Combined Calibration Method and its Realization for Direction Finding Antenna Systems with Patch Antennas

Abstract

A novel radio channel compensation method aiming to give optimal calibration for microstrip antenna array systems is presented in this paper, realized for an actual DOA measurement antenna system using microstrip antennas to sample the electromagnetic field, operating at 4.5GHz. This new approach considers mismatch between antennas and channel RF ports, channel transmission inequalities, and also decreases the effects of multipath propagation components of calibration reference signals by placing the calibration reference signal feeding network on the microstrip antenna array bearer, directly beside the antenna patches. It is combined with orthogonal spread spectrum calibration signal utility for continuous uninterrupted measurements. The spread spectrum calibration signal is orthogonal to the continuous wave (CW) signal to be measured, therefore, the 2 signals can be separated in the receiver, enabling them to be present simultaneously. DOA measurement results are shown, measured with the realized integrated microstrip patch antenna array with calibration network hardware.