6. Electromagnetics Enhancements. Training Manual 001419 15 Aug 2000 6-2 Electromagnetics Enhancements Emag focus in ANSYS 5.7 is on high-frequency electromagnetics

6. Electromagnetics Enhancements

Training Manual 00141915 Aug 2000

6-2

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.7Electromagnetics Enhancements

• Emag focus in ANSYS 5.7 is on high-frequency electromagnetics (discussed next).

• Other Emag enhancements:

– LMATRIX (inductance calculation) improvements• Output array contains the NxN inductance matrix (as before)

and a new N+1th column containing flux linkage values, with the I th row corresponding to the I th coil.

– SENERGY (magnetic energy calculation) is more robust, accurate, and faster.


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.7… Electromagnetics Enhancements

• Other Emag enhancements (cont'd):

– New diode element, CIRCU125• To simulate a common or Zener diode.

• Can interface with circuit element CIRCU124, transducer element TRANS126, and mechanical elements MASS21, COMBIN14, and COMBIN39 for coupled-field analyses.

• Can be defined using the circuit builder.

CIRCU125


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.7High Frequency Electromagnetics

Overview

• In ANSYS, HF Electromagnetics is used to simulate the full wave electromagnetic phenomena.

– RF/microwave problems (interior wave propagation)

– Radiation and scattering problems (exterior wave propagation)

• Available in ANSYS/Multiphysics and ANSYS/Emag HF products.

• HF solution is in the frequency domain.

• No limit on the highest frequency allowed.


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.7

… High Frequency Electromagnetics

Overview (cont'd)

Major components of a HF FEA model

HF PostprocessingExcitations

materials

Boundaryconditions

Modal analysis

Harmonic analysis

CAD import

New/enhancedExisting

HF Elements


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.7… High Frequency Electromagnetics

Overview (cont'd)

• ANSYS 5.7 takes a major leap in HF simulation capabilities with several new features and enhancements:

– New boundary conditions• PML (perfectly matched layer), impedance

– New excitations• Waveguide ports; plane wave; surface magnetic field, surface

electric field, and current density excitations

– Elements• New HF118 element, enhancements to HF119 & HF120

– Solvers and postprocessing


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.7HF Electromagnetics - New BC's

PML

Perfectly Matched Layer (PML)

• Absorbing layers of elements used for the truncation of the HF FEA domain.

• Reduce the FEA domain significantly by replacing the outer computation domain (infinite) with an absorbing layers.

• Required in many real world applications:

– Exterior phenomena, e.g, antenna and EMC/EMI problems.

– Interior phenomena, e.g, waveguides and transmission lines.


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… PML

• PML region is simply a layer (or layers) of elements placed at the boundary of the field domain.

• Elements used are 119 and 120 with KEYOPT(4) = 1. For example: ET,2,HF120,,,,1

– Extend the material properties in the field region into PML

– PML supports symmetry boundary conditions

PML

Surrounding field

HF Device Schematic of cross sectionof a 3D PML region


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… PML

• Recommendations:– PML boundary edges should be parallel to global Cartesian or Cartesian

ESYS.

– Thickness of PML region > 0.25*wavelength.

– Allow at least 4-5 layers of elements in surrounding field as buffer zone between device and PML.

– Four elements through the thickness of PML region for - 50 Db attenuation. More attenuation can be obtained by adding more PML layers.

PML1

PML2

PML3ESYS1

ESYS2

ESYS3

Schematic of1D PML layers

PML1

PML2

PML3ESYS1

ESYS2


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Impedance

• Four types of impedance BC's are now available:

– Far-field radiation boundary

– Air-dielectric boundary

– PEC (perfect electric conductor) surface with dielectric coating

– Non-PEC surface

• Apply using SF family of commands

dielectric

air-dielectricInterface

air

far-field boundary

PEC with dielectric coating

non-perfect conductor

surface of non-perfectconductor

conductor


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.7HF Electromagnetics - New Excitations

Waveguide Ports

• New parallel-plate waveguide

– Can be used to simulate problems like micro-strip.

• All four types of waveguides

– Z axis can be in either the wave propagation direction or the opposite direction. X-axis must be parallel to width of port.

– Origin for rectangular waveguide is at center, different from 5.6.

x

y

zRectangular Waveguide

Parallel-PlateWaveguide

CircularWaveguide

Coax Waveguide

new

x

y

x

y

x

y

z

x

y

z


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...Waveguide Ports

• Higher-order modes are now available at 5.7:

COAX RECT CIRC PARA

TEM TEM

TEmn TEmn TE0n

TMmn TMmn TM0n


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...Waveguide Ports

• HFPORT,Portnum,Porttype,Local,Mode,Portbc,VAL1,VAL2,VAL3,VAL4,VAL5

• New HFPORT command replaces PORTOPT.

• Port boundary conditions by Portbc in HFPORT:

– IMPD Matching the impedance of the single mode.

– SEXT Terminating the port w/ PML layers. An invisible port to extract S-parameters.

– SOFT Equivalent current excitation. Allow multiple ports & multiple modes. Can extract S-parameter.

– HARD Fixed electromagnetic field at port.


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...Waveguide Ports

• Schematics of four Portbc options for waveguides in HFPORT command

portSEXTport IMPD

HARDincident waveincident waveincident wave

reflection wave reflection wave

SOFT

incident wave

PML2

PML1


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Plane Wave

• New PLWAVE command replaces PLANEWAVE:

– PLWAVE, EX, EY, EZ, AngX, AngZ• EX, EY and EZ are the electric field amplitudes in X, Y and Z

directions.

• AngX and AngZ are the angles of the wave to X-axis and Z-axis.

– Used for scattering analysis in EMC/EMI analysis


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Source Terms

• You can now specify the following excitation sources (using the BF family of commands):

– Magnetic field (H) at a surface.

– Electric field (EF) at a surface.

– Current density (JS) at a point, line, surface, or volume.


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.7HF Electromagnetics

Element Enhancements

• New 2.5-D, 8-node HF118 element

– Extract eigenvalues of guided wave structures (waveguides or transmission lines).

– Applicable for modal analyses (Block Lanczos).

– Quadrilateral or triangular shapes.

– Both 1st order and 2nd order available.

– To calculate cutoff frequencies and propagating constants used together with HFEIGOPT.


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… Element Enhancements

• HF119 (10-node tet) gets new 2nd-order option

– Applicable to both modal and full harmonic analyses

– Keyopt(1) = 2

– Better accuracy compared with 1st order element, especially for complex geometry

• HF120 (20-node brick) gets improved 2nd-order option

– DOFs from 36/element to 54/element

– Complete vector basis functions

– Better accuracy for higher-order modes


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Solution and Postprocessing

• Sparse solver is now the default (not frontal).

– ICCG and FRONTAL also available as before

• Choosing analysis types

– Harmonic analysis (Antype, harmic)HFSCAT,SCAT must be specified for RCS calculation

– Modal analysis (Antype,modal) 3D or 2D modal analysis


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… Solution and Postprocessing

• New commands to review far-field results:

– PLHFFAR to display the electromagnetic far field, radar cross-section (RCS), and antenna pattern (PATT)

– PRHFFAR for listings

RCS of a metal plate with incident plane wave


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… Solution and Postprocessing

• New HFNEAR command to calculate near-field results (EF & H).

– Options to calculate at a specified point or along a path.

• New PRHFFAR calculates/prints far field beyond FEA domain.

• Other:

– HFSYM to set symmetry planes for postprocessing calculations in near and far field

– Current density can be shown graphically

– Calculated parameters:• SPARM: magnitude and phase angle of S-parameter (both

single and multiple ports)

Documents

6. Electromagnetics Enhancements. Training Manual 001419 15 Aug 2000 6-2 Electromagnetics Enhancements Emag focus in ANSYS 5.7 is on high-frequency electromagnetics