A novel application of transmission line theory in EMC assessment

Products containing electronics must generally be tested for electromagnetic susceptibility, as part of their EMC certification process, at the end of their development cycle to ensure that the test is of any future use of the product. However the earlier that the product as a whole, or the electronic systems that form part of the product, can be tested for susceptibility, the more benefit, in terms of cost savings, can be gained. In the automotive industry, system-level testing can be used successfully by using a statistical technique to correlate results with the mandatory vehicle-level sign-off test. To test a whole vehicle early in its development would require the use of numerical electromagnetic modelling techniques. Due to lack of success in this area to date, there has been very little usage for EMC evaluation purposes. Based on transmission line theory and a similar statistical technique to that used successfully in system-level testing, a method is presented which could use real vehicle design data to generate both guidelines for designers and data for use in system-level tests. Initial results from a project to develop the method are also presented