Alignment Sensitivity and Correction Methods for Millimeter Wave Spherical Near-Field Measurements
Authors: Greg Hindman, Allen Newell, Luciano Dicecca, Jean Christophe Angevain
Millimeter-wave measurements on spherical nearfield scanning systems present a number of technical challenges to be overcome to guarantee accurate measurements are achieved. This paper will focus on the affect of mechanical alignment errors of the spherical rotator system on the antenna’s measured performance. Methods of precision alignment will be reviewed. Sensitivity to induced mechanical alignment errors and their affect on various antenna parameters will be shown and discussed. Correction methods for residual alignment errors will also be described. The study includes 38 and 48 GHz data on the Alphasat EM model offset reflector antenna measured by TeS in Tito, Italy on a NSI-700S-60 Spherical Nearfield system, as well as a 40 GHz waveguide array antenna measured by NSI on a similar NSI-700S-60 Spherical Nearfield System at its factory in Torrance, CA, USA.