Application of Spherical Near-Field uncertainty analysis to positioner design

Several methods have been proposed to characterize potential sources of Spherical Near-Field measurement uncertainties, including simulated, empirical, and analytical studies[1][2][3][4]. One of the goals of such work is to understand the degree to which the measured results of a given system should be trusted. Another important benefit can be obtained by applying uncertainty analysis during system design to achieve better performance in the realized system. This paper shows how a Roll over Azimuth positioning system was analyzed to determine the major mechanical contributors to uncertainty in a W-band Spherical Near-Field system. The results of the analysis were used to target specific improvements to components of the positioning system. These changes resulted in better measurements at minimal incremental cost, yet without resorting to the expense of high accuracy position feedback. The relationship between the primary mechanical sources of uncertainty and the quality of the Spherical Near-Field measurement is described. This example illustrates the detailed work behind uncertainty analysis and shows its value in making appropriate design decisions.