Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
563889 | Signal Processing | 2014 | 7 Pages |
•Filter-and-sum beamforming for broadband linear arrays is addressed.•Oversteering is exploited to generate end-fire frequency-invariant beam patterns.•Optimum constrained directivity is achieved at the lower bound of the frequency band.•A better frequency invariance than in traditional broadband beamforming is achieved.
The end-fire steering of a data-independent beamformer is well suited to achieving superdirective performance by a linear array whose aperture is shorter than the wavelength. Here, we focus on frequency-invariant beam patterns obtained by filter-and-sum beamformers that are robust against errors and fluctuations. We demonstrate that the oversteering technique applied to a weakly directive beam pattern can considerably increase the directivity, providing a frequency invariance that is better than those of traditional methods. The performance is evaluated with respect to the maximum constrained directivity that a given array can provide at the lower bound of the frequency band.