Study On Optimization Design And Failure Diagnosis Of Conformal Antenna Array

Conformal arrays is a significant trend for array signal processing in the new century.Its application brings far-reaching impact on phased array radar,stealth fighters,mobile communication base stations,satellite communications and other fields.For conformal arrays,traditional analysis and synthesis method in array signal processing does not hold any more due to the complicated spatial structure.In this thesis,we focus on the array synthesis,beamforming and failed element diagnosis of conformal arrays.Four main aspects are included:1.Considering the distinct orientation of each element due to the conformal carrier curvature,the universal pattern method for conformal arrays based on Euler Rotation is presented.Computer simulations are carried out to validate the given method.2.Taking the directivity of element into account,the genetic algorithm is used to optimize the element positions of hemispherical array to suppress its sidelobe level.The position of element is represented by the polar coordinates projected in the coordinate plane.Thus,synthesis of sparse hemisphere array is equivalent to the element positions optimization in the circular boundary subject to minimum spacing and fixed aperture constraints.The initial population of the genetic algorithm is constructed based on the uniform concentric ring.The radial margin and residual phase of each ring is used as disturbance quantity to improve degree of freedom for element position optimization.3.In the presence of steering vector mismatch caused by direction deviation of the desired signal,a robust beamforming method based on pl-norm sparse constraint is proposed.The proposed method uses a small spherical uncertainty set to correct the steering vector iteratively.The sparse constraint on sidelobe region of the beam pattern is then imposed to the cost function of Minimum Variance Distortionless Response(MVDR)beamformer.4.With near-field measurements,the sparse Bayesian learning(SBL)is applied to conformal array diagnosis based on reconstruction of the ‘difference' array excitation between the sampled and the real near-field measurements.The difference between the field measured using the failure-free array and the field radiated by the array under test shows the property of sparsity.Therefore,the SBL method can be adopted to solve the underdetermined linear equations.Numerical simulations are conducted to validate the effectiveness and accuracy of the proposed array diagnosis approach.