Polarization performances and antenna misalignment errors for aperture arrays: SKA-low AAVS0.5 case

The challenge of the design for the new generation of polarimeters is to evaluate the accuracy in the measurements of the polarization state of an observed source. Different errors can affect this accuracy, including imprecision of the antenna mechanical implementation and uncertainties in the array deploying. We present a study of the two families of misalignments errors expected to affect the array antenna polarization performances of a low frequency irregular aperture array. The case of study is a low frequency aperture array verification system for SKA (Square kilometre Array) named AAVS0.5. Misalignment errors are shown to produce negligible degradation of the IXR (intrinsic cross-polarization ratio) within a large range of tolerance angles.