A very compact and small sized 2-element planar Ultra Wide band (UWB) antenna having high isolation with band rejection characteristics designed on a FR4 substrate (23 × 26 × 0.8 mm ³ ) is presented in this paper. Each antenna element have a rectangular stepped-slot and a z-shaped slot, both etched in ground plane. The rectangular slot, proximity fed by a 50 Ω micro-strip transmission line, acts as a main radiator while z-shaped slot acts as a filter for rejecting the full WLAN band (5.15-5.85 GHz). Use of an inverted T-shaped slot near top end of ground plane improves isolation more than 24.5 dB in lower UWB band i.e. 3-5 GHz, while the rectangular vertical slot etched at center of the ground plane near the bottom edge reduces the mutual coupling at lower as well as at higher UWB band i.e. 5 - 10.6 GHz. Both measured and simulated results are presented which are found generally in good agreement.