In this study, we present a new code design criterion for space-time block codes. Using the proposed criterion, it is possible to determine linear dispersive space-time block codes that are able to work in high rates such as R = 8 or 16 bit/channel use. These new codes differ from previously proposed linear dispersed codes by the simplicity of the transmitter design, in that, every antenna transmits strictly from a QAM constellation. Furthermore, the criterion aims to maximize the channel capacity by the help of crucial equation of number of symbols = number of channel uses X min(number of transmit antennas,number of receive antennas) and to minimize the bit-error probability at the same time. The minimization of symbol-error probability is achieved by the minimization of bit-error probability. We also produced some simulation results for comparison of the performances of various linear dispersive codes to strengthen our claims.