A wideband antenna includes a grounding terminal, a first radiator disposed on a first plane, a feeding terminal formed on the first radiator, where the feeding terminal is to transmit and receive radio signals via the first radiator, and a second radiator disposed on the first plane, electrically connected to the grounding terminal, and including a part parallel to a side of the first radiator, wherein a minimum gap between the second radiator and the first radiator allows the second radiator and the first radiator to generate a coupling effect therebetween, so as to exchange radio signals between the second radiator and the first radiator.