Tutorial HFSS - Modelagem e simulação, Manuais, Projetos, Pesquisas de Eletromagnetismo

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Ansys High Frequency Structure

Simulator (HFSS) Tutorial

MARK JONES

PACIFIC NORTHWEST NATIONAL LABORATORY

Agenda

Overview of HFSS

Capabilities and key features Example measurement comparisons

Cylindrical cavity tutorial

Eigenmode solver Parametric geometry Curvilinear elements Modal frequencies, Q-factors, and fields Field calculator

Dipole antenna tutorial

Driven excitation solver Radiation boundaries Frequency sweep S-parameters, near and far fields

HFSS User Interface Project Manager Properties Message Manager Progress Window 3D Model Editor Graphics Toolbars 3D Model Editor Tree

Solution Types

Eigenmode solution

Solves for natural resonances of structure based on geometry, materials, and boundaries Provides modal frequencies, unloaded Q- factors, and fields

Driven solution

Port or incident field used to excite the structure Driven modal method commonly used for RF/microwave designs Driven terminal method commonly used for multi-conductor transmission lines Provides S-parameters and fields

Port Excitations

Wave ports

2D FEM solver calculates requested number of modes (treated as t-line cross-section) Solves for impedances and propagation constants Supports multiple modes and de-embedding Simple for closed t-lines Must allow room for fields of open t-lines Must touch external boundary or backed by conducting object

Lumped ports

User-assigned constant impedance Uniform electric field on surface Single TEM mode with no de-embedding Can be internal to model

Boundary Conditions

Used to simplify geometry or make

meshing more efficient

Material properties for surfaces

Finite conductivity (imperfect conductor) Perfect electric or magnetic conductor

Surface approximations for components

Lumped RLC Layered impedance

Radiation

Absorbing boundary condition Perfectly matched layers (PML)

Any object surface that touches the

background is automatically defined as

Perfect E boundary

Example Comparison with Measurement

Cavity-backed Archimedean spiral antenna with tapered line balun

Example Comparisons with Measurement

Curvilinear Mesh Elements

Global mesh approximation setting

for all true surfaces in model

Higher order (curvilinear) elements

used to represent the geometry

Pulls midpoints of tetrahedra surfaces to true surface

Pillbox resonator with analytical fR =

22.950 GHz for TM 010 mode

Default setting: 23.269 GHz Finer segmentation: 23.012 GHz Curvilinear elements: 22.950 GHz 6024 DOF 1.38% error 6140 DOF 0.03% error 4966 DOF 0.00% error

FEM Solver

Direct matrix solver is default technique

Exactly solves matrix equation Ax = b Multi-frontal sparse matrix solver to find inverse of A (LU decomposition) Solves for all excitations b simultaneously

Iterative matrix solver is optional technique

for driven solutions

Reduces RAM usage and often runtime Solves matrix equation Max = Mb where M is preconditioner Begins with initial solution and recursively updates solution until tolerance is reached Iterates for each excitation b More sensitive to mesh quality, reverts to direct solver if it fails to converge

∇× = +

∇× = −

B

D

t

D

H J

t

B

E

ρ

Fields Calculator Tool for performing math operations on saved fields E, H, J, and Poynting data available Geometric, complex, vector, and scalar data Perform operations using model or non-model geometry Generate numerical, graphical, geometrical, or exportable data Reverse Polish notation Frequently used expressions can be included in user library and loaded into any project Eliminates need to re-create expressions used across projects Data stack Stack operations Context selection Named expressions Calculator functions ∫∫ × • s Re{ E H *} ds 2 1 ∫∫∫ v E dv 2 | | 2 1 σ

Keyboard Shortcuts

Cylindrical Cavity Example

Empty copper cavity

Radius = 21 cm Height = 100 cm

Expected results for TM 010 mode

fR = 546.42 MHz Q-factor = 61,391 (Li and Jiang, 2006) Form factor C = 0.69 (Peng et al. , 2000) Form factor C = 0.692 (Stern et al. , 2015) ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛

= δ R R H H Qu

1: Create HFSS Project

Insert into Electronics Desktop using Project > Insert HFSS Design