Analysis and Design of Nonuniform Arrays for Direction Finding

The purpose of this research is to employ non-uniform arrays in different active and passive sensing applications for both narrowband and wideband operations, while providing a multitude of array processing methodologies that assist in dealing with the different encountered challenges. The problem of direction-of-arrival (DOA) estimation using non-uniform arrays is considered. The different challenges that are treated include the reduction of the available degrees-of-freedom (DOFs), the presence of coherent targets, and the mutual coupling effect in practical antenna arrays. Multi-frequency operation is exploited to increase the DOFs that are available for DOA estimation using both high-resolution subspace and sparse reconstruction techniques. In addition, a sparsity-based interpolation technique is presented to perform DOA estimation with increased DOFs. Moreover, a DOA estimation approach for a mixture of coherent and uncorrelated targets based on sparse reconstruction and active non-uniform arrays under narrowband signal platform is proposed. The aforementioned approaches deal with ideal operational scenarios. To address a more practical scenario, various methods for DOA estimation using non-uniform arrays in the presence of mutual coupling are presented. Extensive numerical simulations which validate the different proposed methods are also included.Comment: Ph.D. Dissertatio

Special issue on Co-prime sampling and arrays

Co-prime sampling and co-prime arrays have recently been shown to improve active and passive sensing in radar and under-water acoustics using both narrowband and wideband signal plat-forms. Co-prime processing provides a systematical framework for sparse sampling and array configuration with increased aperture and improved spatial resolution. Co-prime based approaches to sampling and arrays can combat ambiguity and provide unique answers to target coordinates under forced coarse sampling in time, frequency, and space. Temporal and spatial co-prime samplings make advances in direction-of-arrival (DOA) estimation, spectrum sensing, and sparse covariance sketching. They find broad applications in synthetic aperture radar (SAR), radio frequency (RF) surveillance, target localization, wideband urban radar processing, space–time adaptive processing, and nonstationary array processing utilizing Doppler signatures and instantaneous frequency source characteristics