The effects of table material on radiated field strength measurement reproducibility at open area test sites

Radiated field strength measurements at open area test sites (OATS) require a nonconductive table to support the equipment under test (EUT). Broadband field strength measurements were performed using tabletops of different materials and thicknesses to investigate the influence of the dielectric properties on the measured field strength. Differences of 10 dB were recorded between fibreglass and wood. Significant differences were also recorded for different woods. It is shown that the differences in the dielectric materials used for the OATS table adversely affect measurement reproducibility between test sites. It is recommended that the dielectric properties of the EUT tabletop be adequately defined in the standards.