Session Chair: Konstantin Rozanov, Institute for Theoretical and Applied Electromagnetics Session Chair: Sergei A. Tretyakov, Aalto University
10:30am - 11:00am Invited
Design of Ultra Wide-Bandwidth Electromagnetic Wave Absorbers Using Frequency Selective Surfaces with Different Patterns and Geometries
Tian LIU, Sung-Soo KIM
Chungbuk National University, South Korea
A significant challenge in the design of electromagnetic wave absorbers is the acquisition of wide bandwidth absorption properties for commercial and military applications. In addition, a planar layer and a small layer thickness is preferred for convenience in installing and operating the absorbers. The simplest method of constructing a nonmagnetic absorber is Salisbury screen where a homogenous resistive sheet is placed at a position of quarter of wavelength in front of the perfect conducting ground plane. The bandwidth can be increased through adding more resistive sheets to the medium, separated from each other, in order to construct a Jaumann absorber. Replacement of the resistive sheets in the Salisbury screen or Jaumann absorbers with materials that contain capacitance and inductance (such as frequency selective surface) provides added scope for creating broadband absorbers. In this study, a reliable and efficient analytical method is presented for the design of broadband absorbers through layering two frequency selective surfaces (FSS) with different patterns (square loop, patch) and geometries on a grounded dielectric substrate. The circuit parameters of inductance and capacitance of the FSS are retrieved using the equivalent circuit model and utilized in the design of the wide-bandwidth absorbers. The optimal design for the surface resistance of the FSS and the spacer thickness of the double-layer absorber provides a very large absorption bandwidth and a small total thickness. For FSS of square-loop geometry, for instance, a 10 dB absorption bandwidth is predicted to be 5.2–38.3 GHz with a very small total thickness of the absorber (6.3 mm), which is very close to the theoretical limit. Admittance analysis for the substrate (layer thickness) and FSS (patterns, geometries) has been made for the design scheme of the ultra wide-bandwidth absorber.
11:00am - 11:30am Invited
A Multiscale Simulation Approach to Design and Optimize Polymer-Based Photonic Devices
1University of Sherbrooke, Canada; 2University of Science and Technology - Mohamed Boudiaf, Algeria; 3Faculty of Science of Nature and Life, Ibn Khaldoun University, Algeria
Solar shielding materials and devices are highly attractive for different applications such as contact lenses, heat mirrors and thermal insulators in automobiles and buildings. The shielding of solar radiation prevents the increase of temperature inside automotive cabins, improves the comfort of passengers and reduces the use of air conditioning. For this purpose, significant efforts have been made to investigate different thin film materials with excellent transparency and a strong IR-shielding ability. To overcome some of inherent drawbacks, polymer-ITO nano-composites are a promising alternative. They allow radio wave permeability while maintaining strong IR-shielding ability. Thanks to their high physical performances such as lightweight, flexibility, good mechanical strength, durability, and low production cost, polymeric materials are interesting candidates to address these issues. Moreover, their high processability in different shapes such as thin films, is definitively an additional asset. Among the huge number of existing polymers, transparent ones are natural candidates to be used in developing optical devices. However, additional constraints must be put forward such as refractive indices between 1.70 and 1.30, thermal stability and stress birefringence. A specific strategy to design and optimize polymer-based optical devices with high transparency and high NIR reflectivity is thus required. In this presentation, we propose a very efficient multiscale simulation approach to address this issue. The simulation approach combines classical molecular mechanics, and linear scaling-DFT in order to get full description of the optical properties of polymers over a large wavelength range. At each step of the procedure, validation with experimental data is carried out, confirming the accuracy of the approach. The resulting optical constants make possible the design of a multilayer photonic heterostructure specifically patterned for UV/NIR-radiations protection. This device exhibits a transparency higher than 90% in the visible range and shows high UV absorbance. Moreover, a strong NIR-shielding ability of 96% is achieved.
11:30am - 11:45am Oral
Thin Metamaterial EM Wave Absorbers Using Metal Wire Array Structure
1University of Hyogo, Japan; 2Hiroshima University, Japan
Recently, Electromagnetic (EM) wave absorber design methods by fabricating resonator on the circuit substrate (FR4) are proposed. In this study, the authors are proposed the thin EM wave absorber design method using permittivity resonant dispersion of the metal wire array structure on the foamed plastic layer. The reflection characteristics of proposed EM wave absorbers are considered by measurement in free space and by transmission line calculation in microwave frequency range.
11:45am - 12:00pm Oral
An Insight into the In-Situ Melt Blended Flexible Hybrid Nanocomposites to Unveil its Superior Electromagnetic Interference Shielding Effectiveness and Electro-Mechanical Properties
Indian Institute of Technology, Kharagpur, India
Fabrication of high-performance electromagnetic interference shielding efficient (EMI SE) polymer-graphene nanocomposites is very challenging approach against electromagnetic effluence. This work mainly accentuates on the preparation of in-situ reduced graphene oxide (IrGO) through in-situ melt blending of ethylene methyl acrylate (EMA) and graphene oxide (GO) to accomplish superior shielding efficiency (SE) with controlled electro-mechanical properties of the composites. It encompasses the reduction mechanism of GO within polymer matrices, where efficacy highly influenced by methodologies, polymer chemistry as well as the processing parameters. Only 5 wt% IrGO improves shielding efficiency of the composites up to ca. 30 dB over the X band frequency range of 8.2 – 12.4 GHz. This hybrid nanocomposite fashioned 3D conductive network through segregated architecture in the matrix to commit lower conductive percolation with remarkable mechanical strength for its structural integrity. We believe this promising strategy of developing single step EMA-in-situ rGO (EIrGO) nanocomposites of enhanced shielding effectiveness and amendable electro-mechanical properties can endorse large scale production in techno-commercial applications.