Joint antenna-array calibration and direction of arrival estimation for automotive radars

We present an iterative method for joint antenna-array calibration and direction of arrival estimation using millimeter-wave (mm-Wave) radar operating at 77 GHz. The calibration compensates for antenna-array coupling, and phase and gain errors, and does not require any training data. This method is well suited for applications, such as automotive radars, where multiple antenna elements are packaged on a chip and where offline calibration is either expensive or is not possible. The proposed method is highly effective when the array coupling is a function of direction of arriving waves from the object. The novel optimization method proposed in the paper allows it to be used for a 2D array of any shape. Experiments using real data collected from a four-element array on a single-chip radar demonstrate the viability of the algorithm.