In this paper, the construction of space time block (STBC) over maximum rank distance (MRD) codes is presented for different configuration of transmit antennas. Different fields are used to construct such codes. To conserve the rank of the code, Gaussian integers have been used for modulation for 3-transmit antenna scenario to evaluate their performance. Furthermore, a comparative study with corresponding orthogonal code is also presented. First, It is shown through simulation that rank codes in any antenna configuration can achieve full diversity gain similar to what orthogonal codes can do in most cases. The simulation results show that orthogonal codes generally perform better than MRD for any given configuration. However, a special case is described in which rank code outperforms orthogonal code for 2 × 1 antenna configuration provided the two conditions are satisfied.