A method of determining the angle of arrival of a signal, the method comprising the steps of: providing a plurality of antennae; sampling, in turn, the output from each of the antennae, to obtain a set of samples, each of the samples relating to different points in time; performing a Fourier transform on the set of samples, thereby producing a sequence of spectral lines; identifying a signal impinging on the antennae from the configuration of the spectral lines; and calculating, from phase and amplitude data gathered from at least a subset of the spectral lines, the direction of arrival of the signal at the antennae. The invention allows high resolution estimation of the directions of arrival of multiple signals with a single channel receiver employing a plurality of antennae which may be spatially separated or provided in substantially the same location as one another. The antenna sampling rate need only be 2N times the bandwidth of the impinging signals (N being the number of antennae), and direction finders operating in accordance with the invention may be inexpensive, compact and high-performance.