Research On Direction Finding Technology Of Elliptical Array Interferometer

Interferometer direction-finding system is widely used in passive detection system because of its high accuracy and simple structure.Among them,the circular array interferometer is a special two-dimensional direction finding system,which has the characteristics of high probability of unfuzziness and uniform accuracy of direction finding,so it has a broad research prospect in the field of electronic reconnaissance.In practical engineering,when the antenna array is conformal,the antenna installation may be limited by the assembly space.For example,when the installation size of the azimuth plane and the pitching plane are different,the diameter of the circular array interferometer is larger than the installation size of one dimension,which will lead to the array could not be installed.For this kind of application scenario,it is considered to transform the circular array interferometer into an elliptical array interferometer,whose long axis and short axis match the required installation size respectively.The accuracy of direction finding corresponding to the short axis will be reduced,but it is better than that of the linear array interferometer of the same size.When the antenna array is installed on the seeker,wing vertical and other specialshaped surface platforms,there will be a situation that the antenna cannot be installed in a specific position,so the position of the antenna needs to be adjusted flexibly according to the assembly space.In order to meet the assembly requirements of the above two scenarios at the same time,the antenna array is considered to be set as a non-uniform elliptical array,whose array element positions can be flexibly adjusted to the assembly space.Therefore,this paper is established a direction finding model of the inhomogeneous elliptic array interferometer,and the cost function between the position of the array element and the direction finding error is constructed.The position of the array element can be adjusted flexibly according to the value of the cost function,so that the direction finding index and installation layout of the system can be satisfied.Firstly,the basic principle of direction finding and the algorithm of direction finding and dephase blurring are analyzed.From one-dimensional interferometer to twodimensional interferometer,this paper introduces the commonly used algorithm of direction finding and dephase blurring,compares and analyzes the advantages and disadvantages of each algorithm.Then,based on the stereo baseline method,an improved stereo baseline method is proposed to overcome the defects of image blurring and under-utilization of antenna array information.The algorithm uses the idea of K-means clustering algorithm to solve the phase ambiguity,which can make full use of each set of baselines in the antenna array,and solves the image ambiguity problem.Based on the improved stereo baseline method,the direction finding models of uniform circular array and uniform elliptic array interferometer are established,and the direction finding errors of above two arrays are simulated and analyzed,and the effect of the uniform elliptic array interferometer's pitch wikis becoming shorter on the performance of direction finding is analyzed by the simulation results.In this paper,the influence of the position of the array element on the direction finding error of the inhomogeneous elliptic array is analyzed,and the error model is established.The influence of array element position change on the joint measurement error of azimuth Angle and pitch Angle of the system is analyzed concretely,and the antenna installation range with better direction finding performance on the elliptical circumference is calculated,which provides a basis for the arrangement of non-uniform elliptical array.The simulation results of the different direction finding performance of several forms of non-uniform elliptical array verify the correctness of the theoretical analysis.For the uniform circular array,uniform elliptic array and non-uniform elliptic array interferometers established in this paper,the actual measured data of the system are collected,and the test data are substituted into the improved stereo baseline method,which verifies the feasibility of the algorithm and the effectiveness of array analysis.