Abstract: A multiband antenna system installed onto a circuit board of a mobile device is provided. The antenna system includes a planar dielectric substrate, an upper conductor formed on an upper surface of the dielectric substrate and shaped as a coplanar wave guide and includes first and second ground parts and a radiator, and a lower conductor formed on the lower surface of the dielectric substrate and shaped as a coplanar wave guide and includes third and fourth ground parts and an electrode part, via-holes that pass through the dielectric substrate and are electrically connected to the first ground part to the third, the second ground part to the fourth, and the radiator to the electrode part, respectively, and solder balls connect the electrode part to an electric wire of the circuit board and also the third and fourth ground parts to the ground of the circuit board.