In a resonant frequency tunable antenna, a body includes a dielectric substance and a magnetic substance. A first radiator is disposed on a first predetermined area of the body and has a feeding pin connected thereto. A second radiator is disposed on a second predetermined area of the body. Also, a switch is disposed on the body to be connected between the first and second radiators. In addition, a power supply pin is electrically connected to the switch and extends downward through the body.