Blind calibration of dense irregular arrays by exploiting multiply-measured nearly-identical spatial frequencies

In this paper, I introduce a novel method for blind calibration of dense irregular arrays on an arbitrary scene. This method exploits the fact that in such arrays, several pairs of antennas may sample almost the same spatial frequency. I demonstrate this method using actual data from a single aperture array station of the Low Frequency Array radio telescope. This example showcases the advantages of blind calibration over calibration based on a source model in actual operating conditions. The results also indicate that the impact of errors introduced by modeling nearly-identical spatial frequencies as being identical may be less than the impact of the commonly made (but wrong) assumption that all antennas have the same radiation pattern. The proposed method could thus be an interesting alternative for calibration of the very compact Low Frequency Aperture Array stations of the Square Kilometre Array.