The present invention is related to a mobile communication device. The device comprises a dielectric substrate, a first ground plane, an antenna element, a second ground plane, and an equivalent band-stop circuit. The first ground plane is disposed on the dielectric substrate. The antenna element is disposed on the dielectric substrate or nearby the dielectric substrate and is connected to a signal source disposed on the dielectric substrate. The second ground plane is disposed nearby one edge of the first ground plane and is connected to the first ground plane through a metal strip. The equivalent band-stop circuit is disposed on the second ground plane and includes a slit and a capacitive element. The open end of the slit is near the metal strip. The capacitive element is mounted across the slit.