Calculable resistors of coaxial design

Abstract

1000 Ω and 1290.64 Ω coaxial resistors with calculable frequency dependence have been realized at PTB to be used in quantum Hall effect-based impedance measurements. In contradistinction to common designs of coaxial resistors, the design described in this paper makes it possible to remove the resistive element from the shield and to handle it without cutting the outer cylindrical shield of the resistor. Emphasis has been given to manufacturing technology and suppressing unwanted sources of frequency dependence. The adjustment accuracy is better than 10 µΩ Ω−1.

A Simple Methodology to Develop Bifilar, Quadrifilar, and Octofilar Calculable Resistors

“…This linear frequency performance is not expected in the model of CRs of any geometry. Nevertheless, this similar linear frequency behavior was found on CRs and was reported in [26,34]. Some possible causes for this behavior are the bridge with which the measurements were made, the CRs dielectric, and the terminal-wire joining.…”

“…The dielectric in the CRs is not the reason because all the CRs have air as dielectric and were exposed to the same environmental conditions, and the linear frequency dependence is observed only when RC-1k-D is used. The most likely reason is located in the wire or the terminal-wire connections [26], due to damage caused by a very strong blow to the CR container during transport.…”

“…Descriptions of the geometry and the model of the CRs have been described in previous works [1][2][3]25,26]. However, none of those describes details of the construction process.…”

Thermal characterization of a coaxial calculable resistor

“…Furthermore, if the element finds itself under mechanical strain, there can be a slow migration of macroscopic physical properties of the resistor, which may cause long-term drift [5].…”

“…Volatility in the value of this calculable resistor can be caused by the degradation of the resistive element surface on welds, which brings as an immediate effect the increase of the contact resistance at junction points and very likely a reduction of the repetitivity of the measurements. Furthermore, if the element finds itself under mechanical strain, there can be a slow migration of macroscopic physical properties of the resistor, which may cause long-term drift [5].…”