An improved null steering algorithm for polarised VLF

A new algorithm is presented for electronically steering a crossed-loop VLF receiver antenna array to remove interference. The algorithm is a modification of the eigenvector sorting algorithm, which exploits spatial correlation statistics. The new algorithm is intended for situations where the wanted signal is from a transmitter at close range and therefore has horizontal circular polarisation, but the interferer is from a long range and so has linear polarisation. Exploiting the difference in polarisation by discarding the imaginary part of the correlation matrix, allows accurate null steering even when the interferer is of equal power to the wanted signal. The algorithm can also separate the differently polarised signals when they come from the same direction