RF Voltage Difference Between Two Outputs of a Tee in the Calibration of TVCs to 1 MHz

In the calibration of a thermal voltage converter (TVC), a symmetrical or asymmetrical Tee is internally or externally used. A primary ac-dc transfer standard and a TVC under test are connected to the two outputs of the Tee. In this paper, the effect of reflections of the primary ac-dc transfer standard and the TVC under test as well as the Tee is considered. The expression of the voltage difference between the two output ports of the Tee is obtained using the signal flow graph. Scattering parameters of all devices are measured using a vector network analyzer (VNA). Results show that the voltage difference is within 0.017% in the frequency range of 100 Hz to 1 MHz, which will be used as one of uncertainty sources in the calibration of diode power sensors.