"""
Base classes for electromagnetic field sources.
This module defines the base Source class and related utilities for
implementing various types of electromagnetic sources in FDTD simulations.
"""
from abc import ABC, abstractmethod
from typing import Optional
import numpy as np
from prismo.core.fields import ElectromagneticFields
from prismo.core.grid import YeeGrid
[docs]
class Source(ABC):
"""
Abstract base class for all electromagnetic sources.
Parameters
----------
center : Tuple[float, float, float]
Physical coordinates of the source center (x, y, z) in meters.
size : Tuple[float, float, float]
Physical dimensions of the source region (Lx, Ly, Lz) in meters.
For point sources, use (0, 0, 0).
name : str, optional
Name of the source for identification.
enabled : bool, optional
Flag to enable/disable the source, default=True.
"""
[docs]
def __init__(
self,
center: tuple[float, float, float],
size: tuple[float, float, float],
name: Optional[str] = None,
enabled: bool = True,
):
self.center = center
self.size = size
self.name = name or f"{self.__class__.__name__}_{id(self)}"
self.enabled = enabled
# Set during initialization by the simulation
self._grid: Optional[YeeGrid] = None
self._source_region: dict[str, np.ndarray] = {}
[docs]
def initialize(self, grid: YeeGrid) -> None:
"""
Initialize the source on a specific grid.
Parameters
----------
grid : YeeGrid
The grid on which to initialize the source.
"""
self._grid = grid
self._setup_source_region()
def _setup_source_region(self) -> None:
"""
Set up the source region in grid coordinates.
This method computes the grid indices where the source is applied.
"""
if self._grid is None:
raise RuntimeError("Source must be initialized with a grid first")
# Convert physical coordinates to grid indices
x_min, x_max, y_min, y_max, z_min, z_max = self._compute_source_region()
# Store source region indices for each field component
# Each source will implement how to use these indices
self._source_region = {
"Ex": self._grid.get_component_indices(
"Ex", x_min, x_max, y_min, y_max, z_min, z_max
),
"Ey": self._grid.get_component_indices(
"Ey", x_min, x_max, y_min, y_max, z_min, z_max
),
"Ez": self._grid.get_component_indices(
"Ez", x_min, x_max, y_min, y_max, z_min, z_max
),
"Hx": self._grid.get_component_indices(
"Hx", x_min, x_max, y_min, y_max, z_min, z_max
),
"Hy": self._grid.get_component_indices(
"Hy", x_min, x_max, y_min, y_max, z_min, z_max
),
"Hz": self._grid.get_component_indices(
"Hz", x_min, x_max, y_min, y_max, z_min, z_max
),
}
def _compute_source_region(self) -> tuple[int, int, int, int, int, int]:
"""
Compute the grid index bounds for the source region.
Returns
-------
Tuple[int, int, int, int, int, int]
Grid index bounds (x_min, x_max, y_min, y_max, z_min, z_max).
"""
if self._grid is None:
raise RuntimeError("Source must be initialized with a grid first")
# Get physical half-sizes
half_Lx = self.size[0] / 2
half_Ly = self.size[1] / 2
half_Lz = self.size[2] / 2
# Convert physical coordinates to grid indices
x_min, y_min, z_min = self._grid.point_to_index(
(
self.center[0] - half_Lx,
self.center[1] - half_Ly,
self.center[2] - half_Lz,
)
)
x_max, y_max, z_max = self._grid.point_to_index(
(
self.center[0] + half_Lx,
self.center[1] + half_Ly,
self.center[2] + half_Lz,
)
)
# Ensure we have at least one cell for point sources
if x_min == x_max:
x_max = x_min + 1
if y_min == y_max:
y_max = y_min + 1
if z_min == z_max and self._grid.is_3d:
z_max = z_min + 1
return x_min, x_max, y_min, y_max, z_min, z_max
[docs]
@abstractmethod
def update_fields(
self, fields: ElectromagneticFields, time: float, dt: float
) -> None:
"""
Update electromagnetic fields with source contribution.
Parameters
----------
fields : ElectromagneticFields
Electromagnetic fields to update.
time : float
Current simulation time in seconds.
dt : float
Time step in seconds.
"""
pass
[docs]
def disable(self) -> None:
"""Disable the source."""
self.enabled = False
[docs]
def enable(self) -> None:
"""Enable the source."""
self.enabled = True