International organization in electromagnetic metrology and international comparison of RF and microwave standards

The international exchange of information concerning electro-magnetic measurements and standards and arrangements for the international comparison of these standards is fostered by several international organizations and laboratories. These organizations and their objectives are identified in this paper. The history of how the comparisons were organized is reviewed, the results of comparisons made since 1950 are summarized, and current comparison efforts are described. As a result of the comparisons, measurements of the quantities involved that are made in participating laboratories can be related to each other with considerable confidence.