A novel compact ultra‐wide band antenna with L‐shaped slot is presented. The printed antenna is fed by a microstrip feed line to achieve impedance matching for the SMA connector. The proposed antenna offers 118% bandwidth when printed on a substrate of dielectric constant 4.4 and has an overall dimension of 23.7 × 23.7 × 0.8 mm3. The simulated and measured reflection characteristics of the antenna with the variation of key‐parameters along with radiation patterns of the final antenna are presented and discussed. In addition, by decreasing the dimension of radiating patch, band‐notched properties in the lower wireless local area network (WLAN) (5.15–5.35 GHz) or higher WLAN (5.725–5.825 GHz) bands are achieved. With the compact size and broadband, this antenna is very suitable for using in a trade‐off which has to be taken account for a design of miniaturisation.