A microstrip line feed modified Sierpinski square fractal antenna for ultra-wide band (UWB) with band notch characteristics is presented. UWB operation (3.1-10.6 GHz) is achieved by increasing the numbers of iteration and rectangular grooved ground plane. The band rejection characteristic is realised by a ∩-slot in the feed line. The proposed antenna has a volume 34 × 34 × 1.6 mm3 with a square shape structure and shows omnidirectional radiation patterns. The measurement results indicate that the antenna offers UWB operation and a notch at 5.5 GHz (5-6 GHz) for a reflection coefficient below -10 dB which covers the wireless local area network band. Acceptable agreement is obtained between the simulated and measured antenna performance parameters. These characteristics demonstrate that the proposed antenna is an attractive candidate for UWB applications. © The Institution of Engineering and Technology 2014.