Calibration techniques for digital phased arrays

Several techniques for calibrating and aligning different aspects of a digital phased array are demonstrated using a 16-element, panelized, vertically-polarized S-band subarray with element-level digitization on both transmit and receive. These techniques make use of the element-level functionality not only to expedite the process of initial alignment and calibration but to enhance the ability of the array to maintain and enforce this calibration over time as RF/analog system variations occur. A method for maintaining element amplitude and phase over time in fully digitized arrays is demonstrated as well as a technique for element-level self-calibration of quadrature mismatches.