differt.em.BackscatteringPattern

class BackscatteringPattern(alpha_r=1.0, alpha_i=1.0, lambda_=0.5)

Bases: AbstractScatteringPattern

A diffuse scattering pattern combining a forward and a backscattering lobe.

Following Degli-Esposti’s combined scattering model [7] (as also used by Sionna RT’s BackscatteringPattern), this mixes two directive lobes \(F_\alpha\) (see DirectivePattern for the lobe formula and its normalization caveat): one centered on the specular direction \(\hat{k}_{sp}\) (like DirectivePattern, with width alpha_r), and one centered on the retroreflection direction \(-\hat{k}_i\) (back toward the transmitter, with width alpha_i), combined as

\[f_s(\hat{k}_i, \hat{k}_s, \hat{n}) = \Lambda F_{\alpha_R}(\hat{k}_s, \hat{k}_{sp}) + (1 - \Lambda) F_{\alpha_I}(\hat{k}_s, -\hat{k}_i),\]

where \(\Lambda \in [0, 1]\) (lambda_) is the forward lobe’s weight; \(\Lambda = 1\) reduces to DirectivePattern, while \(\Lambda = 0\) gives a purely retroreflective (backscattering) lobe, e.g., as observed on rough surfaces exhibiting a strong return toward the transmitter (e.g., vegetation, some building facades).

Attributes

alpha_i	The backward-lobe width parameter \(\alpha_I \geq 1\).
alpha_r	The forward-lobe width parameter \(\alpha_R \geq 1\).
lambda_	The forward-lobe weight \(\Lambda \in [0, 1]\).

Methods

Detailed documentation

alpha_i: Float[ArrayLike, ""] = 1.0

The backward-lobe width parameter \(\alpha_I \geq 1\).

alpha_r: Float[ArrayLike, ""] = 1.0

The forward-lobe width parameter \(\alpha_R \geq 1\).

lambda_: Float[ArrayLike, ""] = 0.5

The forward-lobe weight \(\Lambda \in [0, 1]\).