Resolving Manifold Ambiguities for Sparse Array Using Planar Substrates

Aiming to resolve the manifold ambiguities for sparse arrays, a method based on the multiple signal classification (MUSIC) algorithm using planar substrate is proposed. The main reason for spurious MUSIC spectrum is that the steering vector of spurious direction of arrival (DOA) is a linear combination of the steering vectors of true DOAs. The main idea of the proposed method is to add some planar substrates at the front-ends of the elements of an array. The refractive indices and thicknesses of the substrates can be different from each other. This treatment breaks down the linearity which induces the ambiguity of a sparse array. Because the equivalent positions of the elements change for different DOAs after adding the substrates on the array, the spurious peaks will disappear or not overlap on the old peaks. Nevertheless the peaks of the true directions will remain. The spurious peaks can be discriminated according to this feature. Simulation results demonstrate the effectiveness and the feasibility of the method. Meanwhile the simulation results also show that the proposed method can partially resolve the trivial ambiguities even if the true DOA and the spurious DOA are confined to (0^°, 180^°).