Array calibration for compensating gain/phase mismatch and mutual coupling effects in Smart Antenna Systems

In smart antenna downlink systems, the beamforming is severely affected by antenna gain and phase mismatch as well as mutual coupling effects. We propose an eigen-structure based approach to estimate the gain and phase of each antenna sensor and mutual coupling coefficients between antenna sensors. By preprocessing the transmission signal in base station with the estimated parameters, the gain and phase mismatch and mutual coupling effects are compensated. Simulation results with data collected from a smart antenna test bed show that the estimation error is less than 5% and correct beam pattern is obtained.