Embedded Element Patterns in Hierarchical Calibration of Large Distributed Arrays

Large distributed aperture array systems like the Low Frequency Array (LOFAR) and the low-frequency component of the Square Kilometre Array (SKA-LOW) require calibration at station level and at array level. At both levels, use of a priori knowledge of the embedded element patterns (EEPs) of the antennas is needed. In this paper, I propose accuracy requirements for station calibration and absolute calibration of the synthesis array system and assess the level of detail needed in modelling of the EEPs (individual, average or isolated) to meet them.