Multiple Input Multiple Output (MIMO) radar [1-4] has been a hot topic in recent years. A MIMO radar system consists of multiple transmit antennas and multiple receive antennas, can capitalize on waveform diversity to significantly improve the radar’s performance. And the energy covers the entire surveillance space or a certain sector.Multiple carrier frequency waveforms have the advantages of easily generated and separated, satisfying the requirement of orthogonality, and thus can be applied to the MIMO radar, which have attracted much attention from researchers. However, MIMO radar has its own weakness in energy lose without beamforming.Many of the approaches exemplified by MIMO radar have been long employed without the "MIMO" nomenclature being used. The Synthetic Impulse and Aperture Radar (SIAR) [6-11] introduced in this paper is one of them. In fact, MIMO radar is inspired mainly by the SIAR [4]. And the basic concepts of SIAR can be summarized as follows: (1) By encoding the signals of each omnidirectional radiation element, the isotropic radiation of the entire surveillance volume is ensured with a large antenna array; that is, the beam pattern of the transmit signal is not formed in the spatial domain. (2) Signal components corresponding to each transmitting element are separated in the receiving system based on their codes. The time delay is calibrated at the received array, and then the signal components are coherently combined again to generate narrow pulses of target echoes, namely the equivalent transmitting beams. These features are the same as that of MIMO radar with collocated antennas [2], and thus SIAR is generally treated as a coherent MIMO radar system.In this paper, the history, advantages and disadvantages of SIAR will be introduced first. Next its applications on two