HFSS using FEM
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HFSSIt’s capabilities and mechanism
Y.SAI KRISHNA SAKETH
DEPT. OF ECE,NMIT
HFSS CAPABILITIES AND MECHANISMWHAT IS HFSS?
HFSS IS AN ACRONYM OF HIGH FREQUENCY STRUCTURAL SIMULATOR.
ANSYS HFSS software is the industry standard for simulating 3-D full-wave electromagnetic fields. Its standard accuracy, advanced solver and high-performance computation technology have made it an essential tool for engineers doing accurate and rapid design of high-frequency and high-speed electronic components.
Potential of HFSS• HFSS utilizes a 3-D full-wave frequency domain electromagnetic field solver based on the
finite element method (FEM) to compute the electrical behavior of components.
• With HFSS, engineers can extract s, y, z parameters, visualize 3-d electromagnetic local, near-and far-field, and generate models to evaluate signal quality, including transmission path losses, reflection loss due to impedance mismatches, parasitic coupling and radiation.
• HFSS offers multiple state-of the-art solver technologies based on finite element, integral equations.
How HFSS works ?
• HFSS software utilizes tetrahedral mesh elements to determine a solution to a given electromagnetic problem.
• These mesh elements in combination with the adaptive mesh procedure create a geometrically conformal, and electromagnetically appropriate, mesh for any arbitrary hfss simulation.
• In HFSS traditional approach for simulating large phased-array antennas is to approximate antenna behavior by assuming an infinitely large array. In this technique, one or more antenna elements are placed within a unit cell with periodic boundary conditions on the surrounding walls that mirror the fields to create an infinite number of images in two directions.
Sample mesh analysis by HFSS
When viewed in 3-dimention,they are tetrahedral divisions on arbitrary element considered.
Basic Mechanism and Approach
THE NUMERICAL APPROXIMATION OF MAXWELL’S EQUATIONS, COMPUTATIONAL ELECTROMAGNETICS (CEM), HAS EMERGED AS A CRUCIAL ENABLING TECHNOLOGY FOR RADIO-FREQUENCY, MICROWAVE, AND WIRELESS ENGINEERING.
COMMERCIAL OR PUBLIC DOMAIN CODES IMPLEMENTING THESE METHODS ARE THEN APPLIED TO COMPLEX, REAL-WORLD ENGINEERING PROBLEMS AND A CAREFUL ANALYSIS OF THE RELIABILITY OF THE RESULTS OBTAINED IS PERFORMED.
THE THREE MOST POPULAR “FULL-WAVE” METHODS
The Finite Difference Time Domain Method(FDTM).
The Method of Moments(M.O.M)
The Finite Element Method(FEM).
Strengths and weaknesses of CEM methodsGENERAL CHARACTERSTICS IF THE ABOVE METHODS ARE IMPLEMENTED FOR OPEN REGION PROBLEMS.
Strengths and weaknesses of CEM methods
GENERAL CHARACTERSTICS IF THE ABOVE METHODS ARE IMPLEMENTED FOR OPEN REGION PROBLEMS.
Finite Element Method• The finite element method (FEM) is a standard tool for solving differential equations in
many disciplines, for example in Electromagnetics, solid and structural mechanics, fluid dynamics, acoustics, and thermal conduction.
• The finite element method (fem) has been widely used in structural mechanics and thermodynamics; its first application in the modern form dates to the 1950s, although its mathematical roots are older, and the first application in electromagnetics was undertaken in the late 1960.
• It is assumed that they are connected in a finite number of nodal points.
WHEN STRUCTURE MARKED BY NODES
• FEM USES MESHES WHICH MAY CONSIST OF TRIANGLES IN TWO DIMENSIONS AND TETRAHEDRONS IN THREE DIMENSIONS, FOR EXAMPLE TETRAHEDRAL ORIENTATION GIVE SCOPE TO REPRESENT CURVED OBJECTS.
• IN DETAIL, FEM CUTS A STRUCTURE INTO SEVERAL ELEMENTS (PIECES OF THE STRUCTURE).
• THEN RECONNECTS ELEMENTS AT “NODES” AS IF NODES WERE PINS OR DROPS OF GLUE THAT HOLD ELEMENTS TOGETHER.
• THIS PROCESS RESULTS IN A SET OF SIMULTANEOUS ALGEBRAIC EQUATIONS.
Different elements in HFSS• DIFFERENT ELEMENTS SHAPES AS FOLLOWS
1. A LINE IN ONE DIMENSION.
2. A TRIANGLE AND SQUARE IN TWO DIMENSIONS.
3. A TETRAHEDRON, PRISM, PYRAMID, AND CUBE IN THREE DIMENSIONS.
• The unknown field is discretized using a finite element mesh; typically, triangular elements are used for surface meshes and tetrahedrons for volumetric meshes, although many other types of elements are available.
• Another nice property of the fem is that the method provides a well-defined representation of the sought function everywhere in the solution domain. This makes it possible to apply many mathematical tools and prove important properties concerning stability and convergence.
• The FEM handles inhomogeneous materials and complex geometries with aplomb.
Overview of the Finite Element Method
Merits of fem1. VERY STRAIGHT FORWARD TREATMENT OF COMPLEX GEOMETRIES AND MATERIAL
2. VERY SIMPLE HANDLING OF DISPERSIVE MATERIALS (I.E. MATERIALS WITH FREQUENCY-DEPENDENT PROPERTIES).
3. ABILITY TO HANDLE EIGEN PROBLEMS AND HIGHER ORDER P.D.E WITH STABILITY.
4. STRAIGHT FORWARD EXTENSION TO HIGHER-ORDER BASIS FUNCTIONS. THE FEM LENDS ITSELF TO THE USE OF HIGHER-ORDER BASIS FUNCTIONS AND ANALYSIS.
Merits of fem5. “MULTI-PHYSICS” POTENTIAL – THIS MEANS THE ABILITY TO COUPLE EM SOLUTIONS WITH, FOR IN- STANCE, MECHANICAL OR THERMAL SOLUTIONS.
6. DUE NO DOUBT TO THE WIDESPREAD POPULARITY AND MATURITY OF THE FEM IN
OTHER fiELDS OF ENGINEERING. IT IS PROBABLY ONLY SIGNIfiCANT IN HIGH- POWER APPLICATIONS, WHERE THERMAL EFFECTS CAN BE IMPORTANT – EITHER DESIRED, AS IN THE CASE OF MICROWAVE DIELECTRIC HEATING, OR UNDESIRED, SUCH AS WITH HIGH-POWER TRANSMITTER DESIGN.