A practical approach for calibration of MMW MIMO near-field imaging

Abstract

Near-field millimeter-wave (MMW) imaging techniques typically employ multiple-input-multiple-output (MIMO) arrays to obtain high-resolution images. However, the image quality can be seriously affected by array miscalibration. In this paper, a simple and efficient calibration method for MMW MIMO arrays is proposed and validated with real data. The approach makes use of a metal plate as a reference target to collect data in the presence and absence of the reference target. By processing the two sets of received data, we can reduce the effects of inter-channel coupling and environmental interference. The method calculates the reflected position and transmission distance of the electromagnetic wave based on the transmission model of the electromagnetic wave by the metal plate. And the transmission distance difference of all transceiver pairs is eliminated. Then, the delay error and phase error between the channels are successively calculated. Numerical simulations and real measured data are processed to validate the proposed calibration method. The results demonstrate that it is an effective tool for calibrating MMW MIMO arrays.