHz-10.6GHz for use in UWB applications. Since then there is a growing demand of UWB antennas for high data rate applications i.e. wireless personal knowledge base engagement (WPAN).UWB has had a important effect on antenna design. The major challenge in UWB antenna design is to achieve wide impedance bandwidth and stable gain while maintaining high radiation efficiency.Project ObjectiveThe purpose of this p roject is to design, stimulate, analyze and fabricate ultra wide band antenna employ co- monotonicr waveguide.Design and analysis of a compact antenna fed by CPW for UWB Applications is proposedBandwidth of the proposed antenna is 15.65 GHz.Antenna offers an excellent performance for ultra-wide band systems by providing an ultra-wide bandwidth ranging from 3.1 18.75 GHz.Gain of the proposed antenna is 4.91dBi over its almost whole frequency band of interestSmall size of antenna makes it suitable for applications which demand miniaturization of antenna structure and scuttlebutt impedance of 50 .MethodologyWe have simulated the designed antenna using Ansoft HFSS. Then the simulated antenna is fabricated and tested on the network analyzer. The simulated and measured results are also explained.Organization of the thesisThis report is divided into 6 chapters.Chapter 2 presents the fundamental parameters of antenna. This includes an explanation of various parameters related to antenna performance including radiation intensity ,radiation pattern, power density , gain, directivity and icyization etc.Chapter 3 discusses the Microstrip Patch Antenna and Feeding techniques.Chapter 4 includes Ultra wide band microstrip patch antenna, history of UWB antennas, their features and advantages.Chapter 5 describes antenna design, simulated results, 2D and 3D radiation patterns for different frequencies and fabricated results.Chapter 6 concludes the entire work done throughout the designing of proposed antenna. Conclusion and future work helps to explore enormity of the subject.Chapter 2Fundamental Parameters of Antenna2.1 shaft PatternThe radiation pattern describes the military capability of the radiated subject area in different directions from the antenna, at a constant distance. The radiation pattern is also reception pattern, as it describes the receiving properties of the antenna. It is defined as a mathematical function or a graphical representation of the radi ation properties of antenna as a function of space coordinates. In most cases the radiation pattern is determined in far domain of a function regions and is defined as a function of the directional coordinates. Radiation properties include power flux density, radiation intensity, theatre of operations strength, directivity phase or polarisation 2.The radiation pattern is three-dimensional, but measured patterns are usually two dimensional in vertical or horizontal piece of paper view. These measured patterns are presented in either rectangular or polar format. Following figure shows radiation pattern of an antenna in polar two-dimensional and Cartesian coordinate systems.http//www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/images/0900aecd806a1a3e_null_null_null_08_07_07-03.jpg fancy-2.1 Radiation Pattern of an antenna in Cartesian and polar coordinatesRadiation patterns are further categorized as relative and direct radiation patterns. Absolute radiation patterns ha ve absolute units of power or field strength. Relative radiation patterns are presented in relative units of power or field strength. The radiation measurement patterns are mostly relative to isotropic antennas, absolute gain of the antenna is established by antenna gain transfer rule.The radiation pattern varies with the distance i.e. the patterns in near filed and far filed are different. The field pattern that exists close to the antenna is known as near filed, and far-field refers to the field pattern that exists at large distances. The far-field is called radiation field. Radiation field and power are what is commonly of interest, so antenna patterns are generally measured in the far-field region. For antenna pattern measurement the distance should be chose large enough non to be in near-field or in far field. The minimal allowed distance depends on the dimensions of the antenna relative to the wavelength. The figure for this distance isrmin = 2d2/ (2.1)Where, rmin is the m inimum distance from the antennad is the largest dimension of the antenna is the wavelength.2.1.1 Radiation Pattern LobesRadiation lobes are defines as portion of radiation pattern bounded by regions of relatively rachitic radiation intensity 3. These lobes are categorized as followMajor LobesMinor LobesSide LobesBack Lobes2.1.2 Major LobeA major lobe is defined as the radiation lobe containing the direction of maximum radiation 2. Normally an antenna has one major lobe.2.1.3 Minor LobeAny lobe except major lobe is called minor lobe. It usually represents the radiation pattern which is not desirable.2.1.4 Side LobeA human face lobe is a radiation lobe in any direction other than the main lobe 2. Usually a side lobe is next to the main lobe and is in direction to the main lobe.2.1.5 Back LobeA back lobe is a radiation lobe whose axis makes an angle of approximately 180 with watch to the beam of an antenna or that is directed away from the main lobe 2.FileTypical Antenna Pattern.jp gFigure 2.2 An illustration of major and minor lobes of radiation pattern2.2 Field neck of the woodssThe antenna field are divided into three regionsReactive near fieldRadiating near field (Fresnel)Far field (Fraunhofer)http//www.nearfield.com/images/ system-ffdist.jpgFigure 2.3 Figure of Near Field and Far Field Regions2.2.1 Reactive Near FiledIt is the region immediately around the antenna. In this region the reactive filed predominates. The distance of this filed with antenna is usually R2.2.2 Radiating Near Field (Fresnel)Radiating near filed is defines as that region of the field of an antenna amid the reactive near-filed and the far-filed region wherein radiation fields predominate and wherein the angular field distribution is dependent upon the distance from the antenna 2. The distance of inner boundary is R2.2.3 Far Field Region (Fraunhofer)Far Field region is defined as that region of the field of an antenna where the angular filed distribution is essentially independent of the distance from the antenna 2.2.3 Radiation IntensityRadiation Intensity is the power radiated from an antenna per unit solid angle. It is the parameter of far field radiation.2.4 DirectivityDirectivity is figure of merit for antennas. It is the power density an antenna radiates in direction of maximum radiation to the average power density radiated by an isotropic antenna. Directivity for an isotropic antenna is perpetually unity. It is expressed asD= (2.2a)(2.2b)Where, D is directivity and U is radiation intensity, Uo is Intensity if an isotropic source and Prad is complete radiation power.2.5 GainThe gain and directivity of an antenna are closely related to each other. However for gain in denominator it is total power accepted by an antenna rather than total power radiated by an antenna.G= (2.3)Gain is dimensionless. According to IEEE standards, gain doesnt include losses arising from impedance mismatching or polarization mismatches.2.6 BandwidthThe bandwidth is basically the difference or range between highest and lowest frequencies on which an antenna is operated. It is advantageous to have an antenna with high bandwidth. The bandwidth is expressed in term of ratio of upper cut off to the lower cutoff for broadband antennas.2.7 BeamwidthBeamwidth is the angle usually measured in degrees between the -3dB power radiated in the main lobe of radiation pattern.img383Figure 2.4 Illustration of Beamwidth2.8 drop LossIt is the amount of power that is reflected back in to the transmission line due to mismatching or any other error. It is the efficiency of power delivered to the load from the transmission line. Mathematical representation of Return loss isRL = 10log (2.4)Return loss is measured in dB.http//www.mwrf.com/Files/30/11240/Figure_05.gifFigure 2.5 Return Loss2.9 polarizationPolarization is defined as intend of reference of the electric field of the wave radiated by the antenna. It is categorized in three typesLinearCircularElliptical2.9.1 Linea r PolarizationWhen there is zero phase difference between x and y component of a wave then polarization is called linear polarization. Linear polarization is further divided intoHorizontal polarizationVertical polarizationhttp//www.ccrs.nrcan.gc.ca/glossary/images/3104.gifFigure 2.6 Linear Polarization2.9.1.1 Horizontal PolarizationHorizontal polarization is the one in which wave propagates in x-direction and there is no propagation along y direction. A horizontally polarized wave is explained as a function of time T and E-field positionEx = E1 sin ( t z) (2.5)http//www.cfht.hawaii.edu/manset/PolHoriz.gifFigure 2.7 Horizontal Polarization2.9.1.2 Vertical PolarizationVertical polarization is the one in which wave propagates in y-direction and there is no propagation along x direction. It can be written in mathematical form asEy = E2 sin ( t z) (2.6)http//www.cfht.hawaii.edu/manset/PolVert.gifFigure 2.8 Vertical Polarization2.9.2 Circular PolarizationIf there is play off phase diff erence between two waves then there is circular polarization, either clockwise or anticlockwise. Wave moving in clockwise whirling is said to be left circularly polarized and the one propagating in counterclockwise rotation is right circularly polarized. Mathematically it is defined asEx = E1 sin (t z) (2.7)Ey = E2 sin (t z + ) (2.8)E1 is the amplitude of wave linearly polarized in x direction.E2 is the amplitude of wave linearly polarized in y direction. is the phase difference.http//www.cfht.hawaii.edu/manset/PolCirc.gifFigure 2.9 Circular Polarization2.9.3 Elliptical PolarizationIf two waves have inadequate amplitude or phase then there is elliptical polarization.graphic 1Figure 2.10 (a) Graphical Representation of Elliptical Polarizationhttp//www.nsm.buffalo.edu/jochena/images/elliptic2.gifFigure 2.10 (b) three-D view of Elliptical Polarization2.10 Voltage Standing RatioVSWR is the ratio between maximum voltage and the minimum voltage. If there is a difference between load im pedance and input impedance then there occurs reflection which causes instructive interference and destructive interference. Instructive and destructive interference produces maximum and minimum amplitudes respectively. Mathematical Expression for VSWR isVSWR= (2.9)http//www.microwaves101.com/encyclopedia/images/VSWR/waves5.jpgFigure 2.11 Different Voltage amplitudes at different distances2.11 Types of antennasThere are six different types of antennas 2.Microstrip Patch Antenna electron lens AntennaWire AntennaArray AntennaReflector AntennaAperture Antenna2.11.1 Microstrip Patch AntennaMicrostrip patch antennas fall into the category of printed antennas 4. A radiating patch is printed on a grounded substrate which is usually feed via a transmission line or coaxial cable. Patch can be of any shape and size i.e. circular, square, triangular or rectangular. Amongst all printed antennas i.e. Dipole, Slots, Tapered Slots antennas Microstrip Patch Antennas are most famous. They are small in size, light in weight and low power consuming. But their bandwidths are smaller and have low gain. They are gentle to integrate, good radiation control and cost of production is low. To gain bandwidth many techniques are used that is introducing slots and slits etc. They are used commercially in radars, wireless communications, satellites and mobiles etc.Figure 2.12 Microstrip patch Antennahttp//images.books24x7.com/bookimages/id_22121/fig188_01.jpgFigure 2.13 (a) immaterial Patch Antenna (b) Circular Patch AntennaMicrostrip Patch antennas are used in Microwave frequency range. They are used in arrays to addition the bandwidth and gain and for other purposes.http//www.antennamagus.com/database/antennas/99/Stacked_microstrip_patch_array-antenna_design.pngFigure 2.14 Array of rectangular patch antennas2.11.2 Lens AntennaLens antennas are used to convert spherical radiated waves into unwavering waves in specific direction by using a source with microwave lens. It actually stop s the divergent radiated energy to spread in undesired directions. These are mostly used for the high frequencies. A lens antenna may be of concave or convex shape. They are directional antennas and can scan wider angles. In comparison to reflectors their gain is 1 or 2 dB less. Lens antennas may be constructed of non-metallic dielectrics or of metallic (artificial) dielectrics 5.http//www.xibao-electronictech.com/images/product/2/210Lens-Antenna.gifhttp//telecom.esa.int/telecom/media/img/largeimage/WaveguideLensAntennaPrjObj_404.jpgFigure 2.15 (a) Lens Antenna Figure 2.15 (b) Wave guide Lens Antenna2.11.3 Wire AntennaWire antennas consist of a unsophisticated wire that is used to radiate electromagnetic energy. These wire antennas can be of different shapes. Most commonly used are straight wire antennas i.e. dipoles, loops and helix. Beside half-wave dipoles and fasten on and quarter wave monopoles, wires of arbitrary lengths are often used to form antennas. Wire antennas can be vertical, horizontal or sloppy with respect to the ground. They may be fed from centre, at end or anywhere in between. The wires can be thick or thin, the radiation of antenna depends upon the thickness of the wire. Antennas with length larger than /2 are called Long-wire antennas.Figure 2.16 (a) Wire Antennas (a) Figure 2.16 (b) Dipole Circular loop2.11.4 Array AntennaArray antennas are made up of more than one element basic of which is a dipole. Array antennas are the combination of radiating elements in such way that the radiation from these add up large(p) maximum or minimum radiation in a specific direction. They are used for higher directivity. They are made up of helices, dishes and other antennas. These elements are arranged to form broadside, end fire, collinear, driven and patristic arrays 5. They are used in applications in which radiation cannot be achieved from single radiating element. They are low weight and low cost antennas. Examples of array antennas are Yagi-U da,http//www.tennadyne.com/images/tennlpdanavy.JPGFigure 2.17 Log Periodic Dipole Array Antenna2.11.5 Reflector AntennaThey are wide used to modify the radiation pattern of radiating elements. They are classified as active and passive reflectors. The active reflectors have corners made up of scan surfaces and they include periscopic antennas, flat-sheet reflectors and corner-reflector antennas. An active reflector may have corner elliptical, parabolic or spherical shape. Active reflectors include parabolic dish, truncated parabola, pill recess etc. Reflectors are simple in design, involve only one surface and obey simple faithfulnesss of optics. The applications of reflector antennas are radars and other point to point communication systems 5.http//www.sameercal.org/images/reflector_antenna.jpgFigure 2.18 A co-secant Reflector Antenna2.11.6 Aperture AntennaAperture antenna is an important antenna for space communication. As the name suggests they consist of some perdition throug h which electromagnetic waves are transmitted or received. Apertures may be of any shape i.e. rectangular, circular or spherical. Larger the size of antenna larger will be the gain. Aperture antennas have to be placed carefully because they have narrow beam widths. Examples of aperture antennas include waveguides, reflectors horns, slots and lenses. Aperture antennas are commonly used in aircraft and space vehicle applications.http//www.analyzemath.com/antenna_tutorials/introduction_3.gifFigure 2.18 Horn Aperture AntennaChapter 3Microstrip Patch Antenna and Feeding techniques3.1 IntroductionSpaceships, aircrafts and other military applications such as missiles where important constraints to care are performance, manufacturing expenditures, smooth profile and ease of installation and now a days other systems such as wireless communication requires similar type of specifications to consider . And the basic component which is required by these listed applications for transmission of instructions or data and to receive these instructions on the receiver end is antenna. Hence to gratify the requirements listed above e.g. smooth profile, cost and performance etc Microstrip antennas are used.Microstrip antennas are diminutive profile, conformable to planar and non-planar surfaces, easy and cheap to construct using the up to battle printed circuit technology. Microstrip antennas have very flexible behavior to polarization, resonant-frequency, and impedance and radiation pattern. They are also used to increase the bandwidth. They consist of a ground plane over which a substrate is mounted and the radiating patch is mounted on the substrate. Generally the ground plane and the dielectric substrate have equal length and width. The Microstrip antennas are illustrated by the width, length and the height of the dielectric substrate which is sandwiched in between the ground plane and the radiating patch3.2 Structural somaThe structural configuration of micro strip patch antenna is shown in figureFigure 3.1 Structural Configuration of Patch AntennaIt consist of a thin (tFigure 3.2 Side View of Patch AntennaThe length of the patch is usually /3 3.3 Formula for Rectangular Patch AntennaTo draw the width of the patch we use the formula(3.1)And the length of the patch can be drawn as(3.2)To reduce the fringing effects we use the following formulaL= 0.412h (3.3)Here L is the trimmed length from antenna.(3.4)3.4 Feeding MethodsFollowing feeding methods are most popular and are used with microstrip antennas1. Microstrip line feed2. coaxial probe feed3. Aperture pair feed4. Proximity coupled feed5. coplanar waveguide feedThese methods are either contacting or non-contacting. Contacting methods are those in which there is a direct contact between the transmission line and the radiating surface whereas in non-contacting methods, electromagnetic field coupling method is used to transfer the power.3.4.1 Microstrip Line FeedIn this feeding method, the line fee d is conducting strip of small width as compared to the patch. It is the easiest feeding method easy to fabricate and simple to model. The radiating strip is placed at radiating patchs edge and it is of the same material that is used for patch. If length of the strip is greater than the wavelength, losses will be generated. It can be reduced if the strip line has a substrate with high dielectric constant and low weight, so that the fields are confined to the strip line. A line feed of dimensions 17x3mm is used to obtain 50 input resistance.Figure 3.1 Patch with Microstrip Line Feed3.4.2 Coaxial probe feedIn coaxial probe feeds, coax inner conductor is attached to the radiating patch while the other conductor is connected to the ground plane. It is used widely. Its fabrication is easy and has low spurious radiation that is radiation outside the band frequency. It is has narrow bandwidth and it is hard to model for thick substrate. unified also becomes difficult for thicker substrat e because of increase length of probe make it more inductive, its inductance effect can be reduced by using a series of capacitors.Figure 3.2 Patch with coaxial probe feed3.4.3 Aperture coupling feedIt is the non-contacting feed. The two substrates are separated by ground plane in it. The microstrip feed line is on the bottom side of the lower substrate there is a whose energy is coupled to the patch through a slot on the ground plane which separates the two substrates. A material with higher dielectricity is used for bottom substrate therefore, by this arrangement independent optimization of the feed mechanism and the radiating element can be carried out.For top substrate a thick, low dielectric constant material is used. The ground plane between the two substrates isolates the feed from the radiating element and minimizes the interference. The configuration is shown in the figureFigure 3.3 Patch with aperture coupling feedMatching is performed by authoritative the width of the fe ed line and the length of the slot. Amongst all four techniques this is the hardest to fabricate and has narrow bandwidth. It is somehow easy to model and has moderate spurious radiation.3.4.4 Proximity coupling feedIn this feeding method, microstrip line is placed between two substrates and the radiating patch is placed on the upper substrate. This coupling is capacitive in nature. This coupling has the largest bandwidth as high as 13%. It is easy to model and has low spurious radiation. Its fabrication is somehow difficult. However, length of the stub help in improving the bandwidth, and width-to-line ratio of the patch can be used to control the match. The coupling feed is shownFigure 3.4 Patch with Proximity Coupling Feed3.4.5 Coplanar Waveguide FeedThis feeding technique is used when patch antenna is used in microwave monolithic integrated circuits (MMIC). The coplanar feed is fabricated on a ground plane and coupling is achieved through a slot. This feeding method reduces the radiation from feed structure because of its unusual method of coupled slot. Since CPW (coplanar waveguide) has many advantages such as low radiation leakage, less dispersion and small mutual coupling between two adjacent lines, which is helpful to place circuit elements close together without adding an additional layer of substrate, using CPW as the feeding structure to excite the patch antenna through a slot has become very popular recently. In addition, CPW structure can maintain constant characteristic impedance while varying its geometry, which provides a better impedance matching possibilityFigure 3.5 Patch with Coplanar Waveguide Feed3.3 Categorization on the basis of bandwidth-On the basis of range of frequency bands, microstrip patch antennas can be categorized into three main classes which areantenna for narrow band applicationsantenna for wide band applicationsantenna for ultra wideband applicationsChapter 4ULTRA WIDEBAND4.1 IntroductionA series of very short baseband pul ses with time duration in nano-seconds that exist on ALL frequencies simultaneously. blink of an eye repetition frequency (PRF) can range from hundreds of thousands to billions of pulses/second. Very low power 41dbm/MHz (FCC) and wide bandwidth 3.110.6 GHzModulation techniques includepulse-position modulationbinary phase-shift keyingAndothers intercommunicate technology that modulates impulse based waveforms instead of continuous carrier waves4.1.1 Narrow band vs. Wide band signalsUWB could be used to indoor(a), short-range communications for high data rates, OR Outdoor, long-range, but for very low data rates4.1.2 Large Relative BandwidthUWB is a form of extremely wide spread spectrum where RF energy is spread over gigahertz of spectrum. Wider than any narrowband system by orders of magnitude. Power seen by a narrowband system is a fraction of the total.UWB signals can be designed to look like imperceptible random noise to conventional radios4.1.3 Large Fractional BandwidthLarge f ractional bandwidth leads to High processing gain and Multipath resolution and low signal fading. Fractional Bandwidth is the ratio of signal bandwidth (10 dB) to center frequency Bf = B / FC = 2(Fh-Fl) / (Fh+Fl)4.1.4 Scalable Technology with Low PowerUWB benefits from basic information theory results when Signal Bandwidth Data Rate .Power efficient low-order modulation can be used even for relatively high data rates.Data rates can surpass independent of PRF by integrating bit intervals over multiple pulse intervals4.1.5 Multipath PerformanceUltra-wide bandwidth provides robust performance in multipath environments .4.1.6 UWB Data Rates4.2 UWB channelsIndoorWithin a room (LOS NLOS)Investigates the impact ofDistanceRx/Tx antenna heightsAntenna polarizationCmat_dirsuwblimitsindoor5.tifUWB Emission Limit for Indoor SystemsOutdoorCampus environmentLow altitudeMobilityCmat_dirsuwblimitsoutdoor5.tifUWB Emission Limit for Outdoor Hand-held Systems4.3 Emission limits for UWBUWB Emission Limits for GPRs, Wall Imaging, Medical Imaging Systems.Operation is limited to law enforcement, fire and rescue organizations, scientific research institutions, commercial mining companies, and construction companies.UWB Emission Limits for Thru-wall Imaging Surveillance Systems4.4 Features of UWB -Ultra-short pulsesBaseband transmissionLow duty