Improving the primary power standard below 10 MHz with thermoelectric sensors

High frequency power standard is quite everywhere implemented using the microcalorimeter technique. At INRiM a twin type coaxial microcalorimeter is used to measure the effective efficiency of thermoelectric detectors from direct current up to 40 GHz. However, below 10 MHz there is a lack of sensitivity that reduces the power standard accuracy. To work around the problem, we propose to calibrate the power detectors trough RF voltage measurements in the lowest frequency band.