Improved cylindrical displaced coprime conformal array for 2-D DOA and polarization estimation

Recently, sparse conformal arrays have received lots of attention due to its increased array aperture, improved degrees-of-freedom (DOFs) and reduced mutual coupling compared to uniform conformal arrays. In this article, we devise a new sparse conformal array, referred to as the improved cylindrical displaced coprime conformal array (ICDCCA) for two-dimensional (2-D) direction-of-arrival (DOA) and polarization estimation. Unlike the existing sparse conformal arrays, the ICDCCA consists of multiple two-parallel linear arrays, which are constructed by displacing in parallel one subarray in the prototype coprime array and enlarging its inter-sensor spacings. For the ICDCCA configuration, there are closed-form expressions for the sensor positions, and its number of achievable DOFs can be analytically computed, from which the optimum configurations are obtained. Compared with the existing sparse conformal arrays, the proposed array configuration provides a larger array aperture, a higher number of DOFs, as well as less mutual coupling effects. Numerical results demonstrate the superiority of the ICDCCA over several existing sparse conformal arrays.