Superdirective Beamforming Method for Cylindrical Arrays Based on Eigenbeam Decomposition and Synthesis

To apply the small-aperture sensor array with relatively high spatial directivity to the space-limited unmanned undersea systems or other platforms, the superdirective beamforming method is used to improve the spatial directivity and array gains of the sensor array, and the target detection performance of the array is improved. First, a superdirective beamforming method based on eigenbeam decomposition and synthesis(EBDS) for circular arrays is introduced; then, a superdirective beamforming model for cylindrical arrays is proposed by using two-level subarrays at arbitrary pitch direction, and the noise cross-spectral matrix with circulant property in the isotropic noise field is derived. Simulation results of beampatterns and array gains show that the proposed superdirective beamforming method has many advantages over the conventional beamforming method in the directivity and the array gain at low frequency, which extends the application scope of cylindrical arrays with the EBDS and enhances the detection ability of cylindrical arrays. This study may provide a reference for application of small-aperture sensor array to detection of unmanned undersea systems at low frequency.