Auto-calibrating adaptive array for mobile telecommunications

A major concern for adaptive antennas is the calibration of hardware. Here we consider the calibration of an analog beamformer (ABF), which calculates the weights in a digital signal processor (DSP), but weights the RF signals using a hardware beamformer. Two novel methods are presented of performing a calibration of this adaptive antenna during normal operation. This will mitigate temperature drift and aging of active components. Both methods uses a feedback of the beamformer output signal, to calculate the error in the beamformer output or to identify the parameters in the temperature drift. The algorithms are transparent to normal antenna operation and are computationally simple. Simulations show that when using these auto-calibration methods, the performance is independent of variation in hardware parameters when a realistic temperature drift is introduced. The proposed algorithms are intended for use in a time-division multiple access (TDMA) mobile telephone system, but the methods are applicable in radar systems also.