2-Terminal Coaxial Capacitance Measurements and Cable Corrections

TL;DR

This paper discusses the precise measurement of coaxial capacitance using 2-terminal bridge methods, emphasizing the importance of cable and connector corrections for achieving high accuracy in metrological applications.

Contribution

It details the current methods used at Inmetro to measure and calculate correction factors for coaxial capacitance measurements with high precision.

Findings

Correction factors are essential for accurate capacitance measurement.

Methods to measure and calculate correction factors are outlined.

Uncertainties in measurements can be minimized with proper corrections.

Abstract

Coaxial 2-terminal bridge comparison is a widely used metrological method in the dissemination of value of capacitance up to 1000 pF and $10^4$ rad/s. In this range, capacitance can be measured with uncertainties as small as few parts in $10^{7}$; however, such measuments must take into account the corrections due to the impedance of cables, connectors and ports, which can tipically amount up to $10^{-8}$ $\mu$F/F $-$ and maybe larger. In this work, we report on how correction factors in 2-terminal pair coaxial bridge capacitance measurements are presently measured and calculated at Inmetro.