Two element UWB diversity antenna with defected ground structure and parasitic elements with high gain is proposed. Total antenna size of designed two elements multiple input multiple output system is reduced by sharing radiator between two circular antenna elements. The shape of ground plane is optimised to achieve ultra wide band characteristics (2.43–12 GHz). With the utility of defected ground structure effective area of antenna is reduced as well as there is suppression of cross polar fields. Reduction in mutual coupling is studied by using parasitic element. Simulated and measured results shows that, ultra wide bandwidth can be achieved with good isolation (S12- 15 dB), maximum simulated gain of 6 dBi and maximum efficiency 83%. Correlation coefficient between two antennas elements is near to zero proves antenna is suitable for diversity performance. The compact size of antenna with dimensions 50 mm 9 40 mm exhibit nearly omnidirectional pattern in H plane.