To provide an arrival direction estimator for applying a forward/backward average method even if antenna elements are circularly arrayed, suppressing an effect due to a noise, and estimating arrival directions of coherent waves.
A calculation means 30 calculates a projection matrix for indicating the degree of contributions of the antenna elements 1-7 for receiving only the L coherent waves based on a signal received by an array antenna 10 when the array antenna 10 is switched to a plurality of directional characteristics. A direction estimating means 40 applies the forward/backward average method in a state of the antenna elements 1-7 to be linearly converted based on the projection matrix, calculates a correlation matrix for indicating correlations of the L coherent waves, converts the calculated correlation matrix into an average correlation matrix when the antenna elements 1-7 is circularly arrayed, applies a ESPRIT method, and estimates the arrival directions of the L coherent waves.
MICKAEL PENCOLE
OHIRA TAKASHI
Takao Matsuyama