A reassessment of the measurement uncertainty of the XT-90 twin T dual admittance bridge

The RSRE XT-90 Twin T Dual Admittance Bridge, commonly called the Woods bridge after its designer, operates over the frequency range from 5 to 200 MHz and is capable of measuring each component of an unknown admittance, within the range to 50 pF and/or 0 to 50 mS. Both the developments carried out and the measurement methods used on the bridge in order to produce a reassessment of the bridge measurement uncertainty are described. A simple explanation of the bridge circuit design is included.