Correlation based characterisation of phased array components

The German SAR satellite TerraSAR is currently under development. The SAR instrument onboard the satellite will be equipped with an array antenna consisting of 384 radiators, each with its own transmit-receive modules (TRM). As usual for this kind of active planar antennas, all TRMs are independently adjustable in phase and gain. To ensure precise knowledge of phase and gain of each TRM also after launch, an in-flight module characterization/calibration capability is implemented within the instrument, following a correlation based approach described by [D. Hounan et al., 2002]. The proposed calibration method allows simultaneous characterization by phase and gain of a large number of TRM or TRM clusters, ideally of all TRMs of the antenna. This paper outlines the characterization method and presents results onto the parameter choice of the characterization algorithm, together with results on achievable characterization accuracy. Also TRM failures are being assessed w.r.t. their effect onto characterization. For such TRMs, actually transmitted signal phase and amplitude do not correspond to commanded phase any longer. The robustness of the estimation against such damage is to be analyzed as well as its ability to detect the non-plausible TRM values.