Research On The Synthesis Method Of Point Pattern Based On Frequency Diversity Array

The beampattem synthesis technique can converge the radar transmit energy in the interested spatial domain.The related research about focussing has been developed from the angle dimension to the distance-angle two-dimensional space.This technology has wide application prospects in high-resolution imaging,long-range energy transmission,medical targeted therapy and other aspects.Frequency diversity array(FDA)is a new type of array without phase shifter.Its beampattem is controlled by the signal frequency offset between each array element and is related with distance,angle and time.FDA can achieve tihe objective of focusing the emitted energy on the target position.Therefore,based on the frequency diversity array,this thesis proposes a method of dot-shape beampattem synthesis and designs a transmit signal.Firstly,based on the research of pattern characteristics of the existing frequency diversity array,the method of FDA design based on exponential frequency offset with non-uniform array spacing is proposed.Then,the beampattem of each case is simulated by Matlab.The influences of frequency offset and array spacing on the pattern are analyzed,and the design parameters for initial synthesis of the dot--shape beampattem are given.Secondly,to solve tihe problem of low focusing resolution,the convex optimization theory is introduced to optimize the amplitude weight of the transmit signal,and the transmission power of a single array element is constrained.The method of transmit beampattem synthesis based on convex optimization theory is applied to frequency diversity array dot-shape pattern synthesis,focusing resolution is improved while ma:intaining low sidelobes.Finally,this thesis designs a transmit signal in the form of pulse and applies the Morlet vavelet to the design.The chaotic sequence is used to control the frequency offsets.This transmit signal can achieve the dot-shape beampatterm with higher focusing resolution than the previous algorithms.Simulation experiments prove the effectiveness of the design signal in this thesis.