The UWB dipole antenna with flat and sharp band notch characteristics is proposed to obtain both WLAN band notch and a compact UWB RF-front structure. To achieve all these characteristics, the antenna acts as a multi-resonance radiator. To suppress interference from WLAN system, the antenna is sharply mismatched at WLAN band. To guarantee the suppression in the band, the notch characteristics are flat at WLAN band. The fabricated antenna has the operating bandwidth of 2.7 GHz to 11.0 GHz for VSWR < 2. The rejected frequency range is measured as 5.10 GHz ∼ 5.75 GHz for -3 dB return loss. The radiated power at this band is measured as 15 dB less than the power at the operating frequency band. From the measured results, it is apparent that the proposed antenna provides compact RF-front in the UWB system without the additional circuit for the suppression of the WLAN band.