A novel ultra-wideband (UWB) planar monopole antenna is presented, which has the characteristic of a fixed band notch and a switchable and continuously tunable band notch. To achieve a dual-band notch, an E-shaped resonator is mounted beside the feeder. By loading a single varactor diode on the Eshaped resonator, the band-notch of the antenna has two modes. Mode 1 is selected when there is a single narrow-band interference. In this mode, the bias voltage is 0 V. One of the band notches will be off-state, and there is a single fixed band notch at the WiMAX band (3.3–3.8 GHz). Mode 2 is selected when there is an extra narrowband interference. In this case, A bias voltage greater than 0 V is given. Therefore, a fixed band notch and a continuously tunable band notch are obtained in this antenna. As the bias voltage increases, the tunable band-notch frequency changes continuously from 3.1 to 5.6 GHz.