Basic Characteristics of the Single Layer Type Microwave Absorber in X Band Using Superconductor Powder

2006 ◽  
Vol 47 ◽  
pp. 93-97
Author(s):  
Katsuyoshi Hotta ◽  
Hiroyuki Shimizu ◽  
Y. Watanabe ◽  
Haruo Hirose
Keyword(s):  
Reflection Loss ◽  
Short Circuit ◽  
Single Layer ◽  
Liquid Nitrogen Temperature ◽  
Microwave Absorber ◽  
Complex Permeability ◽  
Theoretical Formula ◽  
X Band ◽  
Guide System ◽  
Basic Characteristics

The purpose of this study is to examine the basic characteristics of the single layer type microwave absorber in X band. Samples were produced from Bi system (2223) superconductor powder and metallic powder and inserted into a wave guide system where the complex reflection intensity was measured (The short circuit method) by using the vector network analyzer[1]. As the result, at the room temperature (300K), the reflection loss is apt to increase with increasing the content of the Bi system superconductor powder. Furthermore, the measured value of the reflection loss agreed with the value calculated from the complex permittivity εr* . At liquid nitrogen temperature (77K) where the superconductor powders are in the superconducting state, some differences occurred between the calculated value and the measured one of the reflection loss. For the metallic powders, copper powder showed good agreement between the calculated and the measured of reflection loss. For the magnetic material, it was concluded that the theoretical formula under consideration of complex permeability μr* should be derivated.

scholarly journals Preparation and Thickness Optimization of Graphenic-Based Carbon Material as a Microwave Absorber

2022 ◽  
Vol 19 (1) ◽  
pp. 1714
Author(s):  
Affandi Faisal Kurniawan ◽  
Mohammad Syaiful Anwar ◽  
Khoirotun Nadiyyah ◽  
Yana Taryana ◽  
Muhammad Mahyiddin Ramli ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Layer Thickness ◽  
Reflection Loss ◽  
Morphological Structure ◽  
Single Layer ◽  
Functional Materials ◽  
Microwave Absorber ◽  
Coconut Shell ◽  
Complex Permeability ◽  
Carbon Compounds

The purpose of this study is to optimize the thickness of a layered graphenic-based carbon compound, which is a non-magnetic material derived from biomass (old coconut shell). After the sample was exfoliated using HCl solution, the morphological structure showed that the material used in this study is a reduced graphene oxide (rGO), similar to carbon but with a thickness of less than 10 nm and lateral size in submicron (100 nm). The sample with a 2 mm thickness was then characterized using a vector network analyzer (VNA) to measure its reflection loss (RL). The measurement result is evaluated by converting the S-parameter values (S11 and S21) from the VNA using the Nicolsson Ross Weir (NRW) method to obtain input variables such as relative complex permeability and relative complex permittivity. Following this, the single-layer thickness of the sample was optimized using a genetic algorithm (GA), which can predict the appropriate thickness so that the optimum RL can be obtained. The optimum thickness of the sample was found to be 3.48 mm, which resulted in a much higher RL. The RL was re-measured for verification using a sample with the corresponding optimized thickness, revealing that this optimization is feasibly operational for a radar absorbing material (RAM) design. HIGHLIGHTS Carbon compounds containing graphenic phase derived from coconut shell are functional materials having various unique properties such as superior electrical conductivity, large surface area, and excellent structural flexibility, and microwave absorbtion The single-layer microwave absorber employing carbon compounds has been prepared The layer thickness optimized using a genetic algorithm (GA) can estimate the appropriate design with the maximum reflection loss (RL)

scholarly journals Microwave Absorption Performance of Single-Layer and Multi-Layer Structures Prepared by CNTs/Fe3O4 Nonwoven Materials

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1000
Author(s):  
Rong Zhan ◽  
Jiaqiao Zhang ◽  
Qiang Gao ◽  
Qi Jia ◽  
Zhixiang Zhang ◽  
...  
Keyword(s):  
Reflection Loss ◽  
Single Layer ◽  
Frequency Range ◽  
Band Frequency ◽  
Layer Structures ◽  
X Band ◽  
Combination Scheme ◽  
Film Forming ◽  
Hot Rolled ◽  
Minimum Reflection Loss

Electromagnetic radiation can cause serious harm to the human body, such as the rise in body temperature and the decrease in immune function. In this study, the carbon nanotubes (CNTs)/Fe3O4 nonwovens were used to prepare wearable flexible absorbing materials. First, the single-layer absorbing structures were prepared by hot rolling, dipping, and film fabrication, respectively. Then, the single-layer structures were combined to form the multi-layer absorbing structures. By testing and analyzing the absorbing performance of various structures in the X-band frequency range, the optimum combination scheme was found, together with a good reflection loss value of CNTs/Fe3O4 nonwoven material. The experiment results displayed that the single-layer hot-rolled nonwovens modified by CNTs have the best wave absorbing performance. Its minimum reflection loss of −18.59 dB occurred at 10.55 GHz, and the efficient frequency occurred at 8.86–12.40 GHz. The modified film can significantly improve the absorbing performance of multi-layer structures. In addition, the absorbing performance was closely related to both the place where the absorbing film was introduced and the type of absorbing fillers. When the film-forming CNTs (FC) film was located at the bottom layer of the multi-layer structure, the hot rolled CNTs hot rolled mixed reagent film forming CNTs (HC-HM-FC) structure constructed exhibited the best absorbing effects. Its minimum reflection loss can reach −33 dB, and the effective absorbing frequency range covered half of the X-band.

Double Layer Microwave Absorption Characteristics of Barium Hexaferrite/Silica Composite for X-Band Frequencies

2018 ◽  
Vol 929 ◽  
pp. 109-115 ◽  
Author(s):  
Erfan Handoko ◽  
Iwan Sugihartono ◽  
Mangasi Alion Marpaung ◽  
Maulana Randa ◽  
Mudrik Alaydrus ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Double Layer ◽  
Reflection Loss ◽  
Barium Hexaferrite ◽  
Complex Permeability ◽  
X Ray Diffraction ◽  
Silica Composite ◽  
X Band ◽  
Line Theory ◽  
Absorption Characteristics

Microwave absorption characteristics of double layer of barium hexaferrite attached on the silica to from a composite on the basis of wave propagation theory have been investigated. Barium hexaferrite, BaFe12O19, was synthesized through ceramic method from stoichiometric mixtures of BaCO3 and Fe2O3 as precursors. The mixture was pelletized under the pressure of 10 MPa and sintered at 1100 °C for 5 hours. Silica in the forms of powder was purified by using HCl. The crystal structure of the samples was characterized using X-ray diffraction (XRD), microstructure was examined using scanning electron microscope (SEM), hysteresis curves recorded by PERMAGRAPH techniques, whereas the microwave absorbing properties for X-band was recorded using a vector network analyzer (VNA). Relative complex permeability and permittivity, and reflection loss values were calculated at given thickness according to transmittance line theory within the range 8.2–12.4 GHz. Based on this study, the layer dimension and frequency that results in low reflection loss can be estimated from the material properties of the barium hexaferrite/silica composite material.

Investigation on AR Techniques of Silicon Solar Cells

2014 ◽  
Vol 521 ◽  
pp. 52-55
Author(s):  
Chun Rong Xue ◽  
Yu Qin Gu ◽  
Ming Liang Deng
Keyword(s):  
Solar Cells ◽  
Reflection Loss ◽  
Short Circuit ◽  
Surface Texturing ◽  
Single Layer ◽  
Short Circuit Current ◽  
Silicon Solar Cells ◽  
Textured Surface ◽  
Antireflection Coatings ◽  
Si Solar Cells

This work presents study of both the antireflection coatings on silicon solar cells and surface texture of silicon solar cell, with the aim to prepare high quality Si solar cells. Surface texturing, either in combination with an anti-reflection coating or by itself, can be used to minimize reflection, but the large reflection loss can be reduced significantly via a suitable anti-reflecting coatings. Significant improvement of the short circuit current after anti-reflecting coatings was observed. It is found that the currentvoltage characteristic with a double-layer anti-reflecting coatings is better than that with a single-layer anti-reflecting coatings. Depositing a multilayer on the textured surface reduces the large reflection loss significantly. The short circuit current of silicon solar cells has significant improvement after depositing anti-reflecting coatings on textured surface silicon, and it increases the efficiency of the Si solar cells.

scholarly journals Effect of different permeability on electromagnetic properties of absorbing materials

2018 ◽  
Vol 197 ◽  
pp. 02015 ◽  
Author(s):  
Riser Fahdiran ◽  
Yuliyanti Dwi Utami ◽  
Erfan Handoko
Keyword(s):  
Transmission Line ◽  
Reflection Loss ◽  
Single Layer ◽  
Electromagnetic Properties ◽  
Complex Permeability ◽  
Transmission Line Theory ◽  
Microwave Frequencies ◽  
Microwave Absorbing Properties ◽  
Absorbing Materials ◽  
Line Theory

In this study, we have simulated and investigated electromagnetic properties of six types materials using a single layer metal backed absorber model that were determined at microwave frequencies 8.2 up to12.4 GHz. The reflection loss was simulated for different thicknesses in the range of 0.85 to 1.05 mm based on the relative complex permeability and permittivity referring to transmission line theory. The optimal microwave absorbing properties was be resulted by A3 sample. The minimum RL of −23.84 dB can be obtained at 10.72 GHz with thin thickness of 0.95 mm. This method paves a new avenue to design magnetic and dielectric absorbing materials.

scholarly journals Reflection Loss Properties of Microwave Absorber using Bi-System Superconductor at X-Band

2005 ◽  
Vol 52 (12) ◽  
pp. 923-927 ◽  
Author(s):  
Katsuyoshi Hotta ◽  
Hayato Imaizumi ◽  
Kouichi Sasaki ◽  
Yasuo Watanabe ◽  
Haruo Hirose
Keyword(s):  
Reflection Loss ◽  
Microwave Absorber ◽  
X Band
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