In ANSI C63.4 the required antenna is a half wave tuned dipole. There is an allowance that lets a broadband antenna be used provided the results can be correlated to the half wave tuned dipole. When performing radiated emissions testing to CFR 47, Part 15, using ANSI C63.4 the requirement is to height scan the receiving antenna from 1 to 4 meters.
My question concerns the instance where vertical measurements are made at the lower frequencies (below 80 MHz). If the received antenna is height scanned from 1 to 4 meters at these lower frequencies the measured levels will not correlate to a half wave tuned dipole as the worst case vertical levels are typically found at lower antenna heights. It has been my experience that the height scan of the broadband antenna must be limited to the range that the half wave tuned dipole can be scanned over to demonstrate correlation. I would like to have some discussion on this issue to get a feel for how this is being addressed by others. Tom Donnelly EMC Engineer Lucent Technologies tdonne...@lucent.com
