6. Electromagnetics
Enhancements
Electromagnetics Enhancements
• Emag focus in ANSYS 5.7 is on high-frequency
electromagnetics (discussed next).
– 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.
NEW FEATURES 5.7
• Other Emag enhancements:
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… Electromagnetics Enhancements
• Other Emag enhancements (cont'd):
– New diode element, CIRCU125
• To simulate a common or Zener diode.
• Can be defined using the circuit builder.
CIRCU125
NEW FEATURES 5.7
• Can interface with circuit element CIRCU124, transducer element
TRANS126, and mechanical elements MASS21, COMBIN14, and
COMBIN39 for coupled-field analyses.
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High Frequency Electromagnetics
Overview
– RF/microwave problems (interior wave propagation)
– Radiation and scattering problems (exterior wave
propagation)
• Available in ANSYS/Multiphysics and
ANSYS/Emag HF products.
NEW FEATURES 5.7
• In ANSYS, HF Electromagnetics is used to simulate
the full wave electromagnetic phenomena.
• HF solution is in the frequency domain.
• No limit on the highest frequency allowed.
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… High Frequency Electromagnetics
Overview (cont'd)
Major components of a HF FEA model
Modal analysis
CAD import
Boundary
conditions
HF Elements
New/enhanced
Existing
NEW FEATURES 5.7
Harmonic analysis
materials
HF Postprocessing
Excitations
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… High Frequency Electromagnetics
Overview (cont'd)
– New boundary conditions
• PML (perfectly matched layer), impedance
– New excitations
• Waveguide ports; plane wave; surface magnetic field, surface
electric field, and current density excitations
NEW FEATURES 5.7
• ANSYS 5.7 takes a major leap in HF simulation
capabilities with several new features and
enhancements:
– Elements
• New HF118 element, enhancements to HF119 & HF120
– Solvers and postprocessing
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HF Electromagnetics - New BC's
PML
Perfectly Matched Layer (PML)
• 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.
NEW FEATURES 5.7
• Absorbing layers of elements used for the
truncation of the HF FEA domain.
– Interior phenomena, e.g, waveguides and transmission
lines.
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HF Electromagnetics - New BC's
… PML
• PML region is simply a layer (or layers) of elements
placed at the boundary of the field domain.
– Extend the material properties in the field region into PML
– PML supports symmetry boundary conditions
PML
Surrounding field
HF Device
NEW FEATURES 5.7
• Elements used are 119 and 120 with KEYOPT(4) = 1.
For example: ET,2,HF120,,,,1
Schematic of cross section
of a 3D PML region
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HF Electromagnetics - New BC's
… PML
• Recommendations:
– 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.
PML2
NEW FEATURES 5.7
– PML boundary edges should be parallel to global Cartesian
or Cartesian ESYS.
ESYS2
PML1
Schematic of
1D PML layers
ESYS1
PML3
ESYS3
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HF Electromagnetics - New BC's
Impedance
• Four types of impedance BC's are now available:
– Far-field radiation boundary
– PEC (perfect electric conductor) surface with dielectric coating
– Non-PEC surface
• Apply using SF family of commands
air-dielectric
Interface
surface of
non-perfect
conductor
dielectric
non-perfect
conductor
conductor
PEC with
dielectric coating
NEW FEATURES 5.7
– Air-dielectric boundary
air
far-field
boundary
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HF Electromagnetics - New Excitations
Waveguide Ports
• New parallel-plate waveguide
– Can be used to simulate problems like micro-strip.
– 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.
new
y
y
x
z
Rectangular
Waveguide
y
y
x
x
NEW FEATURES 5.7
• All four types of waveguides
x
z
Parallel-Plate
Waveguide
Circular
Waveguide
Coax
Waveguide
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HF Electromagnetics - New Excitations
...Waveguide Ports
• Higher-order modes are now available at 5.7:
RECT
C IR C
TEM
P AR A
TEM
TEm n
TEm n
TE0n
TM m n
TM m n
TM 0n
NEW FEATURES 5.7
CO AX
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HF Electromagnetics - New Excitations
...Waveguide Ports
• HFPORT,Portnum,Porttype,Local,Mode,Portbc,
VAL1,VAL2,VAL3,VAL4,VAL5
• 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.
NEW FEATURES 5.7
• New HFPORT command replaces PORTOPT.
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HF Electromagnetics - New Excitations
...Waveguide Ports
• Schematics of four Portbc options for waveguides
in HFPORT command
port
PML2
PML1
IMPD
port
incident wave
SOFT
HARD
incident wave
reflection wave
incident wave
incident wave
NEW FEATURES 5.7
SEXT
reflection wave
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HF Electromagnetics - New Excitations
Plane Wave
• New PLWAVE command replaces PLANEWAVE:
– PLWAVE, EX, EY, EZ, AngX, AngZ
• AngX and AngZ are the angles of the wave to X-axis and Zaxis.
– Used for scattering analysis in EMC/EMI analysis
NEW FEATURES 5.7
• EX, EY and EZ are the electric field amplitudes in X, Y and Z
directions.
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HF Electromagnetics - New Excitations
Source Terms
• You can now specify the following excitation sources (using
the BF family of commands):
– Magnetic field (H) at a surface.
– Current density (JS) at a point, line, surface, or volume.
NEW FEATURES 5.7
– Electric field (EF) at a surface.
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HF Electromagnetics
Element Enhancements
• New 2.5-D, 8-node HF118 element
– 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.
NEW FEATURES 5.7
– Extract eigenvalues of guided wave structures (waveguides
or transmission lines).
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HF Electromagnetics
… Element Enhancements
• HF119 (10-node tet) gets new 2nd-order option
– Applicable to both modal and full harmonic analyses
– 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
NEW FEATURES 5.7
– Keyopt(1) = 2
– Better accuracy for higher-order modes
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HF Electromagnetics
Solution and Postprocessing
• Sparse solver is now the default (not frontal).
– ICCG and FRONTAL also available as before
– Harmonic analysis (Antype, harmic)
HFSCAT,SCAT must be specified for RCS calculation
– Modal analysis (Antype,modal)
3D or 2D modal analysis
NEW FEATURES 5.7
• Choosing analysis types
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HF Electromagnetics
… Solution and Postprocessing
• New commands to review far-field results:
– PRHFFAR for listings
RCS of a
metal plate
with incident
plane wave
NEW FEATURES 5.7
– PLHFFAR to display the electromagnetic far field, radar
cross-section (RCS), and antenna pattern (PATT)
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HF Electromagnetics
… Solution and Postprocessing
• New HFNEAR command to calculate near-field
results (EF & H).
• New PRHFFAR calculates/prints far field beyond
FEA domain.
• Other:
– HFSYM to set symmetry planes for postprocessing
calculations in near and far field
NEW FEATURES 5.7
– Options to calculate at a specified point or along a path.
– Current density can be shown graphically
– Calculated parameters:
• SPARM: magnitude and phase angle of S-parameter (both
single and multiple ports)
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