Abstract: An ultra-wideband fractal antenna is proposed, which has an isosceles trapezoid ground-plane. Increasing fractal iterations and optimizing ground-plane shape can achieve a better impedance matching so as to realize Ultra-WideBand (UWB) antenna performance. The presented fractal antenna offers a -10 dB return loss bandwidth in the range of 4.2 to 17.5 GHz (relative band is 122.6%) with electrical dimension of 0.350.35. Thus, this type of antenna is suitable for C, X, Ku and UWB band communications, which may have a wide application prospect. The measured results fit well with the simulation results, and the effectiveness is validated using the measured results.