An improved Ultra-Wide Band (UWB) and high gain rectangular antenna is specifically designed in this paper using planar-patterned metamaterial concepts. The antenna has isolated triangle gaps and crossed gaps etched on the metal patch and ground plane, respectively. By changing the pattern on the ground, the impedance matching characteristics of the antenna are much better. The -10dB impedance bandwidth of the proposed antenna is 3.85-15.62GHz, which is about 267% broader. The proposed antenna has an average gain of 5.42dB and the peak is 8.36dB at 13.5GHz.