scholarly journals Improvement of Microwave Absorbance of Polymer Composites of W-Type Hexaferrite Powders by Attachment of Frequency Selective Surface

2017 ◽  
Vol 62 (2) ◽  
pp. 1325-1328
Author(s):  
H.-S. Cho ◽  
S.-S. Kim
Keyword(s):  
Reflection Loss ◽  
Electromagnetic Waves ◽  
Polymer Matrix Composites ◽  
Magnetic Loss ◽  
Frequency Selective Surface ◽  
Substrate Material ◽  
Matrix Composites ◽  
Frequency Selective ◽  
Ferrite Composites ◽  
Minimum Reflection Loss

AbstractThis work investigates the effect of a frequency selective surface (FSS) composed of a regular array of square loop elements on the absorption properties of grounded ferrite composites. Polymer matrix composites of CoZnW hexaferrite powders having small magnetic loss were used as the substrate material. Computational tools were used to model the interaction between electromagnetic waves and materials and determine the reflection coefficient. Reflection loss and bandwidth were greatly improved by attaching an FSS with controlled electrical resistance (R) onto the grounded ferrite composites. For the FSS withR= 800 Ω, the minimum reflection loss decreased to −25 dB at 10 GHz and the bandwidth was broadened to 7.5-12.5 GHz with respect to −10 dB reflection loss.

scholarly journals Ultrawide Bandwidth Electromagnetic Wave Absorbers Using a High-capacitive Folded Spiral Frequency Selective Surface in a Multilayer Structure

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tian Liu ◽  
Sung-Soo Kim
Keyword(s):  
Reflection Loss ◽  
Multilayer Structure ◽  
Low Frequency ◽  
Optimization Procedure ◽  
Test Sample ◽  
Frequency Selective Surface ◽  
Total Thickness ◽  
Wide Bandwidth ◽  
Frequency Resonance ◽  
Frequency Selective

Abstract A high-capacitive frequency selective surface (FSS) with a new structure of folded spiral conductors is proposed as the small-array periodicity and low-frequency resonance FSS for ultra-wide bandwidth absorbers in a multilayer structure. Due to the folded structure with long effective segments and a small gap, a large value of capacitance for the lowest resonating frequency is obtained. Through a combination of the high-capacitive spiral FSS with other conventional FSSs (square loop, square patch) with a medium- and high-frequency resonance, an ultra-wide absorption bandwidth (4.7–50.0 GHz for −10 dB reflection loss) is designed with a small total thickness of 7.0 mm, which is close to the theoretical limit (6.7 mm). Admittance analysis is conducted for better insight into the optimization procedure. The free space measurement with a test sample prepared by the screen printing method also demonstrates a wide-bandwidth absorption result (5.2–44.0 GHz for −10 dB reflection loss, total thickness = 6.5 mm), which is in good agreement with the simulation result. In addition, the angular stability of the proposed wide-bandwidth absorber is discussed for both TE and TM polarizations in association with unit cell periodicity and grating lobes.

Frequency Selective Surface for Infrared Transmission Suppression at Atmospheric Window

2018 ◽  
Vol 937 ◽  
pp. 89-95
Author(s):  
Xiao Li Chen ◽  
Chang Hui Tian ◽  
Zhi Xin Che
Keyword(s):  
Electromagnetic Waves ◽  
Far Infrared ◽  
Black Body ◽  
Frequency Selective Surface ◽  
Infrared Transmission ◽  
Infrared Band ◽  
Infrared Transmittance ◽  
Wide Range ◽  
Potential Applications ◽  
Frequency Selective

A double screen infrared frequency selective surface (FSS) with dual transmission stopbands was proposed and numerically investigated. Simulation results show that the infrared transmittance of the structure is lower than 10% in mid-infrared band (3~5 μm) and far-infrared band (8 ~14 μm).This structure is polarization insensitive to the incident electromagnetic waves. For a wide range of incident angles from 0° to 60°, the infrared transmittance of the structure is still lower than 25% in the band of interest. Compared with black body, the radiation ratio of structure is lower in the MWIR and LWIR ranges. The structure provide the potential applications for infrared stealth.

Composite Materials Based on Silicone Rubber Used to Mitigation Electromagnetic Pollution

2015 ◽  
Vol 1114 ◽  
pp. 76-80
Author(s):  
Elena Valentina Stoian ◽  
Vasile Bratu ◽  
Florina Violeta Anghelina ◽  
Ileana Nicoleta Popescu
Keyword(s):  
Composite Materials ◽  
Silicone Rubber ◽  
Electromagnetic Waves ◽  
Polymer Matrix Composites ◽  
Raw Materials ◽  
Digital Processing ◽  
Thin Layers ◽  
Matrix Composites ◽  
High Attenuation ◽  
Electromagnetic Pollution

Rapid developments in telecommunications and digital processing of information are facing the problem of electromagnetic wave pollution and interference. The aim of this article is the characterization at microwave frequencies of composite materials based on silicone rubber. These materials contain 80% siloxane rubber and only 20% powdery feeling like nanocarbon and pyrite cinder. To achieve these objectives were reviewed and selected raw materials and characteristics were determined in a structural material, the electromagnetic attenuation as well as electrically, by making measurements of electrical conductivity of thin layers of polymer matrix composites produced by the doctor blade technique. Starting from sample siloxane rubber, i.e. without additives or filler reinforcement in compression analysis we find that reinforcing agents leads to increased values of the modulus of elasticity in especially for pyrite ashes. For materials analyzed in this paper, measurements were made in the frequency range between (1-18) GHz and have found high attenuation over 45 dB in the case of composite materials with pyrite ash filler. So we can say that this materials can used for shielding against electromagnetic waves in order to protect the human factor. The novelty of the paper consists in the compositions of the specimens and their mechanical and electromagnetic characteristics.

Polymer matrix composites and technology

2011 ◽  
Author(s):  
Ru-Min Wang ◽  
Shui-Rong Zheng ◽  
Ya-Ping Zheng
Keyword(s):  
Polymer Matrix ◽  
Polymer Matrix Composites ◽  
Matrix Composites
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