Novel arc-shaped antipodal slot antenna fed by microstrip line with an elliptical tuning patch for ultra-wideband (UWB) applications is proposed. Arc-shaped half-folded antipodal structure is employed to improve the radiation characteristics of the antenna. The antenna has been investigated numerically and experimentally and compared with conventional rectangular wide slot antenna. As is reported, the operation bandwidth of the antenna is from 2.7 GHz to more than 12 GHz, Stable omnidirectional radiation pattern with good polarization purity and flat gain performances can be achieved. It may be useful for Ultra-wideband polarization diversity applications.