A calibration technique for active phased array antennas

In active phased array antennas, transmit and receive functions are distributed at the aperture using transmit and receive (T/R) modules. Active phased arrays are typically calibrated in a near-field antenna range at the factory. The performance of active phased array antennas would degrade over time due to changes in the characteristics of active devices and would require recalibration in the field. In this paper, we present a calibration technique for active phased array antennas that uses a small number of passive array elements dedicated to calibration. The dedicated calibration elements are passive in that they do not have T/R modules behind them. The measured mutual coupling data in the field are compared with the measured data at the factory.