Calibration procedure for 2-D MIMO over-the-air multi-probe test system

Multi-probe based systems are an attractive alternative for MIMO over-the-air testing of mobile communication devices. Many studies have been conducted on synthesizing fields inside a test system assuming that each of the probes generates a plane wave arriving in the test zone from the direction of the probe. In most practical systems, this is however not the case due to the near-field effects and scattering contributions from the neighboring probes. This paper presents a calibration procedure to partially compensate those near-field and the scattering effects. This calibration procedure is based on two measurement steps and related data processing, which provide the required excitation coefficients for the probes for enabling the partial compensation of the near-field and scattering effects inside the test zone. The proposed calibration procedure is validated by computer calculations.