Total-radiated-power-based OATS-equivalent emissions testing in reverberation chambers and GTEM cells

Reverberation chambers historically have been used for military and aerospace radiated immunity testing, but their use for commercial radiated emissions testing is attracting attention. In contrast to the usual open-area-test-site-type radiated-emissions test, which measures electric field at some distance, a reverb chamber measures the total radiated power from an equipment-under-test. The widely used GTEM cell three-position emissions test method is also based on a total-radiated-power measurement. This paper presents preliminary total radiated power measured from dipole and slotted-box radiators in GTEM cells and reverberation chambers in the 80-1000 MHz frequency range. Measured results for typical multiposition GTEM-to-OATS and free-space correlation schemes are presented. An EUT directivity estimation scheme for power-to-field conversion is reviewed and compared to the GTEM algorithm using data from the same canonical radiators. FDTD-calculated free-space directivity for a slotted-box radiator is compared to the theory. Good agreement is shown between the various facilities