Composite microwave shielding

Parveen Saini (PhD Thesis) Synthesis, Characterization and Evaluation of Conducting Polymer Blends and Composites for Microwave Shielding and Antistatic Application, 2012 (Copyright Indian Institute of Technology, New Delhi, India). 

The radome (radome protective domes) market is also important for ECPE fibers. ECPE composite systems act as a shield that is virtually transparent to microwave signals, even in high-frequency regimes. 

M.Y. Koledintseva, J. Drewniak, R. DuBro, Modeling of shielding composite materials and structures for microwave frequencies. Prog. Electromagn. Res. B IS, 197—215 (2009)... 

K. Lakshmi, H. John, K. T. Mathew, R. Joseph, K. E. George, Microwave Absorption, Reflection and EMI Shielding of PU-PANI Composite. Acta Mater. 2009, 57, 371-375. 

N. H. Hoang, J.-L. Wojkiewicz, J.-L. Miane, R. S. Biscarro, Lightweight Electromagnetic Shields Using Optimized Polyaniline Composites in the Microwave Band. Polym Adv Technol 2007,18, 257-262. 

NR composites were prepared containing both carbon black and graphene. Dielectric and microwave absorption and reflection were characterized to access electromagnetic interference shielding effectiveness. Graphene was shown to be effective as a second filler in NR. ... 

There are many applications where the physical properties of a textile substrate are combined with the electrical and shielding properties of polypyrrole. Thus polypyrrole-coated fabrics show excellent dissipation properties. In this way industrial uniforms where explosion-proof conditions or shielding fi om micro-waves are necessary can be fabricated, as well as the use of polypyrrole-coated filters where static charges could cause the explosion of flammable solvents. Other important applications are related to military equipment, as radar-absorbing sheets. The microwave response of those fabrics seems to be ideal for camouflage nets that avoid visual, near-infrared and radar detection. Textile fabrics have also applications in fiber-reinforced composite structures of different resins. 

For example, blends and semi-IPN of polypyrrole and EPDM rubber, prepared by calendering, absorb 85% of microwave radiation in the 10-13 GHz range [167]. Surface deposition of polypyrrole onto poly-(vinylchloride) produced composites with microwave absorption properties in the 0.1-20 GHz frequency range [168]. The same authors also studied the shielding characteristics of blends of polyaniline and poly(3-octylthiophene) with polystyrene and with the copolymer of ethylene and vinyl acetate. For defense purposes, however, a larger frequency range should be covered, but this only encourages continuation of the research. 

In this study, wood fibers modified with nano-sized magnetite have been developed. They show improved electrical conductivity and microwave adsorption ability. Based on these fibers new polymer composites, with special shielding properties against electromagnetic wave,have been obtained. 

Hoang, N.H., Wojkiewicz, Ji., Miane, Ji., Biscarro, R.S., 2007. Lightweight electromagnetic shields using optimized polyaniline composites in the microwave band. Polymer for Advanced Technology 18, 257—262. 

Cao, M.-S., Song, W.-L., Hou, Z.-L., Wen, B., Yuan, J., 2010. The effects of temperature and frequency on the dielectric properties, electromagnetic interference shielding and microwave-absorption of short carbon fiber/silica composites. Carbon 48, 788—796. 

Lakshmi et al. [31] analyzed the microwave absorption, microwave reflection and EMI shielding properties of PANI-polyurethane composite at the S- and X-band frequencies. The results showed that the maximum EMI SE in S-band occurred at 2.23GHz (-10.2dB at 1.26nnn) while in X-band, the maximum EMI SE occurred at 8.82GHz (-26.7dB at 1.99 mm). 

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