An ultra wideband coplanar waveguide (CPW) fed slot antenna is presented. A rectangular slot antenna is excited by a 50-CPW with an arc-shaped tuning stub. For the proposed antenna, the -10 dB return loss bandwidth could reach 15.6 GHz (3.7-19.3 GHz), which is about 135% with respect to the centre frequency of 11.5 GHz. Details of the antenna design, simulation and measured results on the return loss and the E-and H-plane radiation patterns of the proposed antenna are presented.
