This paper presents the enhancements obtained in the performance of the Sample Matrix Inversion (SMI) beamformer by the application of Reduced One Dimensional Mapped Real Transform (R-ID-MRT) algorithm. In SMI beamformers, computational complexity and the time required for computation is reduced when data is transformed with R-ID-MRT algorithm. The beam patterns, convergence to the desired beam output, minimization of mean square error in AWGN, Rayleigh and Rician channels of the R-ID-MRT SMI beamformers are comparable to that of conventional SMI beamformers.