differt.em.diffraction_coefficients

diffraction_coefficients(wavenumber, n, phi_i, phi_d, L_i, L_r_n=None, L_r_o=None, sin_beta_0=None, n_r_o=None, n_r_n=None, d_o=None, d_n=None)

Compute the diffraction coefficients based on the Uniform Theory of Diffraction.

The implementation closely follows what is described in [11, p. 268-273].

Unlike fresnel_coefficients, diffraction coefficients depend on the radii of curvature of the incident wave and the wedge geometry.

Parameters:

• wavenumber (Float[ArrayLike, "*batch"]) – The wavenumber \(k\).

• n (Float[ArrayLike, "*batch"]) – The wedge parameter \(n\) (exterior wedge angle is \(n \pi\)).

• phi_i (Float[ArrayLike, "*batch"]) – The incident angle \(\phi_i\) (or \(\phi'\)) in radians, measured from the o-face.

• phi_d (Float[ArrayLike, "*batch"]) – The diffracted angle \(\phi_d\) (or \(\phi\)) in radians, measured from the o-face.

• L_i (Float[ArrayLike, "*batch"]) – The distance parameter associated with the incident shadow boundary.

• L_r_n (Float[ArrayLike, "*batch"] | None) – The distance parameter associated with the reflection shadow boundary for the n-face. Defaults to L_i.

• L_r_o (Float[ArrayLike, "*batch"] | None) – The distance parameter associated with the reflection shadow boundary for the o-face. Defaults to L_i.

• sin_beta_0 (Float[ArrayLike, "*batch"] | None) – The sine of the angle of incidence on the edge, \(\sin \beta_0\). Defaults to 1.0 (broadside incidence).

• n_r_o (Complex[ArrayLike, "*batch"] | None) – The relative refractive index of the o-face material. If None, the o-face is assumed to be a Perfect Electric Conductor (PEC).

• n_r_n (Complex[ArrayLike, "*batch"] | None) – The relative refractive index of the n-face material. If None, the n-face is assumed to be a Perfect Electric Conductor (PEC).

• d_o (Float[ArrayLike, "*batch"] | None) –

  The thickness of the o-face material.

  If None (default), or if (element-wise) negative – the same “no thickness specified” sentinel used elsewhere, e.g. compute_received_fields – the o-face is treated as an infinite half-space, i.e., using reflection_coefficients. Otherwise, the finite-thickness slab formula (slab_coefficients) is used, matching Sionna RT’s dielectric-wedge diffraction model. Unused if n_r_o is None (PEC).

• d_n (Float[ArrayLike, "*batch"] | None) – The thickness of the n-face material. See d_o.

Return type:

tuple[Complex[Array, "*batch"], Complex[Array, "*batch"]]

Returns:

A tuple containing the soft and hard diffraction coefficients \((D_s, D_h)\).