In this article, an exponential tapered Vivaldi antenna is designed. A ZIM (Zero Index Metamaterial) is introduced into the antenna to enhance its gain in whole of the ultrawideband. The proposed structure is covering the ultrawideband of 3.1-10.6 GHz as specified by FCC. The antenna has a bandwidth of 8.2GHz for the range 2.93- 11.13GHz. After introduction of metamaterial in the antenna, the gain of the antenna is enhanced in whole of the ultrawideband whereas maximum enhancement in the gain is 2.22dB at 10.6GHz. The proposed antenna also has low cross polarization less than -30dB for all the frequencies.