# Directivity Monitor
A Directivity Monitor is a far-field monitor that records antenna radiation characteristics in the frequency domain at specified observation angles.
This object corresponds to tidy3d.rf.DirectivityMonitor (opens new window).
# Name
name: Unique name for the monitor.
- Required field
# Geometry
Specification of the monitor region.
# Center + Size
Object definition through a center position and size.
center: Center of the monitor in x, y, and z-directions.
- Type: floating-point number
- Unit: m, mm (default unit), um
size: Size of the monitor in x, y, and z-directions.
- Type: floating-point number
- Unit: m, mm (default unit), um
- Constraint: greater than or equal to 0
- Required field
# Bounds
Object definition through minimum and maximum coordinate bounds.
min: Values of the x, y, and z coordinates defining the lower corner of the monitor.
max: Values of the x, y, and z coordinates defining the upper corner of the monitor.
- Type: floating-point number
- Unit: m, mm (default unit), um
- Required field
# Settings
# Frequency Points
freqs: Frequencies stored by the monitor.
Frequency points can be entered by range or as a custom list.
See Frequency Settings.
# Theta
theta: Elevation angle samples at which far-field radiation is evaluated.
Theta is measured with respect to the global z-axis, relative to the local origin. In the GUI, this setting is labeled as Elevation angle.
Theta values can be entered by range or as a custom list.
See Theta Settings.
# Phi
phi: Azimuth angle samples at which far-field radiation is evaluated.
Phi is measured around the global z-axis, relative to the local origin. In the GUI, this setting is labeled as Azimuth angle.
Phi values can be entered by range or as a custom list.
See Phi Settings.
# Advanced
custom_origin: Local origin used for defining observation points.
- Type: three floating-point numbers
- Unit: m, mm (default unit), um
- Default: monitor center
medium: Medium through which fields are projected.
- Default: use the same medium as the monitor location
colocate: Defines whether fields are colocated to grid cell boundaries.
- Default: True
- The Directivity Monitor API hard-codes this value to True.
exclude_surfaces: Surfaces excluded from integration when the monitor is a volume.
- Options: x-/x+/y-/y+/z-/z+
- Default: None
interval_space: Number of grid step intervals at which near fields are recorded for far-field projection in x, y, and z-directions.
- Type: three positive integers
- Default: (1, 1, 1)
When a value is greater than 1, the monitor grid is downsampled in that direction, while the first and last grid points are still included.
apodization: Optional apodization window applied when transforming time-domain fields into frequency-domain data.