diff --git a/src/gray_core.f90 b/src/gray_core.f90
index 13a89ce..ebeb3ff 100644
--- a/src/gray_core.f90
+++ b/src/gray_core.f90
@@ -164,6 +164,7 @@ contains
     ! Set original polarisation
     psipv(0) = params%antenna%psi
     chipv(0) = params%antenna%chi
+    call ellipse_to_field(psipv(0), chipv(0), ext, eyt)
 
     ! Error value for the whole simulation
     error = 0