High Performance Implementation of Nested Array Beamformer for Wideband Radar Applications Beamformer is an important part of the wideband radar systems. An approach to achieve the high sampling rate required in such systems is to use efficient hardware implementations. This paper presents a speed optimized systolic arrays for implementation of the wideband beamformer using nested arrays, 2D filters, and multirate techniques. The implementation structures of the beamformer basic building blocks are designed based on systematic methodology and implemented using the field programmable gate array (FPGA) platform targeting Basys 3 development boardxe2x80x99s Xilinx Artix7 (XC7A100T) FPGA chip. A single channel of the beamformer was chosen for the implementation to confirm the correct functionality of the FPGA architecture. The implementation performance is tested in terms of effect of errors due to finite wordlength arithmetic.

DOA Estimation Using FourthOrder Cumulants in Nested Arrays with Structured Imperfections Recently developed super nested array families have drawn much attention owing to their merits on keeping the benefits of the standard nested arrays while further mitigating coupling in dense subarray portions. In this communication, a new mutual coupling model for nested arrays is constructed. Analyzing the structure of the newly formed mutual coupling matrix, a transformation of the distorted steering vector to separate angular information from the mutual coupling coefficients is revealed. By this property, direction of arrival (DOA) estimates can be determined via a grid search for the minimum of a determinant function of DOA, which is induced by the rank reduction property. We also extend the robust DOA estimation method to accommodate the unknown mutual coupling and gainphase mismatches in the nested array. Compared with the schemes of super nested array families on reducing the mutual coupling effects, the solutions presented in this paper has two advantages: (a) It is applicable to the standard nested arrays without rearranging the configuration to increase the interelement spacing, alleviating the cross talk in dense uniform linear arrays (ULAs) as well as gainphase errors in sparse ULA parts; (b) Perturbations in nested arrays are estimated in colored noise, which is significant but rarely discussed before. Simulations results corroborate the superiority of the proposed methods using fourthorder cumulants.