A coplanar wave guide (CPW)-fed ultra-wideband antenna with fork-like radiation patch is presented. The antenna consists of CPW ground with a wide slot, the fork-like radiation patch and the 50 Ω CPW fed structure. In this design, by adjusting the dimensions of the wide slot, a very wide impedance bandwidth has been produced. The detailed parameters of the proposed antenna are investigated by using HFSS. Experimental and numerical result shows that the proposed antenna, with compact size of 21× 28mm2, has an impedance bandwidth range from 2.7GHz to 10.9GHz for voltage standing-wave ratio less than 2, which can well meet the ultra wideband system applications.