Joint Polarization and DOA Estimation Based on Improved Maximum Likelihood Estimator and Performance Analysis for Conformal Array

The conformal array can make full use of the aperture,save space,meet the requirements of aerodynamics,and is sen-sitive to polarization information.It has broad application prospects in military,aerospace,and communication fields.The joint polarization and direction-of-arrival(DOA)estimation based on the conformal array and the theoretical analysis of its para-meter estimation performance are the key factors to promote the engineering application of the conformal array.To solve these problems,this paper establishes the wave field signal model of the conformal array.Then,for the case of a single target,the cost function of the maximum likelihood(ML)estimator is rewrit-ten with Rayleigh quotient from a problem of maximizing the ratio of quadratic forms into those of minimizing quadratic forms.On this basis,rapid parameter estimation is achieved with the idea of manifold separation technology(MST).Compared with the modified variable projection(MVP)algorithm,it reduces the computational complexity and improves the parameter estima-tion performance.Meanwhile,the MST is used to solve the par-tial derivative of the steering vector.Then,the theoretical perfor-mance of ML,the multiple signal classification(MUSIC)estima-tor and Cramer-Rao bound(CRB)based on the conformal array are derived respectively,which provides theoretical foundation for the engineering application of the conformal array.Finally,the simulation experiment verifies the effectiveness of the proposed method.