Local form of the radiation condition: application to curved dielectric structures

The form taken by the radiation condition in the local co-ordinate system relevant to a curved radiating structure is not the same as it is at very great distances. It may contain a term that appears as if it were an incoming or growing wave. A detailed analysis has been made of the appropriate form of the condition in the cylindrical and toroidal systems, and has been applied to radiation form curved dielectric slabs and fibres.