This chapter discussed all the concepts and devices described so far to show how they may be combined to make practical high-accuracy bridges. The number of networks that may be devised is endless, and therefore, we have chosen just those examples that either are of considerable practical importance to national standards laboratories or illustrate the use of some device or concept. In principle, we show how to relate like impedances of different values and then how to generate the impedance standards of R, L and M from the unit of capacitance. The reader should feel encouraged to devise other networks to serve other special needs. We will often present a network as an admittance bridge; of course the distinction between this and an impedance bridge is purely one of algebraic convenience.

Chapter Contents:

• 9.1 Bridges to measure the ratio of like impedances
• 9.1.1 A two-terminal IVD bridge
• 9.1.2 A two-terminal-pair IVD bridge
• 9.1.3 A four-terminal-pair IVD bridge
• 9.1.4 A two-terminal-pair bridge based on a 10:-1 voltage ratio transformer
• 9.1.5 A four-terminal-pair bridge based on a two-stage 10:-1 voltage ratio transformer
• 9.1.6 Equal-power resistance bridge
• 9.2 Bridges to measure the ratio of unlike impedances
• 9.2.1 R-C: the quadrature bridge
• 9.2.2 The quadrature bridge - a two-terminal-pair design
• 9.2.3 The quadrature bridge - a four-terminal-pair design
• 9.2.4 Bridges for measuring inductance
• 9.3 AC measurement of quantum Hall resistance
• 9.3.1 AC contact resistance
• 9.3.2 AC longitudinal resistance
• 9.3.3 Measuring R xxLo
• 9.3.4 Measuring R xxHi
• 9.3.5 A simple coaxial bridge for measuring non-decade capacitances
• 9.3.6 Coaxial resistance ratio bridges involving quantum Hall devices
• 9.3.7 A quadrature bridge with two quantum Hall devices
• 9.4 High-frequency networks
• 9.4.1 An IVD-based bridge for comparing 10:1 ratios of impedance from 10 kHz to 1 MHz
• 9.4.2 A bridge for measuring impedance from 10 kHz to 1 MHz based on a 10:-1 voltage ratio transformer
• 9.4.3 Quasi-four-terminal-pair 1:1 and 10:1 ratio bridges for comparing similar impedances from 0.5 to 10 MHz
• 9.4.4 A four-terminal-pair 10-MHz 1:1 resistance ratio bridge
• 9.4.5 A 1.6- and 16-MHz quadrature bridge
• 9.4.6 Four-terminal-pair resonance frequency measurement of capacitors
• 9.4.7 Scattering parameter measurements and the link to microwave measurements
• 9.4.8 Electronic four-terminal-pair impedance-measuring instruments
• References

Inspec keywords: electric impedance measurement; bridge circuits

Other keywords: impedance ratio meaaurement; coaxial electrical circuits; bridge network; admittance bridge; interference-free measurements

Subjects: Impedance and admittance measurement