Optimization Of Phase And Amplitude In Intergrated Photonics Based 2D Phased Array

Phased array radar has important application prospects in the field of electronic warfare be-cause of its flexible beam pointing,strong anti-interference ability and high reliability.The ampli-tude distribution of the antenna array affects the beam shape,and the phase distribution affects the beam direction.The phase distribution is realized by the phase shift unit.Traditional phased arrays use the phase shift unit based on the electrical processing methods,which can no longer meet the requirements in complex environments,including large bandwidth,large dynamic range and high frequency bands.Optical true time delay network can deal with it.Besides,it also has the advan-tages of low transmission loss and anti-electromagnetic interference.Compared with the optical true time delay network built by discrete devices,the true time delay network based on integrated photonics can reduce the system volume and the structural complexity.In this thesis,optimization of phase and amplitude in Intergrated Photonics Based 2D Phased Array is studied,which aims to improve the scanning beam performance of the system.Among the integrated optical true delay lines,the silicon-based binary waveguide delay line has the advantages of large bandwidth,large delay range,simple principle and stable performance.However,binary delay line is based on optical path switching,which will cause delay dispersion quantization errors.In addition,limited by the accuracy of fiber cutting,the length of the connection link in the system cannot be precisely controlled,which causes random errors.Therefore,the beam pointing angle error of the phased array based on the binary optical true delay network is relatively large.In order to improve the beam pointing accuracy,the influence of delay quantization error and fiber random error on the beam pointing angle is studied,and a new delay structure that com-bines discrete binary delay with continuous adjustable delay is analyzed,which eliminates discrete quantization error and reduces complexity compared with simple continuous adjustable delay line.Combined with the two-dimensional optical control network,the relationship between the phase error and the beam pointing angle error under this delay structure is analyzed and deduced,and a phase optimization algorithm based on linear programming is designed to adjust the continuous delay part of the delay structure,thus changing row delay and column delay.The simulation results show that this delay structure and phase optimization can overcome the quantization error problem of the existing binary delay line and optimize the random error of the link length.As a result,the beam pointing angle accuracy is improved.In the microwave photonic phased array,the amplitude distribution of the antenna array ele-ments will affect the side lobe level,and too high side lobe will affect the fidelity of the signal.In this thesis,the relationship between the antenna array element amplitude distribution and side lobes is analyzed.Based on the overall design of row and column amplification in a two-dimensional optical control network,an amplitude optimization algorithm based on quadratic programming is proposed to adjust the gain of row and column amplification.The overall windowing is performed on the amplitude distribution of each row and each column,which reduces the side lobes while reducing the complexity.The engineering realization of the amplitude optimization algorithm is introduced,and the feasibility of the algorithm in practical engineering application is preliminarily confirmed.Finally,the joint optimization of amplitude and phase is realized by simulation,which proves that the amplitude and phase optimization algorithm can simultaneously reduce the beam pointing error and reduce the side lobes.