Estimation of arrival modes of multipath signals in the tropical evaporation duct

The angle-of-arrival (AoA) of a microwave radio signal propagating via the tropical evaporation duct contains useful information about propagation modes that support transmission well beyond the nominal radio horizon within the region above a warm ocean surface. The characterisation of propagation modes using the AoA has important applications in interference management and target detection/ranging. Fourier domain algorithms have been used for AoA estimation in this application, but the study of complex propagation modes mandates the investigation of higher resolution algorithms. The University of Canberra Radio Spectrum Research Group (RSRG) is constructing a 16 element linear array, capable of resolving complex duct structures using AoA. Initially using Fourier domain methods, an AoA estimation algorithm based on subspace eigen analysis is to be investigated and compared. Other methods that may be considered include statistical signal characterisation and the wavelet transform.