A Study On Target Parameters Estimation Method Of Frequency Diverse Array MIMO Radar

In recent years,frequency diversity array(FDA)radar has attracted wide attention and research from domestic and foreign scholars because of its flexibility.Frequency diversity array is an equidistant linear array.The difference from an ordinary array is that frequency diversity array introduces a frequency offset far smaller than the carrier frequency between the array elements,thereby generating a distance-angle dependent waveform.Compared to conventional phased array radars,the freedom of distance dimension is added at the transmitter.Frequency diversity array radar virtualizes the degree of freedom of the transmitter to the receiver by using multiple-input multiple-output(MIMO)scheme,thus forming a virtual receive-transmit steering vector,which provides conditions for the joint estimation of the distance and angle of the target.Although frequency diversity array radars have been widely used to form distance-angle dependent waveforms,it is quite difficult to directly obtain the position information of a target through a conventional frequency diversity array radar.Due to the strong coupling of distances and angles,the problem of target distance ambiguity has been caused.In this thesis,a series of work is carried out based on frequency diversity array radar:1.The analysis on FDA beam pattern of the periodic and distance-angle coupling characteristics.On this basis,two kinds of receiving signal processing mechanism are introduced: the first one is the single frequency receiving processing,the receiving antenna receives only the same frequency signal which itself transmits;the second is all frequency signal receiving processing,the receiving antenna receive the signal which the transmitting antenna transmits.At the same time,this thesis analyses the formation conditions of the distance-angle coupling of frequency diversity array beam pattern in detail,and the distance-angle decoupling method is introduced,which is to design non-linear frequency offset.The target parameter estimation methods based on beam scanning and pulse compression for the traditional frequency diversity array MIMO(FDA-MIMO)radar with the second receiving mechanism are studied,and the problem of distance ambiguity is proposed.2.The target space location methods based on non-linear frequency offset FDA-MIMO radar are studied.Based on FDA-MIMO radar with nonlinear frequency offset,the thesis studies the traditional MUSIC method,reducing dimension MUSIC method and double-pulse MUSIC method in order to form a unique peak and achieve the super-resolution of multiple targets in the two-dimensional observation region of the distance-angle.At the same time,when the inference is at any peak of the beam,it is regarded as the target,which causes the loss of signal-to-noise ratio.The experimental simulation results verify the conclusion of this thesis.