In this paper, a novel microstrip fed compact multiple-input-multiple-output (MIMO) antenna is proposed for portable Ultra wideband (UWB) applications. The proposed antenna consists of two octagon shaped monopole antennas placed perpendicular to each other. Two protruding ground stubs are added and a short ground strip is used to connect the two ground planes of octagon shaped monopoles together. This forms a common ground plane to attain good isolation and impedance bandwidth. A prototype of the MIMO antenna with a dimension of 27 &Times; 40 mm2 is simulated and the antenna performance is studied in terms of reflection co-efficient at the two input ports, coupling between the two input ports, radiation pattern and realized peak gain. The performance of the antenna satisfies the impedance bandwidth of greater than 3.1 to 10.6 GHz, low mutual coupling of less than -15 dB across the frequency band. © 2015 IEEE.