Verification of THEA Tile Calibration and Beamforming Results using a Near Field Scanner

ASTRON is in the process of realizing phased array technology for the Square Kilometer Array (SKA). A demonstrator known as the THousand Element Array (THEA) is currently under construction to develop such technology. One of the 16 phased array tiles from which THEA is built, is reported in this paper. Each tile can be calibrated using a Phase Toggling Technique developed previously. The only verification of such a processes were possible by measuring beam patterns. This paper illustrates the use of a recently installed Planar Near Field Scanner to perform the verification using holography measurements. Additionally the scanner provides far field beam patterns, which are also presented. An important part of SKA technology is the ability to reject RFI signals, which is demonstrated using deterministic nulling techniques. These results are also illustrated.