Monitors

Monitor types for field and flux recording in WiTwin Maxwell

Overview #

Monitors record field data during simulation. Add them to the scene before running:

scene.add_monitor(mw.PointMonitor("probe", (0.0, 0.0, 0.06), fields=("Ez",)))

After the simulation, read monitor data from the result:

data = result.monitor("probe")["data"]

PointMonitor #

Records field components at a single point.

mw.PointMonitor(
    name="probe",
    position=(0.0, 0.0, 0.06),
    fields=("Ez",),
)

Parameter	Default	Description
`name`	required	Unique monitor name
`position`	required	Recording point `(x, y, z)`
`fields`	`("Ez",)`	Field components to record. Any of `"Ex"`, `"Ey"`, `"Ez"`, `"Hx"`, `"Hy"`, `"Hz"`

PlaneMonitor #

Records field components over an infinite axis-aligned plane.

mw.PlaneMonitor(
    name="field_slice",
    axis="z",
    position=0.0,
    fields=("Ez",),
    frequencies=[1.0e9],
)

Parameter	Default	Description
`name`	required	Unique monitor name
`axis`	`"z"`	Normal axis of the recording plane
`position`	`0.0`	Position along the normal axis
`fields`	`("Ez",)`	Field components to record
`frequencies`	`None`	Frequencies to record at. Records all if `None`
`compute_flux`	`False`	Compute Poynting flux through the plane
`normal_direction`	`"+"`	Normal direction for flux. `"+"` or `"-"`

FluxMonitor #

A convenience wrapper around PlaneMonitor that automatically selects the correct tangential field components for flux computation.

mw.FluxMonitor(
    name="flux",
    axis="z",
    position=0.0,
    frequencies=[1.0e9],
)

Parameter	Default	Description
`name`	required	Unique monitor name
`axis`	`"z"`	Normal axis
`position`	`0.0`	Position along the normal axis
`frequencies`	`None`	Frequencies to record at
`normal_direction`	`"+"`	Normal direction for flux

FinitePlaneMonitor #

Records field components over a finite axis-aligned plane with explicit position and size.

mw.FinitePlaneMonitor(
    name="face",
    position=(0.0, 0.0, 0.1),
    size=(0.5, 0.5, 0.0),
    fields=("Ex", "Ey", "Hx", "Hy"),
    frequencies=[1.0e9],
    compute_flux=True,
    normal_direction="+",
)

Parameter	Default	Description
`name`	required	Unique monitor name
`position`	`(0, 0, 0)`	Center position. The zero-size axis defines the plane normal
`size`	`(1, 1, 0)`	Plane size. Exactly one component must be zero
`fields`	`("Ez",)`	Field components to record
`frequencies`	`None`	Frequencies to record at
`compute_flux`	`False`	Compute Poynting flux. Requires all tangential field components
`normal_direction`	`"+"`	Normal direction for flux

ClosedSurfaceMonitor #

A closed surface composed of FinitePlaneMonitor faces for computing total radiated power.

# Convenience box constructor
monitor = mw.ClosedSurfaceMonitor.box(
    "power",
    position=(0.0, 0.0, 0.0),
    size=(0.4, 0.4, 0.4),
    frequencies=[1.0e9],
)
scene.add_monitor(monitor)

Or construct manually from faces:

mw.ClosedSurfaceMonitor(
    name="power",
    faces=[face_x_neg, face_x_pos, face_y_neg, face_y_pos, face_z_neg, face_z_pos],
    frequencies=[1.0e9],
)

Note

ClosedSurfaceMonitor requires balanced face areas — each axis must have equal positive and negative face areas. Use ClosedSurfaceMonitor.box() to avoid area balance errors.

ModeMonitor #

Records modal overlap at a waveguide cross-section. Currently experimental.

mw.ModeMonitor(
    name="mode",
    position=(0.0, 0.0, 0.0),
    size=(1.0, 1.0, 0.0),
    mode_index=0,
    direction="+",
    frequencies=[1.0e9],
)

Parameter	Default	Description
`name`	required	Unique monitor name
`position`	`(0, 0, 0)`	Monitor center position
`size`	`(1, 1, 0)`	Monitor plane size. Exactly one component must be zero
`mode_index`	`0`	Mode index to record. Must be >= 0
`direction`	`"+"`	Propagation direction. `"+"` or `"-"`
`frequencies`	`None`	Frequencies to record at

Note

ModeMonitor is available but marked experimental.

Next Steps #

Materials — material models and dispersive media
Simulation — run the simulation