Roles of matching layers for a shaped beam lens horn antenna

A radio collision avoidance system that is used at a crossing is now developing in the intelligent transport systems (ITS). For transponder antennas of this system, a lens horn antenna that can achieve a cosecant squared beam in a vertical plane and a wide beam in a horizontal plane was developed. There, necessity of matching layers was pointed out. In this paper, roles of matching layers are shown through numerical and experimental results. Electrical field disturbance in the horn is cleared by using FDTD analysis. Realization of shaped beam characteristics is shown through numerical and experimental result.