The aim of this work is to develop an algorithm of digital beam forming for coherent MIMO radar with frequency diversity. We discussed ways to simplify hardware implementation of MIMO radar using serial method of MIMO channel matrix forming. A model of probing waveform, which allows performing digital beam forming at functional level is proposed. The bearing resolution of MIMO radar is estimated based on radiation pattern and ambiguity function modeling. Serial manner of MIMO channel matrix forming requires a larger number of orthogonal probing waveforms and twice longer time, relative to the traditional parallel method.