Low distortion positioning equipment for mobile antenna pattern measurements

Two positioning equipment designs for low gain antenna measurements over a solid angle of a sphere has been developed. Careful design of the roll-over-azimuth positioner minimizes the distortions of the antenna radiation pattern. To evaluate the error introduced by the positioning systems, the radiation patterns obtained with each positioner were compared to the one measured in free space. The maximum discrepancy introduced by the positioning mechanisms was found to be about 0.5 dB for both positioners. The error of the radiation power measurement was less than 2 %. The results obtained are considered to be satisfactory.