Direction Finding with Sparse Digital Arrays Based on van der Corput Sequence

Physically large digital beamformers offer higher resolution, but since the cost is proportional to the number of elements in the array, designers try to minimize the number of elements by creating sparse arrays. Larger element spacing however results in grating lobes which in direction finding results in false signal detection. Aperiodic spacing can reduce the grating lobes, however random approaches typically increase the variation in element density. This paper explores the use of nonuniform element spacing based on the hierarchical, low-discrepancy van der Corput sequence for direction finding with sparse digital arrays. Numerical results are presented for linear arrays with average element spacings of one wavelength and taking into account multiple noise cases. We show that the proposed approach is capable of accurate direction finding with sparse arrays and provides a more uniform distribution compared to an equal set of uncorrelated random points.