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A wideband non-resonant absorber is proposed, and its radar cross section (RCS) reduction is investigated. A discussion on the functional materials available is followed by the design of an absorber on a Plexiglas substrate with polyaniline-graphene nanocomposite as layered square inclusions with thicknesses and conductivities scaled to golden ratio. The measured dielectric properties of polyaniline-graphene nanocomposites are used in the fullwave simulation. The design parameters have been identified and optimized using CST Microwave Studio. As designed structure is fabricated and the reflection is measured. The objective of the work is to demonstrate the use of non-metallic conducting polymer composites devoid of metals for radar absorbing material (RAM) structural designs. The structure is an all-polymer and electrically thin design with a potential to be 3D printed to suit the target object.

Abstract-A detailed study on the performance of a high impedance surface on lossy dielectric is presented in this paper. It is observed that the structure, which is an array of square loops on a grounded dielectric, behaves as artificial magnetic condutor, narrowband absorber or perfect electric conductor depending on the dielectric loss. An equivalent circuit modelling is used to theoretically explain how this transition is happening. The observed narrowband absorption (bandwidth = 0.08 GHz) of the thin (0.016λ) lossy dielectric is scalable to different operating frequencies by varying the structure parameters. The simulation studies on the effect of structural and dielectric properties on the characteristics of this HIS are also dealt with in this paper. Experimental investigation is in good agreement with simulated result and equivalent circuit modelling.

A material sample of Camphour Sulphonic Acid doped Polyaniline (PANI-CSA) is contemplated towards its conceivable use as a microwave shield. Shielding towards electromagnetic interferences (EMI) is measured over various frequency bands by the waveguide method. Plane wave electromagnetic theory is used to generalize the overall reflection and transmission coefficients of the polymer. EMI shielding of the polymer, in the form of Shielding Efficiency (SE), is analyzed over the microwave frequency range from 2 to 18 GHz, demonstrating the potential value of the polymer as an electromagnetic interference (EMI) shield for commercial purposes. The shielding film is fabricated using standard procedure with CSA as the dopant and m-cresol as the solvent. The shielding effectiveness as high as 45 dB for the sample of PANI doped with CSA is observed.

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