Alignment procedures for planar near-field positioners

The alignment of a planar near-field scanner is important for achieving low phase error in measurements and, hence, good pattern data. Non-planarity phase errors can be measured and removed in the data-collection software. However, better mechanical alignment translates into better sidelobe measurements and a higher frequency of operation. This paper describes a procedure for installation and alignment of a planar-scanner positioner, and illustrates the procedure using a box-frame-type scanner. Alignment of the scan plane is independent of the drive system used, since the positional errors associated with the drive system are defined as positional errors.