Calibration of Aperture Arrays in Time Domain Using the Simultaneous Perturbation Algorithm

Abstract

Online calibration is desired in antenna arrays of ultrawide bandwidth. This study proposes a time domain calibration method based on the simultaneous perturbation algorithm. Two objective functions were established: power of the received signal at array output; or combination of power and correlation coefficient between the signal at array output and a target signal. For both criteria, the convergence settings require only two measurements at each iteration. One advantage of the method is that the entire signal operation for calibration is performed in the time domain. This is achieved by resolving the effects of distortion on time delay of each channel, which accounts for both amplitude and phase distortions at different frequencies. Therefore, the proposed method significantly increased the calibration efficiency for ultra-wideband antenna arrays. Since time delay coefficients for calibration associated with array elements were determined independently due to characteristic of the simultaneous perturbation, estimation accuracy of the method is tangential to the number of elements in the array, and is mainly dependent on the convergence conditions. This gives the method an additional distinct advantage for calibrating large-scale antenna arrays with ultrawide bandwidth. An estimation accuracy of 99% on time delay adjustments has been achieved and demonstrated.