Mimo Radar Performance With Beamforming Technology

The researches for the performance and the related beam forming technologies of transmit diversity MIMO radar are the main content of this article.The improvement of anti-intercept performance is one of the important advantages of MIMO radar. Phased array radar transmits narrow high-gain beam, so the space power densities in the beam direction is high. For this reason, phased array radar is easy to be intercepted by enemy's electronic reconnaissance. By contrast, MIMO radar transmits wide low-gain beam which makes L times reduce of space power densities, where L means the number of transmitting channel, and the anti-intercept performance is improved for that. Based on the analysis of space power densities of MIMO radar, we come to the conclusion that the intercepted distances of MMO radar is L^1/2 times less to phase array radar under the condition of the same transmit elements and power.The reduction of requirement for dynamic range is another important advantage of MIMO radar. Based on the analysis of the requirement for dynamic range of different radar working mode, we get the conclusion that the requirement for dynamic rang of MIMO radar can be N²L² times less than traditional analog beam forming phased array radar at most, where N means the number of receive elements and L means the number of transmitting channel. The MTD and CFAR detect performance of MIMO radar and phased array radar under the condition of certain receiving clipping level is analyzed with simulation for three types of signals which are LFM signals, phase encoding signals and frequency encoding signals. MIMO radar's strength of weak target detection under strong clutter is proved by the simulation results. Random initial phase method is introduced to solve the problem of periodic peak in echo signals of OFDM-LFM signal MIMO radar.For the reason of transmitting orthogonally coded waveforms, the structure of receiving beam forming of MIMO radar is different from phased array radar. The main difference is that a set of matched filters are needed for MIMO radar to abstract the echo waves caused by each orthogonally signals and to form equivalent transmit beam at the receiving end. Two kinds of beam forming structure are compared and analyzed in detail and the advantages and disadvantages of each structure are pointed out.Multiple-beam amplitude-comparison angular estimation method is analyzed in this article and the method of determining the number and directions of multiple beams of MIMO radar is introduced. The simulation results of angular estimation are offered and the estimation residual is also analyzed.At the end of this article, the simulation platform of MIMO radar system and the simulation interface are introduced. The problems faced in the process of platform building and the related solutions are analyzed briefly.