High-resolution digital beamforming of UWB signals based on Caratheodory representation for delay compensation and array extrapolation

To realize high-resolution digital beamforming (DBF) of ultra-wideband (UWB) signals, we propose a DBF method based on Caratheodory representation for delay compensation and array extrapolation. Delay compensation by Caratheodory representation could achieve high interpolation accuracy while using the single channel sampling technique. Array extrapolation by Caratheodory representation reformulates and extends each snapshot, consequently extends the aperture of the original uniform linear array (ULA) by several times and provides a better real-time performance than the existing aperture extrapolation utilizing vector extrapolation based on the two dimensional autoregressive (2-D AR) model. The UWB linear frequency modulated (LFM) signal is used for simulation analysis. Simulation results demonstrate that the proposed method is featured by a much higher spatial resolution than traditional DBF methods and lower sidelobes than using Lagrange fractional filters.