def grid():
grid = fdtd.Grid(
shape=(10, 10, 10),
grid_spacing=100e-9,
permittivity=1.0,
permeability=1.0,
courant_number=None, # calculate the courant number
)
return grid
E = np.exp(1j * (w_0 * t + M * np.sin(w_m * t)))
# E = np.exp(1j*(w_0*t))
# plt.plot(t, np.abs(E)**2)
plt.figure(1)
plt.plot(t, E.real)
plt.figure(2)
plt.plot(np.fft.fft(E.real))
#%%
import fdtd
grid = fdtd.Grid(
shape=(25e-6, 15e-6, 1), # 25um x 15um x 1 (grid_spacing) --> 2D FDTD
)
print(grid)
grid[11:32, 30:84, 0] = fdtd.Object(permittivity=1.7**2, name="object")
grid[13e-6:18e-6, 5e-6:8e-6, 0] = fdtd.Object(permittivity=1.5**2)
grid[7.5e-6:8.0e-6, 11.8e-6:13.0e-6,
0] = fdtd.LineSource(period=1550e-9 / (3e8), name="source")
grid[12e-6, :, 0] = fdtd.LineDetector(name="detector")
# x boundaries
grid[0:10, :, :] = fdtd.PML(name="pml_xlow")
grid[-10:, :, :] = fdtd.PML(name="pml_xhigh")
def create_patch_antenna(normalized_probe_position):
# [Samaras 2004]
# Probe fed microstrip antenna
# probe in middle and translated along X
# designed f = 2.3 GHz,
# excited with gaussian pulse
# centered at 2.3 GHz, harmonics up to 4 GHz
# 6-layer thick PML
# A non-uniform grid was used in the Samaras' model.
# The maximum cell size was 2 mm.
# other tests should be physically smaller if possible;
# performance limitation here seems to be
# the discretization size, not the timestep
border_cells = 6
patch_width = 59.4e-3 # m
patch_length = 40.4e-3 # m
substrate_thickness = 1.27e-3 # m
dielectric_constant = 2.42 # m
loss_tangent = 0.0019 #
N_substrate_cells = 3
spacing = substrate_thickness / N_substrate_cells
# 1 / (((1.27e-3 / 10) meters) / c) ≈ 100x f, A-ok
Nx = int(patch_width/spacing)+(2*border_cells)
Ny = int(patch_length/spacing)+(2*border_cells)
Nz = int(substrate_thickness/spacing)+(2*border_cells) + 2 # finite thickness of copper planes
grid = fdtd.Grid(
shape=(Nx, Ny, Nz),
grid_spacing=spacing,
permittivity=1.0,
permeability=1.0,
courant_number=None, # calculate the courant number
)
pulse_fwhm = 2.3e-9
simulation_steps = int(5 * (pulse_fwhm / grid.time_step))
pulse_center_time = (simulation_steps * grid.time_step) / 5.0
DomainBorderPML(grid, border_cells=border_cells)
sl = slice(border_cells, -border_cells)
copper_object = AbsorbingObject(permittivity=1.0, conductivity=1e8)
grid[sl, sl, border_cells:border_cells+1] = copper_object # ground plane
bottom_copper_plane = border_cells
top_copper_plane = (border_cells+1+N_substrate_cells)
grid[sl, sl, top_copper_plane:top_copper_plane+1] = copper_object #top plane
probe_Nx = int(patch_width/spacing)//2 + border_cells
probe_Ny = int(normalized_probe_position*(int(patch_length/spacing)//2)) + border_cells
times = np.arange(0,simulation_steps) * grid.time_step
waveform_array = normalized_gaussian_pulse(times, pulse_fwhm, center=pulse_center_time)
source = SoftArbitraryPointSource(waveform_array=waveform_array, impedance=50.0)
grid[probe_Nx,probe_Ny,border_cells+1] = source
grid[probe_Nx:probe_Nx+1, probe_Ny:probe_Ny+1,
border_cells+2:top_copper_plane+1] = copper_object # probe feed via
substrate = Object(permittivity=dielectric_constant)
grid[border_cells:probe_Nx, sl, bottom_copper_plane+1:top_copper_plane] = substrate
grid[probe_Nx+1:-border_cells, sl, bottom_copper_plane+1:top_copper_plane] = substrate
grid[sl, border_cells:probe_Ny, bottom_copper_plane+1:top_copper_plane] = substrate
grid[sl, probe_Ny+1:-border_cells, bottom_copper_plane+1:top_copper_plane] = substrate
# don't overlap with the source port!
return grid, source, simulation_steps
## Set Backend
fdtd.set_backend("numpy")
## Constants
WAVELENGTH = 1550e-9
SPEED_LIGHT: float = 299_792_458.0 # [m/s] speed of light
## Simulation
# create FDTD Grid
grid = fdtd.Grid(
(2.5e-5, 1.5e-5, 1),
grid_spacing=0.1 * WAVELENGTH,
permittivity=1.0,
permeability=1.0,
)
# sources
grid[50:55, 70:75, 0] = fdtd.LineSource(
period=WAVELENGTH / SPEED_LIGHT, name="linesource"
)
grid[100, 60, 0] = fdtd.PointSource(
period=WAVELENGTH / SPEED_LIGHT, name="pointsource",
)
# detectors
grid[12e-6, :, 0] = fdtd.LineDetector(name="detector")
# x boundaries
def test_default_courant_number_3d():
grid = fdtd.Grid(shape=(3, 3, 3))
assert grid.courant_number == pytest.approx((1.0 / 3.0) ** 0.5, rel=0.02)
def test_default_courant_number_1d():
grid = fdtd.Grid(shape=(3, 1, 1))
assert grid.courant_number == pytest.approx(1.0, rel=0.02)
def test_grid_shape_mix_of_floats_and_ints():
grid = fdtd.Grid(shape=(10.0e-9, 10.0e-9, 3), grid_spacing=5.0e-9)
assert (grid.Nx, grid.Ny, grid.Nz) == (2, 2, 3)
def test_grid_shape_of_ints():
grid = fdtd.Grid(shape=(3, 3, 3))
assert (grid.Nx, grid.Ny, grid.Nz) == (3, 3, 3)
fdtd.set_backend("numpy")
## Constants
WAVELENGTH = 1550e-9
SPEED_LIGHT: float = 299_792_458.0 # [m/s] speed of light
## Grid setup
# create FDTD Grid
grid = fdtd.Grid(
(1.5e-5, 1.5e-5, 1), # 2D grid
grid_spacing=0.1 * WAVELENGTH,
permittivity=2.5, # same as object
)
# sources
grid[15, :] = fdtd.LineSource(period=WAVELENGTH / SPEED_LIGHT, name="source")
# detectors
grid[-15, :, 0] = fdtd.LineDetector(name="detector")
# x boundaries
# grid[0, :, :] = fdtd.PeriodicBoundary(name="xbounds")
grid[0:10, :, :] = fdtd.PML(name="pml_xlow")
grid[-10:, :, :] = fdtd.PML(name="pml_xhigh")
# y boundaries