Adaptive cancellation of nonstationary interference in HF antenna arrays

The paper statistically analyses and compares temporal variability in the spatial structure of two HF interference signals propagated from known locations via ionospheric channels with different spatial and temporal characteristics. The impact of the particular ionospheric paths propagating HF interference on the cancellation performance of various adaptive beamforming algorithms is investigated using data collected by the receiving antenna array of the Jindalee Facility Alice Springs OTH radar in Alice Springs, Australia. Measurements and analysis statistically confirm that the spatial properties of HF interference signals, and the actual performance improvements gained through the use of adaptive beamforming techniques, are highly dependent on the spatio-temporal characteristics of the prevailing ionospheric circuits linking the particular source location to the receiving array at the selected operating frequency