Evaluation Of EMC Disturbance Tests Uncertainty

The uncertainty of electromagnetic compatibility testing is an important question arisen in the resent years in EMC field. Measurement uncertainty is a quantity sign of the result of measurement, the usage of the result is mostly depends on the magnitude of the uncertainty. For EMC test, the uncertainty is a parameter associated with the result of a measurement, and it reflects the level of tests, the advanced of test equipment and ability of the test engineers, and also effects the test results. As an EMC test lab, for the inter-laboratory comparisons and accept the reports each other, laboratory should pass the certification .It is a very important requirement which is the report should include evaluating uncertainty.Base on the experience in EMC tests and test standards, together with the writer's own understanding in uncertainty; this paper explores the general method to evaluate uncertainty in EMC measurement, and discusses in detail the evaluation of uncertainty for some EMC disturbance tests of Tianjin Radio Monitoring Station EMC lab, especially for the radiate emission test for 1GHz-18GHz, which is not prescribed by any standard.At first the basic concepts and history of uncertainty is introduced, then the general process to evaluate uncertainty in EMC disturbance test is presented, at last the detailed analysis of uncertainty in radiated disturbance test, conducted disturbance and the radiate power test. In the end of this paper, the main difficulties in evaluation of uncertainty in EMC measurement are summed up.