Research On The Detection Method Of Rotational Doppler Based On Vortex Electromagnetic Wave

Vortex Electromagnetic(EM)wave carrying the Orbital Angular Momentum(OAM)is a special EM wave whose phase wave-front is different from the traditional plane wave,and its unique spiral phase distribution has a unique advantage in the detection of the spinning targets.Based on the Rotational Doppler effect of vortex EM waves,this thesis studies the Rotational Doppler detection method,including: Rotational Doppler formation mechanism,Doppler resolution of vortex EM waves,the estimation of spinning target motion parameters,the Rotation Doppler analysis of nonideal motion target,etc.The work of this thesis provides theoretical basis for related applications such as vortex EM wave-based spinning target detection methods.In the introduction,the generation method of vortex EM wave is introduced,and its research status at home and abroad has been summarized.Secondly,the Rotational Doppler detection method of vortex EM wave is summarized,and the background and significance of rotational target detection is introduced;the structure of this paper is described.In Chapter 2,the mainly part is focused on the formation mechanism of the Rotational Doppler effect and its Rotational Doppler resolution.From the basic expression of EM field,the relationship between the equal phase plane of the linear momentum and angular momentum is pointed out.The theoretical expression of the Rotational Doppler effect is derived from the Laguerre-Gaussian(LG)model,and the meaning of the each component is pointed out.Based on the fuzzy function theory,the fuzzy function of the vortex EM wave is derived.The Rotation Doppler resolution under the single pulse and multi-pulse system is given.It is pointed out that the resolution of the angular velocity of the spinning target is inversely proportional to the topological charge and pulse width.In Chapter 3,the motion parameters of the spinning target are estimated,and the uniformly accelerated target is used as the main detection object.The detection methods of WVD distribution,FRFT algorithm and LVD algorithm is used as the main estimation algorithm.The acceleration and the original value are estimated,and the source of each algorithm error and the applicable scenarios are analyzed.In Chapter 4,the Rotational Doppler of nonideal motion targets is analyzed.The echo equations of the targets is derived and based on that,the Doppler under the lateral linear motion,the inclined circular motion and the off-axis circular motion of the point target are analyzed.The regular of the Doppler analysis for the OAM wave-based target detection is given.In the last part of the thesis,the research work is summarized and directions of the future work are provided.