Patent ID: 6897807

Claim:
A radio-wave arrival-direction estimating method comprising: (a) calculating a correlation matrix of signals received by an array antenna including a plurality of the antenna elements by correlation calculation between the antenna elements; (b) calculating a noise spatial eigenmatrix by eigenvalue factorization of the correlation matrix, one of a row and a column of the noise spatial eigenmatrix being an eigenvector belonging to a noise eigen-space; (c) factorizing a matrix including a product of the noise spatial eigenmatrix and a conjugated and transposed matrix of the noise spatial eigenmatrix to a product of one of an upper triangular matrix and a lower triangular matrix; (d) calculating an evaluation value of an arrival-angle evaluation function every predetermined angle, the arrival-angle evaluation function being expressed using the one of the upper triangular matrix and the lower triangular matrix; and (e) determining an arrival angle based on the evaluation value every predetermined angle.