High accuracy calculable AC-DC transfer standards for the LF-30 MHz frequency range

A model for a calculable AC-DC thermal transfer device is described. It is based on the transmission-line theory, augmented by corrections for skin effect and connection admittance. Experimental verification on four devices shows good to excellent agreement between the calculated and measured results. This enables the establishment of AC-DC transfer standards with total uncertainties ranging from less than 5 p.p.m. at 1 MHz to 100 p.p.m. at 30 MHz. Potential for extension to higher frequencies is discussed