A wide-band antenna and a manufacturing method thereof are provided. The wide-band antenna includes a substrate, a first radiator, a second radiator, a grounding portion, and a signal feeding portion. The first radiator is disposed on a first surface of the substrate while the second radiator is disposed on the first surface or a second surface opposite to the first surface. The first radiator and the second radiator are spaced apart by a predetermined distance. The grounding portion is disposed on the substrate to couple with the second radiator. The signal feeding portion has a coupling unit disposed on the second surface and at least partially overlapping the first radiator. The signal feeding portion is coupled with the grounding portion and feeds signals to excite the first radiator to form a first band mode through coupling effect by the coupling unit. The first radiator feeds signals to excite the second radiator to form a second band mode by coupling effect.