On the complete theory of coaxial TEM cells

The paper contains a review of the possibilities of using TEM circular coaxial measuring cells for determining the shielding effectiveness of materials used in EMC. It is an approach to the two cases that may appear in the plane waves region: thin and thick shield (from electrical point of view). Both mathematical isomorphism (the basis of using TEM cells) and measurements errors due to disregarding of theoretical conditions are analysed. Also, is demonstrated the limitation regarding the use of TEM cells for testing thick samples. Theoretical and experimental results are presented.