Primary Standard of Attenuation in the Frequency Range of 1 kHz to 10 MHz

Primary standard of attenuation in the frequency range of 1 kHz to 10 MHz is developed to meet the demands in recent EMC regulations that require traceability of measurements to national standards. A null detection system with an IVD as a reference standard is constructed to allow attenuation at 1 kHz, 9 kHz, and 10 kHz to be measured accurately by comparing to the voltage ratio of the IVD. Attenuation in the frequency range of 100 kHz to 10 MHz is measured in the same procedure after being down converted to 1 kHz using heterodyne detection technique. A double step technique is introduced in measurements at 9 kHz and 10kHz to keep high accuracy results due to increasing of the IVD uncertainties. Higher dynamic range is obtained by installing toroidal ferrite chokes in the system to minimize common-mode leakages in the kilohertz frequency range. The measurement capability is expected to be larger than 60 dB with the expanded uncertainty range starting from 0.0016 dB.