Using radiation pressure to develop a radio-frequency power measurement technique traceable to the redefined SI

We discuss a power-measurement technique traceable to the International System of Units (SI) based on radiation pressure (or radiation force) inherent in an electromagnetic wave. A measurement of radiation pressure offers the possibility for a power measurement traceable to the kilogram and to Planck's constant through the redefined SI. Towards this goal, we performed measurements of the radiation pressure in a radio-frequency (RF) electromagnetic field at three frequencies (26.5 GHz, 32.5 GHz, and 40.0 GHz) and power levels ranging from 2 W to 25 W using a commercially available mass scale. We show comparisons between the RF power obtained with this technique and those obtained with a conventional power meter. The results in this paper represent the first step towards the realization of a more direct link to RF power within the newly redefined SI.