Broadband antennas mounted on vehicle

An antenna assembly comprises: a dielectric substrate; a first ground region disposed on one side of a feed line disposed on the dielectric substrate; a radiator region in which a first side and a second side corresponding to the opposite side of the first side form end portions of conductive patterns such that the conductive patterns having different widths are formed in a plurality of step structures; and a second ground region disposed on the other side of the feed line, wherein the first ground region may be formed to have a length greater than or equal to that of the second ground region in one axial direction. The number of steps on the second side may be greater than or equal to the number of steps on the first side.