Pattern-reconfigurable sparse array synthesis with minimum element spacing constraint

Due to the coupling effects caused by closely spaced array elements, the minimum spacing constraint is introduced into the synthesis of a multiple-pattern sparse array, and a low-complexity off-grid sparse reconstruction algorithm is applied to achieve precise array element position. The auxiliary weighted vector with spacing constraint is incorporated into the off-grid synthesis problem, transforming the initial l0-norm optimization into the mixed l0/l1-norm optimization, and a sequential alternating iteration (SAI) method has been presented to approach the optimization problems. In addition, convex optimization is employed to simultaneously obtain offsets to decrease reconstruction errors in different beam patterns. The experimental results show that the SAI method achieves the desired antenna patterns for multiple scanning angles through the optimal arrangement of sparse array elements while ensuring sufficient array element spacing. Compared to the previous method, the pattern error is reduced by 16.67% and the sparsity is increased by 20%.