To prevent the radio propagation disturbance of an antenna by adopting a bird injury preventing measure.

This antenna is composed of a cover 2 covering the top of a post 1 of an antenna monitoring a radio frequency wave radiated from an antenna of a localizer device, a pole 3 vertically attached to the upper face of the cover 2 and having a conical tip end, a pair of radiation parts 4, 5 attached to the top of the post 1, covers 6, 7 covering the end parts of the radiation parts 4, 5, plural poles 8, 9 attached to the covers 6, 7 and plural wires 10 connecting the top of the pole 3 to the poles 8, 9.