A wideband antenna system includes a metal radiating portion, an aperture contact, a feed contact, an aperture tuner, an impedance tuner, a first switch, and a second switch. Two ends of the metal radiating portion respectively include a first contact and a second contact. The aperture contact is electrically connected to the metal radiating portion and is located between the first contact and the second contact. The feed contact is electrically connected to the metal radiating portion and is located between the first contact and the aperture contact. The aperture tuner is electrically connected to the aperture contact, and the impedance tuner is electrically connected to the feed contact. The first switch is electrically connected between the first contact and a zero-ohm resistor to selectively effect connection of the first contact to the zero-ohm resistor. The second switch is electrically connected between the first contact and the impedance.