Sources

EM source types and source time waveforms in WiTwin Maxwell

Overview #

Sources inject electromagnetic fields into the simulation domain. Every source takes an optional source_time waveform. If omitted, it defaults to a continuous wave (CW) at the simulation frequency.

Source Time Waveforms #

CW — Continuous Wave #

mw.CW(frequency=1.0e9, amplitude=1.0, phase=0.0)

Parameter	Default	Description
`frequency`	required	Frequency in Hz. Must be > 0
`amplitude`	`1.0`	Peak amplitude
`phase`	`0.0`	Initial phase in radians

GaussianPulse #

A Gaussian-modulated sinusoidal pulse. Suitable for broadband multi-frequency simulations.

mw.GaussianPulse(frequency=1.0e9, fwidth=0.25e9, amplitude=1.0, phase=0.0)

Parameter	Default	Description
`frequency`	required	Center frequency in Hz
`fwidth`	required	Frequency width (bandwidth) in Hz
`amplitude`	`1.0`	Peak amplitude
`phase`	`0.0`	Initial phase in radians
`delay`	`None`	Time delay in seconds. Defaults to `6 / (2π × fwidth)`

RickerWavelet #

A second-derivative Gaussian wavelet. Zero DC component, useful for seismic and acoustic simulations.

mw.RickerWavelet(frequency=1.0e9, amplitude=1.0)

Parameter	Default	Description
`frequency`	required	Peak frequency in Hz
`amplitude`	`1.0`	Peak amplitude
`delay`	`None`	Time delay. Defaults to `4 / (π × frequency)`

Source Types #

PointDipole #

A point electric dipole source at a fixed position.

mw.PointDipole(
    position=(0.0, 0.0, -0.06),
    polarization="Ez",
    width=0.04,
    source_time=mw.GaussianPulse(frequency=1.0e9, fwidth=0.25e9, amplitude=50.0),
)

Parameter	Default	Description
`position`	required	Source position `(x, y, z)`
`polarization`	`"Ez"`	Polarization direction. One of `"Ex"`, `"Ey"`, `"Ez"`, or a unit vector
`width`	`0.02`	Source width. Must be > 0
`profile`	`"gaussian"`	Spatial profile. One of `"gaussian"`, `"ideal"`
`source_time`	`None`	Source waveform. Defaults to `CW`
`name`	`None`	Optional source name

PlaneWave #

A uniform plane wave propagating in a given direction.

mw.PlaneWave(
    direction=(0.0, 0.0, 1.0),
    polarization=(1.0, 0.0, 0.0),
    source_time=mw.GaussianPulse(frequency=1.0e9, fwidth=0.25e9),
)

Parameter	Default	Description
`direction`	`(0, 0, 1)`	Propagation direction unit vector. Must be orthogonal to `polarization`
`polarization`	`(1, 0, 0)`	Polarization unit vector
`source_time`	`None`	Source waveform
`injection`	`"soft"`	Injection mode. `"soft"` or `TFSF(bounds=...)`
`injection_axis`	`None`	Injection axis override. One of `"x"`, `"y"`, `"z"`, or `None`
`name`	`None`	Optional source name

GaussianBeam #

A Gaussian beam focused at a given point.

mw.GaussianBeam(
    direction=(0.0, 0.0, 1.0),
    polarization=(1.0, 0.0, 0.0),
    beam_waist=0.5,
    focus=(0.0, 0.0, 0.0),
    source_time=mw.GaussianPulse(frequency=1.0e9, fwidth=0.25e9),
)

Parameter	Default	Description
`direction`	`(0, 0, 1)`	Propagation direction unit vector
`polarization`	`(1, 0, 0)`	Polarization unit vector. Must be orthogonal to `direction`
`beam_waist`	`0.5`	Beam waist radius. Must be > 0
`focus`	`(0, 0, 0)`	Focal point position
`source_time`	`None`	Source waveform
`injection`	`"soft"`	Injection mode. `"soft"` or `TFSF(bounds=...)`
`name`	`None`	Optional source name

ModeSource #

A modal source injecting a waveguide mode. Currently experimental.

mw.ModeSource(
    position=(0.0, 0.0, 0.0),
    size=(1.0, 1.0, 0.0),
    mode_index=0,
    direction="+",
    source_time=mw.CW(frequency=1.0e9),
)

Parameter	Default	Description
`position`	`(0, 0, 0)`	Source center position
`size`	`(1, 1, 0)`	Source plane size. Exactly one component must be zero to define the injection plane
`mode_index`	`0`	Mode index to inject. Must be >= 0
`direction`	`"+"`	Propagation direction. `"+"` or `"-"`
`polarization`	`"auto"`	Polarization axis. `"auto"`, `"Ex"`, `"Ey"`, `"Ez"`, or a unit vector
`source_time`	`None`	Source waveform

Note

ModeSource is available but marked experimental. Behavior may change in future releases.

TFSF — Total Field / Scattered Field #

Defines a total-field/scattered-field injection region for use with PlaneWave or GaussianBeam:

mw.PlaneWave(
    direction=(0.0, 0.0, 1.0),
    polarization=(1.0, 0.0, 0.0),
    injection=mw.TFSF(bounds=((-0.2, 0.2), (-0.2, 0.2), (-0.2, 0.2))),
)

Next Steps #

Monitors — record field data
Simulation — run the simulation