"FIGS. 11A to 11C are an external perspective view and exploded perspective views showing the structure of parts of the waveguide horn antenna array of the present embodiment, FIG. 11A is an external perspective view of the waveguide horn antenna array, FIG. 11B is an external perspective view of an upper conductor plate 10 a, and FIG. 11C is an external perspective view of a lower conductor plate" . . . .