fix(em): incorrect diffraction matrix in RadioMaterial (#68)

Author: jeertmans

src/sionna/rt/radio_materials/radio_material.py

@@ -1078,16 +1078,17 @@ def a_p_m(beta):
         w_n_out = jones_matrix_rotator(ko_local, e_r_s_n_hat, phi_hat)
 
         # Compute fresnel coefficients for both faces
+        wavelength = dr.two_pi / wavenumber
         r_te_0, r_tm_0, _, _ =\
             itu_coefficients_single_layer_slab(dr.abs(dr.sin(phi_prime)),
                                                eta,
                                                self._d,
-                                               wavenumber)
+                                               wavelength)
         r_te_n, r_tm_n, _, _ =\
             itu_coefficients_single_layer_slab(dr.abs(dr.sin(exterior_angle-phi)),
                                                eta,
                                                self._d,
-                                               wavenumber)
+                                               wavelength)
         #
         # Construct R_0 and R_n matrices
         #

test/unit/test_radio_maps.py

@@ -518,7 +518,7 @@ def test_diffraction_street_canyon():
                             diffraction=True,
                             diffraction_lit_region=True)
 
-    rx_indices = [(120, 120), (160, 50), (160, 150), (120, 200), (220, 100),
+    rx_indices = [(120, 120), (170, 50), (160, 60), (120, 200), (220, 100),
                   (175, 350)]
     for i, p in enumerate(rx_indices):
         rx_pos = rmap.cell_centers[p[0], p[1]]