We have designed and manufactured a flanged coaxial line as a sample holder for measuring the electromagnetic interference ͑EMI͒ shielding efficiency ͑SE͒ of planar materials in broadband frequency ranges up to 18 GHz. Connecting the samples holder to a vector network analyzer (50 MHzрMр13.5 GHz), we measured the S ͑scattering͒-parameters and the EMI SE of copper ͑Cu͒ as a highly conducting material and emeraldine salt form of polyaniline ͑PAN-ES͒ as an intermediately conducting one. The measured EMI SEs of the materials from 50 MHz to 13.5 GHz were compared with those obtained from the conventional ASTM D4935-99 method and theoretical simulation using dc conductivity. We observed that the EMI SEs measured by using both experimental techniques agree with each other in the common frequency range (50 MHz ϳ1.5 GHz). The EMI shielding characteristics of samples such as the contribution of absorption and reflection to total EMI SE were analyzed through the measured S parameters.

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Electromagnetic interference (EMI) shielding materials of complex type of conductive polypyrrole (PPy) as an intrinsically conducting polymer and silver‐palladium (AgPd) metal compound coated on woven or non‐woven fabrics are synthesized. From dc conductivity and SEM photographs of PPy/fabric complexes, we discuss charge transport mechanism and the homogeneity of coating on the fabrics. The EMI shielding efficiency of PPy/fabric and AgPd/fabric complexes is in the range of 8 ∼ 80 dB depending on the conductivity and the additional Ag vacuum evaporation. The highest EMI shielding efficiency of PPy/fabric complexes vacuum‐evaporated by Ag is ∼80 dB, indicating potential materials for military uses. We propose that PPy/fabrics are excellent RF and microwave absorber because of the relatively high absorbance and low reflectance of the materials. Copyright © 2002 John Wiley & Sons, Ltd.

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