RF Impedance Standards and Traceability for Four-Terminal Pair and Related Measurements at frequencies form 1MHz to above 30 MHz

Project Description

There has been no progress on any practical work here as no laboratory currently has significant funding for this activity at frequencies above 10 MHz, which was its original focus. However, in line with the decision of the HF Experts Group meeting in 2000, it was agreed at the HF Experts Meeting in November 2001 that this remains an important area for collaboration in Europe and that this project should be retained to help to co-ordinate the raising of funds and intercomparison activities.

An unsuccessful attempt was made in 2001 to obtain funds from the EC by submitting an ‘Expression of Interest’ (EoI) to the EC Framework V Growth Programme. Despite being given a ‘High’ priority by the EC assessors, it was not retained by the EC as a project.

Work on extending four terminal pair (4-TP) calibrations up to 10 MHz continues at NPL. In the USA, at NIST, there is already a capability for 4-TP up to 10 MHz. As other Euromet laboratories have a 4-TP capability at frequencies up to 1 MHz, the co-ordinator is investigating the possibility and advisability of an intercomparison in the 1 – 10 MHz range as an interim measure.

Final Report 2009-11-03

The project was initially set up to meet the perceived ‘urgent’ need for impedance traceability in the stated frequency range. This has become known as the ‘cross-over’ frequency range, i.e. the range that covers the ‘cross-over’ between radio frequencies (RF) and microwave frequencies, and in which traceable impedance measurements are much more difficult to achieve than at the RF and microwave frequencies on either side. Better traceability is this range is still regarded as being desirable, however, from the start of this project, significant co-operation was prevented by lack of funds.
Partners had applied for and anticipated, with reasonable expectation, to receive funds during the lifetime of this project but, in the event, none were forthcoming. The lack of progress was discussed at a number of TC meetings and it was eventually decided at the HF meeting in Delft on 26-27 April 2007 that the project would be wound up. It was proposed that a similar project would be created if and when practical co-operation, with sufficient funds, became possible.

As stated above, there is still a perceived need for work in this area. In 2008 a number of EURAMET HF NMIs put forward an EMRP proposal that would have covered such work. Some of the discussions on Project 613 fed into this proposal, but it was also not funded as a project. The general perception of the problem here is that while better traceability in this area is certainly desirable, it has never achieved a status of high enough priority or high impact factor when compared with other RF and Microwave co-operation and traceability projects, which have therefore been funded in preference.

Electricity and Magnetism (EM)
Bob Clarke (NPL)
Coordinating Institute
NPL (United Kingdom)
Further Partners