A printed circuit board (PCB) is disposed to stand vertically on a main board and having a first surface and a second surface opposite to the first surface. A main antenna pattern is formed on the first surface of the PCB to operate in dual band including a low frequency band and a high frequency band. A bandwidth extension pattern is formed on the second surface of the PCB and formed to operate in the high frequency band, the bandwidth extension pattern having a coupling stub which forms an overlapping portion with a portion of the main antenna pattern, with the PCB interposed therebetween, to implement an antenna having an extended bandwidth, which operates together with the portion of the main antenna pattern in the high frequency band.