Low Frequency Equivalent Circuit of Dual TEM Cell for Shielding Material Measurement

Atsuhiro NISHIKATA  Ryusuke SAITO  Yukio YAMANAKA  

IEICE TRANSACTIONS on Electronics   Vol.E89-C   No.1   pp.44-50
Publication Date: 2006/01/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.1.44
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Near-Field and Far-Field Electromagnetic Absorption and Shielding and Related Technologies)
shielding material,  shielding effectiveness measurement,  dual TEM cell,  equivalent circuit,  

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To clarify the correspondence between Shielding Effectiveness (SE) of shielding materials and their physical property, we propose an equivalent circuit for a shielding effectiveness test apparatus using a dual TEM cell, and show its validity. By considering the structure of dual TEM cell that consists of a pair of cells coupled via an aperture in their common wall, we defined the capacitance C and mutual inductance M, that respectively express the electric coupling and magnetic coupling between two center conductors. By the measurement of unloaded S-parameter, we determined the values of C and M for a dual TEM cell in hand. Next, the shielding material was approximated by the apparent sheet resistivity Rs, and was used in the equivalent circuit of loaded aperture. As a result, the coupling level calculated from the equivalent circuit agreed well with the measured data in frequencies below 300 MHz.