High-resolution Frequency Diversity Array Pattern Synthesis Technology Research

Frequency diverse array is different from phase array which depends on the phase shifter,it adds frequency offsets far less than carrier frequency in the transmitting signals to make the beampattern of the system related to the range and angle,realizing the automatic scan in the airspace.Thus,frequency diverse array radar greatly simplifies the systems' structure,reduces the cost,power consumption and the complexity of the array.This thesis takes the beampattern of frequency diverse array as the main research object,proposing a new method to synthesis a high-resolution,timeinvariant and dot-shaped beampattern.It solves coupling,periodicity,time-variant and low-resolution defects of the standard Frequency Diverse Array radar.The beampattern of the standard frequency diverse array is coupled with the range and angle,and the beampattern is S-shaped,however,non-linear frequency offsets can damage the grating lobe,effectively decoupling and suppressing the periodicity of range.This thesis proposes that genetic algorithm optimizes the time-dependent frequency offsets to achieve the time-variant and dot-shaped beampattern.The beampattern of the standard frequency diverse array is low-resolution,which is not favorable for the energy concentration.New transmitting signals based on conjugatesymmetry is proposed in this thesis.Conjugate-symmetrical signals are cosine real signals in essence,which satisfies the condition that can only generate real signals in practical.Since the optimization algorithm cannot achieve real-time processing,this thesis proposes that using two-dimensional chaotic sequence modulated timedependent frequency offsets to effectively decouple and suppress the periodicity and sidelobe,synthesizing the high-resolution,time-invariant and dot-shaped beampattern.Much simulation results verify the correction and effectiveness of the proposed method.