a interface with fixed backscatter 4*pi and that is perfectly isotropic

smrt/interface/radar_calibration_sphere.py

@@ -0,0 +1,40 @@
+# coding: utf-8
+
+"""Surface with a backscatter of 4pi.
+
+"""
+
+import numpy as np
+
+# local import
+from smrt.core.interface import Interface
+from smrt.core.lib import smrt_matrix, len_atleast_1d
+
+class RadarCalibrationSphere(Interface):
+
+    args = []
+    optional_args = {}
+
+    def specular_reflection_matrix(self, frequency, eps_1, eps_2, mu1, npol):
+
+        return smrt_matrix(0)
+
+    def diffuse_reflection_matrix(self, frequency, eps_1, eps_2, mu_s, mu_i, dphi, npol):
+
+        m = smrt_matrix.zeros((npol, len_atleast_1d(dphi), len_atleast_1d(mu_i)))
+        m[0:2, :, :] = 1.
+
+        return m
+
+    def ft_even_diffuse_reflection_matrix(self, frequency, eps_1, eps_2, mu_s, mu_i, m_max, npol):
+
+        m = smrt_matrix.zeros((npol, m_max + 1, len_atleast_1d(mu_s)))
+
+        # only mode 0, pola 0 and 1, are non-null
+        m[0:2, 0, :] = 1.
+
+        return m
+
+    def coherent_transmission_matrix(self, frequency, eps_1, eps_2, mu1, npol):
+
+        return smrt_matrix(0)

smrt/substrate/radar_calibration_sphere.py

@@ -0,0 +1,18 @@
+# coding: utf-8
+
+
+"""
+Implement the radar_calibration_sphere interface boundary for the bottom layer (substrate).
+
+"""
+
+# local import
+from smrt.interface.radar_calibration_sphere import RadarCalibrationSphere as iRadarCalibrationSphere
+from smrt.core.interface import substrate_from_interface
+
+# autogenerate from interface.radar_calibration_sphere
+@substrate_from_interface(iRadarCalibrationSphere)
+class RadarCalibrationSphere:
+    pass
+
+