tidy3d.DirectivityMonitor

tidy3d.DirectivityMonitor#

class DirectivityMonitor[source]#

Bases: FieldProjectionAngleMonitor, FluxMonitor

Monitor that records the radiation characteristics of antennas in the frequency domain at specified observation angles.

Parameters:

  • attrs (dict = {}) – Dictionary storing arbitrary metadata for a Tidy3D object. This dictionary can be freely used by the user for storing data without affecting the operation of Tidy3D as it is not used internally. Note that, unlike regular Tidy3D fields, attrs are mutable. For example, the following is allowed for setting an attr obj.attrs['foo'] = bar. Also note that Tidy3D` will raise a TypeError if attrs contain objects that can not be serialized. One can check if attrs are serializable by calling obj.json().

  • center (Union[tuple[Union[float, autograd.tracer.Box], Union[float, autograd.tracer.Box], Union[float, autograd.tracer.Box]], Box] = (0.0, 0.0, 0.0)) – [units = um]. Center of object in x, y, and z.

  • size (Union[tuple[Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box], Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box], Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box]], Box]) – [units = um]. Size in x, y, and z directions.

  • name (ConstrainedStrValue) – Unique name for monitor.

  • interval_space (Tuple[PositiveInt, PositiveInt, PositiveInt] = (1, 1, 1)) – Number of grid step intervals at which near fields are recorded for projection to the far field, along each direction. If equal to 1, there will be no downsampling. If greater than 1, the step will be applied, but the first and last point of the monitor grid are always included. Using values greater than 1 can help speed up server-side far field projections with minimal accuracy loss, especially in cases where it is necessary for the grid resolution to be high for the FDTD simulation, but such a high resolution is unnecessary for the purpose of projecting the recorded near fields to the far field.

  • colocate (Literal[True] = True) – Defines whether fields are colocated to grid cell boundaries (i.e. to the primal grid). Can be toggled for field recording monitors and is hard-coded for other monitors depending on their specific function.

  • freqs (Union[Tuple[float, ...], ArrayLike[dtype=float, ndim=1]]) – [units = Hz]. Array or list of frequencies stored by the field monitor.

  • apodization (ApodizationSpec = ApodizationSpec(attrs={}, start=None, end=None, width=None, type='ApodizationSpec')) – Sets parameters of (optional) apodization. Apodization applies a windowing function to the Fourier transform of the time-domain fields into frequency-domain ones, and can be used to truncate the beginning and/or end of the time signal, for example to eliminate the source pulse when studying the eigenmodes of a system. Note: apodization affects the normalization of the frequency-domain fields.

  • normal_dir (Optional[Literal['+', '-']] = None) – Direction of the surface monitor’s normal vector w.r.t. the positive x, y or z unit vectors. Must be one of '+' or '-'. Applies to surface monitors only, and defaults to '+' if not provided.

  • exclude_surfaces (Optional[Tuple[Literal['x-', 'x+', 'y-', 'y+', 'z-', 'z+'], ...]] = None) – Surfaces to exclude in the integration, if a volume monitor.

  • custom_origin (Optional[Tuple[float, float, float]] = None) – [units = um]. Local origin used for defining observation points. If None, uses the monitor’s center.

  • far_field_approx (bool = True) – Whether to enable the far field approximation when projecting fields. If True, terms that decay as O(1/r^2) are ignored, as are the radial components of fields. Typically, this should be set to True only when the projection distance is much larger than the size of the device being modeled, and the projected points are in the far field of the device.

  • window_size (Tuple[NonNegativeFloat, NonNegativeFloat] = (0, 0)) – Size of the transition region of the windowing function used to ensure that the recorded near fields decay to zero near the edges of the monitor. The two components refer to the two tangential directions associated with each surface. For surfaces with the normal along x, the two components are (y, z). For surfaces with the normal along y, the two components are (x, z). For surfaces with the normal along z, the two components are (x, y). Each value must be between 0 and 1, inclusive, and denotes the size of the transition region over which fields are scaled to less than a thousandth of the original amplitude, relative to half the size of the monitor in that direction. A value of 0 turns windowing off in that direction, while a value of 1 indicates that the window will be applied to the entire monitor in that direction. This field is applicable for surface monitors only, and otherwise must remain (0, 0).

  • medium (Union[Medium, AnisotropicMedium, PECMedium, PoleResidue, Sellmeier, Lorentz, Debye, Drude, FullyAnisotropicMedium, CustomMedium, CustomPoleResidue, CustomSellmeier, CustomLorentz, CustomDebye, CustomDrude, CustomAnisotropicMedium, PerturbationMedium, PerturbationPoleResidue, LossyMetalMedium, Medium2D, AnisotropicMediumFromMedium2D] = None) – Medium through which to project fields. Generally, the fields should be projected through the same medium as the one in which this monitor is placed, and this is the default behavior when medium=None. A custom medium can be useful in some situations for advanced users, but we recommend trying to avoid using a non-default medium.

  • proj_distance (float = 1000000.0) – [units = um]. Radial distance of the projection points from local_origin.

  • theta (Union[Tuple[float, ...], ArrayLike[dtype=float, ndim=1]]) – [units = rad]. Polar angles with respect to the global z axis, relative to the location of local_origin, at which to project fields.

  • phi (Union[Tuple[float, ...], ArrayLike[dtype=float, ndim=1]]) – [units = rad]. Azimuth angles with respect to the global z axis, relative to the location of local_origin, at which to project fields.

Note

For directivity, the computation is based on the ratio of the radiation intensity in a given direction to the average radiation intensity over all directions:

Balanis, Constantine A., “Antenna Theory: Analysis and Design,” John Wiley & Sons, Chapter 2.6 (2016).

For axial ratio, the computation is based on:

Balanis, Constantine A., “Antenna Theory: Analysis and Design,” John Wiley & Sons, Chapter 2.12 (2016).

Attributes

attrs

Methods

storage_size(num_cells, tmesh)

Size of monitor storage given the number of points after discretization.

Inherited Common Usage

storage_size(num_cells, tmesh)[source]#

Size of monitor storage given the number of points after discretization.

__hash__()#

Hash method.