Research On Beam Pattern Synthesis And Long-time Integration For Monostatic Collocated Mimo Radar

MIMO radar is a new kind of radar system which attracted much attention in recent years. This paper firstly summarizes the present situation of MIMO radar, points out the current trends and opportunities of the development of MIMO radar. And then we introduced the classification and basic principle of MIMO radar in detail. Among them, this article mainly introduced the wide beam MIMO radar based on subarrays. The array receiving signal model is deduced, and then we presents a subarrays partition method. Because of its advantages of adapting large array and decoupling the beamforming and waveform design compared with other types of MIMO radar, this paper chose this type of MIMO radar as the research object.This paper mainly studied two key technologies of the wide beam MIMO radar based on subarrays. The first technology is wide beam pattern synthesis, this paper first presents a subarray emission signal model, and then puts forward a method called wide beam synthesis method based on adaptive gradient search. Among them, the phase-only weighted is chosen, analysis shows that this way of weighted can effectively use the energy of transmitter, which is the most suitable way for MIMO radar system. And the optimal method we choose is the adaptive gradient search method. It is an improved gradient method, which has fast convergence rate, and is not easy to fall into local optimal solutions, etc. The wide beam synthesis method we presents is based on the optimization idea, which is still not been widely adopted in the field of MIMO radar beamforming research, so we make up for the vacancy. And then we gives the simulation analysis of the method in detail, analyzed the effects of various parameters on beam design result. It is proved that the method we propose is good.In this paper, the second key technology of the MIMO radar is the long-time integration technology. Compared with the traditional radar system, MIMO radar usually requires longer integration time, which leads to seriously target echo envelope moving caused by the speed of target. If we want to get effective coherent integration result in a long term, the problem of envelope moving must to be solved. This paper firstly presents an orthogonal continuous phase code waveform as the research object, and then deduces the output model and then analyzes the causes of echo envelope moving. Then we choose the Keystone transform as the echo envelope correcting method. We introduced the principle of Keystone transform and how Keystone transform is implemented under the condition of digital signal processing(DSP). And at last we introduced the echo coherent integration method after Keystone transform. Finally, this paper gives the simulation results of correcting echo envelope moving by Keystone transform. Studies show that the Keystone transform is suitable for both single-target and multi-target situations. The final echo coherent integration simulation results are given in this paper too. The simulation proves that the method adopted in this paper can solve the problem of MIMO radar long-time integration very well.