Calibration and use of artificial mains networks and absorbing clamps

Proper use of transducers for CISPR-based emissions measurements

Executive summary of project


1. Introduction

2. Summary of results and best practice recommendations

2.1. AMNs/LISNs

2.1.1. Results

2.1.2. Use

2.1.3. Calibration

2.1.4. Design of unit

2.2. Absorbing clamps

2.2.1. Results

2.2.2. Use

2.2.3. Calibration

2.2.4. Design of unit



The report of which this document is a summary has been written to advise test engineers and others on the best practice techniques for the use and calibration of transducers for RF conducted emissions and disturbance power measurements. These measurements are inherent in many European EMC standards that are based on the CISPR emissions methods, and form an important part of testing to meet the compliance requirements of the European EMC Directive. There are two particular aspects of these tests which are of great relevance to equipment manufacturers who must make a declaration of compliance based on the test results:

These factors are directly affected by a number of parameters that relate to the test method and the test equipment. Among them are the calibration and method of use of the transducers. Of these transducers, the most important are the artificial mains network (AMN) or line impedance stabilising network (LISN) for the conducted emissions test on the mains lead up to 30MHz, and the absorbing clamp for the disturbance power test on the mains and other leads above 30MHz. The document therefore sets out best practice in the use and calibration of these items, with the intent of minimising uncertainties which can be attributed to these particular aspects.

The project of which the document is the result has drawn on a number of sources of information:

This programme of work was carried out by the partners in the project, Schaffner Chase EMC and the National Physical Laboratory, both of whom are accredited by UKAS to perform these types of calibration.

Summary of results and best practice recommendations

These recommendations result from our investigations as described in the main part of this guide, as well as other sources that are referenced where relevant. They are presented roughly in order of priority. The comments are intended to amplify the instructions contained in the various CISPR standards; test procedures and design aspects that are already commonplace or typical are not discussed.



The anticipated contributions to measurement uncertainty for calibration of and testing with the standard CISPR 16-1 AMN/LISN have been systematically investigated. The uncertainties referred to below are expanded uncertainties for k = 2. The investigation has shown that

The investigation has made it possible to recommend improvements to best practice in testing and calibration, and certain changes to the design of commercial AMN/LISNs.



Design of unit

Absorbing clamps


The expected uncertainty contributions for calibration of and testing with the CISPR 16-1 absorbing clamp have been investigated. The results are:

The investigation has made it possible to clarify the important parameters in the test and calibration setups and methods, and to recommend some improvements to best practice in testing and calibration.



Design of unit