Geometry

metasurface_py.geometry

Lattice and aperture geometry definitions.

CircularAperture dataclass

Cell-centered polar sampling grid over a circular aperture.

Parameters:

Name	Type	Description	Default
radius	float	Aperture radius [m].	required
n_rho	int	Number of radial samples.	256
n_phi	int	Number of azimuthal samples.	128

area property

Total aperture area [m^2].

cell_areas cached property

Exact annular-sector cell areas, shape (n_rho, n_phi) [m^2].

Uses 0.5(rho_out^2 - rho_in^2)d_phi so the cell areas sum exactly to pi*radius^2.

phi cached property

Azimuthal sample points (cell centers), shape (n_phi,) [rad].

positions cached property

Cartesian sample positions in the z=0 plane, shape (n_rho*n_phi, 3) [m].

Flattened with rho as the slow axis (matches cell_areas.ravel()).

rho cached property

Radial sample points (cell centers), shape (n_rho,) [m].

HexagonalLattice dataclass

Hexagonal (triangular) grid of elements in the xy-plane.

Rows are offset by half the x-spacing on alternating y-indices, creating a close-packed hexagonal arrangement.

Parameters:

Name	Type	Description	Default
nx	int	Number of elements per row.	required
ny	int	Number of rows.	required
dx	float	Element spacing along x [meters].	required
origin	NDArray[floating[Any]]	Center of the array, shape (3,). Defaults to (0, 0, 0).	(lambda: zeros(3, dtype=float64))()
element_mask	NDArray[bool_] | None	Boolean mask (nx, ny), True = active. None = all active.	None

dy property

Row spacing for hexagonal packing: dx * sqrt(3)/2.

mask property

Boolean mask of active elements.

num_elements property

Number of active elements.

positions property

Element positions, shape (N, 3) in meters, centered on origin.

RectangularLattice dataclass

Rectangular grid of elements in the xy-plane.

Parameters:

Name	Type	Description	Default
nx	int	Number of elements along x.	required
ny	int	Number of elements along y.	required
dx	float	Element spacing along x [meters].	required
dy	float	Element spacing along y [meters].	required
origin	NDArray[floating[Any]]	Center of the array, shape (3,). Defaults to (0, 0, 0).	(lambda: zeros(3, dtype=float64))()
element_mask	NDArray[bool_] | None	Boolean mask (nx, ny), True = active. None = all active.	None

area property

Physical area of the array [m^2].

extent property

Physical extent (width_x, width_y) of the array [meters].

mask property

Boolean mask of active elements.

num_elements property

Number of active elements.

positions property

Element positions, shape (N, 3) in meters, centered on origin.

from_wavelength(nx, ny, spacing_fraction, freq, origin=None) classmethod

Create lattice with spacing as a fraction of wavelength.

Parameters:

Name	Type	Description	Default
nx	int	Number of elements along x.	required
ny	int	Number of elements along y.	required
spacing_fraction	float	Element spacing as fraction of wavelength (e.g., 0.5).	required
freq	float	Reference frequency [Hz].	required
origin	NDArray[floating[Any]] | None	Center of array. Defaults to (0, 0, 0).	None