Optimisation method on conformal array element positions for low sidelobe pattern synthesis

An optimisation method for antenna element positions in conformal arrays is proposed in this study. Owing to the platform effect, the element pattern in a conformal array varies with its location. It is usually very time consuming to simulate the element patterns at all possible locations. In this proposed method, the patterns of an element located at an arbitrary position on the platform are obtained by interpolating the element patterns at several sampled locations using the model-based parameter estimation (MBPE) method. This interpolation strategy consists of two steps. Firstly, it interpolates the Fourier coefficients of the given element patterns at the sampled locations to acquire the Fourier coefficients of the element patterns at the desired location. Then the inverse discrete Fourier transform (IDFT) or the inverse fast Fourier transform (IFFT) algorithm is applied to obtain the element pattern. Compared with the conventional interpolation methods, this interpolation needs much fewer samples in the spatial domain and a smaller number of interpolation parameters. The element layout is optimised by the particle swarm optimisation (PSO) method. For each layout, the array excitations are obtained by the robust convex optimisation method. This proposed method is demonstrated through an optimisation on a cylindrical-parabolic conformal array.