Angle Estimation Using Wideband Frequency Modulation and an Active Distributed Array

A new method of target angle estimation, which leverages wideband waveforms and a distributed array receiver, is presented. The distributed array receiver generates a grating lobe pattern, the spatially distributed phase of which changes as a function of frequency. By implementing a wideband linear frequency modulated waveform, a phase response manifests in the distributed array receiver output, whose instantaneous frequency is proportional to the angle of the object. The receiver frequency response is derived, and the angle estimation approach is experimentally demonstrated. A 4.8-GHz distributed array radar was implemented with a receiver baseline of 19.36λ using a waveform modulated over 2 GHz of bandwidth. Measurements with a single-point target were conducted, and the measured frequency responses show the expected correspondence to the angle of the target with an average error of 2.8° (0.049 rad) and a standard deviation of 1.8° (0.031 rad).