microstrip antennae design & vhdl ppt

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based on microstrip antenne design and vhdl basics codes and architecture



2. INDEX Antenna Introduction HFSS Software Patch shapes and substrate Design Specifications & Feeding techniques Simulation results VHDL & Its Coding Styles Types of Modelling Hierarchy & statements in VHDL 3. INTRODUCTION An antenna is an electrical device which convertselectric currents into radio waves, and vice versa. Itis usually used with a radio transmitter or radioreceiver. In transmission, a radio transmitter applies anoscillating radio frequency electric current to theantenna's terminals, and the antenna radiates theenergy from the current as electromagnetic waves(radio waves). 4. WHY ANTENNAS ? Need of antenna arisen when two person wanted tocommunicate between them when separated by somedistance and wired communication is not possible. Antennas are required by any radio receiver ortransmitter to couple its electrical connection to theelectromagnetic field. Radio waves are electromagnetic waves which carrysignals through the air (or through space) at thespeed of light with almost no transmission loss. 5. HFSS SOFTWARE HFSS (high frequency structural simulator) is a high-performancefull-wave electromagnetic(EM) fieldsimulator for arbitrary 3D volumetric passive devicemodelling that takes advantage of the familiar MicrosoftWindows graphical user interface. It integrates simulation, visualization, solid modelling,and automation in an easy-to-learn environment wheresolutions to 3D EM problem are quickly and accuratelyobtained. Ansoft HFSS employs the Finite Element Method(FEM),adaptive meshing, and brilliant graphics to giveunparalleled performance and insight to all of your 3D EMproblems. 6. Microstrip AntennaIn its most basic form, a Microstrip patch antenna consists of a radiating patch ononeside of a dielectric substrate which has a ground plane on the other sideFor good antenna performance, a thick dielectric substrate having a low dielectricconstant is desirable since this provides better efficiency, larger bandwidth and betterradiation .Structure of a Microstrip Patch Antenna In genaral Micro strip antennas are alsoknown as PRINTED ANTENNAS . These are mostly used at microwavefrequencies. Because the size of the antenna is directlytied the wavelength at the resonantfrequency. Micro strip patch antenna or patch antennais a narrowband wide-beam antenna. 7. Patch Shapes Are:(a) Single radiating patches(b) Single slot radiator 8. Substrates are:The most commonly used substrates are,1) Honey comb(dielectric constant=1.07)2)Duroid(dielectric constant=2.32)3)Quartz(dielectric constant=3.8)4)Alumina(dielectric constant=10) A thicker substrate will increase the radiationpower , reduce conductor loss and improve Bandwidth. 9. Feeding Techniques: Coaxial feed Microstrip feed Proximity coupled microstrip feed Aperture coupled microstrip feed Coplanar wave guide Line Feed1-Microstrip Line Feed :In this type of feed technique, aconducting strip is connected directly to theedge of themicrostrip patch.This kind of feed arrangement has theadvantage that the feed can be etched onthesame substrate to provide a planarstructure. 10. 2-Coaxial Feed :-The Coaxial feed or probe feed is a very commontechnique used for feeding Microstrippatch antennas.Probe fed Rectangular MicrostripPatch Antenna from topThe main advantage of this type offeeding scheme is that the feed can beplaced at anydesired location inside the patch in order tomatch with its input impedance.This feed method is easy to fabricate andhas low spurious radiation.However, its major disadvantage is that itCoaxial Ground Plane ConnectorSubstratePatch provides narrow bandwidth and isdifficult to model since a hole has to bedrilled in the substrate . and the connectorprotrudes outside the ground plane, thusnot making it completely planar for thicksubstrates .Probe fed Rectangular Microstrip Patch Antennafrom side view 11. 3-Aperture Coupled FeedIn this type of feed technique, the radiatingpatch and the microstrip feed line are separatedby the ground plane .Coupling between the patch and the feedline is made through a slot or an aperturein the ground plane.The coupling aperture is usually centered under the Aperture-coupled feedpatch, leading to lower cross polarization due tosymmetry of the configuration.The amount of coupling from the feed line to the patch is determined by the shape, sizeand location of the aperture. 12. 3.2 Project specificationsProject SpecsOperating Frequency : 1.575 GHzInput Impedance: 50 OhmVSWR: 2:1 @ 1.575 GHzPolarization: RHCPBandwidth: 3.8% (~60 MHz)SubstrateRT/Duroid (Rogers Corp.)e= 2.22h= 125 milstan d = 0.001 13. Simulation Results of a 1.575 GHz GPSReceiver Antenna DesignReturn Loss 14. VSWR PLOT2 D PATTERN 15. VHDLWhat does HDL stand for?HDL is short for Hardware Description Language(VHDL VHSIC Hardware Description Language)(Very High Speed Integrated Circuit) 16. Basic Form of VHDL Code Every VHDL design description consists of at leastone entity / architecture pair, or one entity with multiplearchitectures. The entity section is used to declare I/O ports of thecircuit. The architecture portion describes the circuitsbehavior. A behavioral model is similar to a black box. Standardized design libraries are included beforeentity declaration. 17. Standard Libraries Include library ieee; before entity declaration. ieee.std_logic_1164 defines a standard for designersto use in describing interconnection data types used inVHDL modeling. ieee.std_logic_arith provides a set of arithmetic,conversion, comparison functions for signed,unsigned, std_ulogic, std_logic, std_logic_vector. Ieee.std_logic_unsigned provides a set of unsignedarithmetic, conversion, and comparison functions forstd_logic_vector. 18. Entity Declaration An entity declaration describes the interface of the component. PORT clause indicates input and output ports. An entity can be thought of as a symbol for a component. 19. Port Declaration PORT declaration establishes the interface of theobject to the outside world. Three parts of the PORT declaration Name Any identifier that is not a reserved word. Mode In, Out, Inout, Buffer Data type Any declared or predefined datatype. Sample PORT declaration syntax: 20. Architecture Declaration Architecture declarations describe the operation of thecomponent. Many architectures may exist for one entity, but only one may beactive at a time. An architecture is similar to a schematic of the component. 21. Modeling Styles There are three modeling styles: Behavioral (Sequential) Data flow Structural 22. VHDL Hierarchy 23. Sequential vs Concurrent Statements VHDL provides two different types ofexecution: sequential and concurrent. Different types of execution are useful formodeling of real hardware. Supports various levels of abstraction. Sequential statements view hardware from aprogrammer approach. Concurrent statements are order-independentand asynchronous. 24. Behavioural Style 25. Data flow Style 26. Structural Style