Research On Topology Of Circular Lattice Array In Aperture Synthesis Radiometer

Aperture synthesis radiometer(ASR)use small aperture antennas,which equivalent to large one,to achieve radiation signal imaging with high spatial resolution.Antenna array is an important part of ASR.Topology of array determines the sampling distribution of spatial frequency domain and the quality of image.The study on topology of array is a key subject of ASR.In this dissertation,array configurations in constraint annular section are studied.The main contents are as follows:A constraint relaxation method is proposed to design circular lattice array(CLA)because of original CLA's constructive disadvantages that not all non-hole CLA configurations exist.The affection of relative position is analyzed by varying circle center's position.This letter relaxes circle center's constraint and also proposed a fitness function used to optimize its position with simulated annealing.A filled CLA configuration is obtained through the optimized circle center.Simulated annealing and particle swarm optimization are proposed to optimized element positions chosen from filled CLA without holes.The comparison of two methods' performance is carried out.CLA using constraint relaxation could feed previous drawback.Corresponding array configurations also have less element numbers,which can save hardware costs.Sensitivity is an important performance parameter of ASR.In this paper,CLA based on optimum sensitivity is proposed.Firstly,general CLA(GCLA)is defined.The application requirement could satisfy by adjusting radii of two circles,minimum interval of elements and element numbers flexibly.Then,the relationship between degradation factor(DF)and radiometric sensitivity is analyzed.Taking DF as function,two methods are applied to find optimum sensitivity: greedy constructive algorithm and simulated annealing stochastic approach.Numerical results of two methods are carried out.Finally,simulated results verified effectiveness of this method,i.e.achieving optimum sensitivity of GCLA by minimizing DF.