scholarly journals Design of An Ultra-Thin and Broadband Absorption Materials For Middle-Temperature Applications

2021 ◽  
Author(s):  
Yanmin Jia ◽  
Zhaoning Yang ◽  
Lu Gao ◽  
Wei Ren ◽  
Ruiduan Zhang ◽  
...  
Keyword(s):  
Reflection Loss ◽  
Frequency Selective Surface ◽  
Complex Permeability ◽  
Frequency Range ◽  
Broadband Absorption ◽  
Radar Absorbing Material ◽  
Temperature Environment ◽  
Absorbing Material ◽  
Relationship Of ◽  
The Relationship

Abstract A radar absorbing material (RAM) is designed based on the magnetic ceramic and frequency selective surface (FSS). The phase composition and micromorphology were characterized, respectively. The complex permittivity and complex permeability of magnetic ceramic were tested and studied from 25 ℃ to 500 ℃ temperature. Based on the experimental and simulation results, the changes of reflection loss along with the structure parameters of RAM are analyzed at 500 ℃. The relationship of reflection loss varies with temperature are studied. The analytical results show that the absorption property of the RAM increases with the increase of temperature. An optimal absorption of RAM is obtained at 500℃. When the thickness of RAM is 1.5 mm, the reflection loss lower than -10 dB can be obtained in the frequency range from 8.2 ~ 16 GHz. More than 90% microwave energy can be consumed in the RAM which may be applied in the high temperature environment.

The Noise Characteristics Research in Subway Cars

2014 ◽  
Vol 1051 ◽  
pp. 431-434
Author(s):  
Jian Hui Tian ◽  
Lian Jian ◽  
Bing Li
Keyword(s):  
Real Time ◽  
High Frequency ◽  
Noise Spectrum ◽  
Frequency Range ◽  
Noise Characteristics ◽  
Spectrum Distribution ◽  
Spectrum Characteristics ◽  
Relationship Of ◽  
The Relationship

The noise of different points in four sections of Shenzhen subway was tested by this paper. Real-time SPL and noise spectrum distribution curves at bogie were given, while the equivalent SPL curve was also shown. The relationship of subway speed and noise SPL was investigated. The regular of noise spectrum characteristics and SPL was obtained. The results show that the noise SPL increases with the increase of the speed. Looking from the frequency range, the frequency corresponding to larger noise SPL amplitude mainly concentrates in the lower frequency while the subway stopping, the frequency corresponding to larger noise SPL amplitude mainly concentrates in high frequency while the subway running.

Self-Actualization as Related to Frequency, Range, and Pattern of Religious Experience

1979 ◽  
Vol 7 (1) ◽  
pp. 39-47 ◽  
Author(s):  
John A. Larsen
Keyword(s):  
Religious Experience ◽  
Personal Data ◽  
Religious Experiences ◽  
Frequency Range ◽  
Validity And Reliability ◽  
Personal Orientation Inventory ◽  
Self Actualization ◽  
Personal Orientation ◽  
Relationship Of ◽  
The Relationship

This study investigated the relationship of frequency, range, and pattern of religious experience to self-actualization. The Religious Experience Measure (REM), a paper and pencil instrument, was constructed to provide measures of Stark's confirming, responsive, ecstatic, and revelational experiences. Validity and reliability studies yielded favorable results. In a classroom setting, the 401 undergraduates who comprised the sample were administered the Personal Data Sheet (PDS), the Personal Orientation Inventory (POI), and the REM. Results showed that high and low self-actualizers alike have religious experiences and that such experiences cannot inherently be viewed as either symptoms of pathology or evidence of positive mental health. However, frequency, range, and pattern are dimensional aspects of religious experience which are differentially related to self-actualization.

Effect of Filler Concentration and Time Sonication of ZnO Composite for Radar Absorbing Material Applications

2021 ◽  
Vol 1028 ◽  
pp. 249-254
Author(s):  
Yus Rama Denny ◽  
Adhitya Trenggono ◽  
Teguh Firmansyah ◽  
Irvan Revaldi ◽  
Yana Taryana ◽  
...  
Keyword(s):  
Reflection Loss ◽  
Hexagonal Structure ◽  
Filler Concentration ◽  
Sonication Time ◽  
X Ray Diffraction ◽  
Radar Absorbing Material ◽  
Structure Morphology ◽  
Absorbing Material ◽  
Mixing Method ◽  
Absorption Percentage

Effects of filler concentration and sonication time on the structure, morphology, reflection loss and absorption percentage of ZnO composite was investigated. The structure, morphology, reflection loss and absorption percentage of the composite was investigated using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vector Network Analyzer (VNA). The ZnO composite was made by solution mixing method with the epoxy resin as a filler varied of 10 wt%, 20 wt%, and 30 wt%. The hardener was mixed to the ZnO composite by the composition of 2: 1. The sonication time was varied of 30, 45 and 60 minutes. The XRD showed that the crystal structure of ZnO composite was confirmed as a hexagonal structure and the structure was not change for all composite. The VNA results showed that the optimum reflection loss value was-9.37042 dB at the frequency of 12.3 GHz for the filler composition of 20 wt% and sonification time of 45 minutes. On the other hand, the minimum reflection loss value was-6.86845 dB at the frequency of 12.3 GHz for the filler composition of 10 wt% and sonification time of 45 minutes. In addition, the optimum absorption percentage was 18 % at a filler composition of 10 wt% with 60 minutes sonication time. This study demonstrates a promising method to improve a microwave absorption of ZnO composites.

Microwave Absorbing Property of Thin Coating in the Broadband Low-Frequency Range

2018 ◽  
Vol 916 ◽  
pp. 33-37
Author(s):  
Le Chen ◽  
Zhao Zhan Gu ◽  
Ming Xue Zhang
Keyword(s):  
Reflection Loss ◽  
Complex Permittivity ◽  
Carbonyl Iron ◽  
Low Frequency ◽  
Complex Permeability ◽  
Frequency Range ◽  
Microwave Absorbing ◽  
Absorbing Property ◽  
Lower Frequency Region ◽  
Minimum Reflection Loss

Coatings with flake carbonyl-iron powder as absorber and polyurethane resin as matrix were prepared. The complex permittivity, complex permeability and microwave-absorbing properties were investigated in the frequency range of 2–18 GHz. Both the complex permittivity and permeability of the flaky carbonyl-iron were increased compared to the spherical powders. The minimum reflection loss decreased and the matching frequency shifted to the lower frequency region with increase in the coating thickness. The band width can reach nearly 16GHz as the RL was below than-4 dB with thickness only 1.4 mm. The minimum reflection loss value of-14.5 dB was obtained at 3.56 GHz for the 1.6mm coatings with 89 wt% carbonyl-iron powders. These results showed that the coatings were favorable for the broadband low-frequency microwave absorption with a small thickness.

scholarly journals The Polarization of Type V Bursts

1980 ◽  
Vol 86 ◽  
pp. 333-338 ◽  
Author(s):  
D.E. Gary ◽  
S. Suzuki ◽  
G.A. Dulk
Keyword(s):  
Statistical Study ◽  
The Sun ◽  
Frequency Range ◽  
Type Iii ◽  
Brightness Temperatures ◽  
Type V ◽  
Relationship Of ◽  
The Relationship

From observations with the Culgoora spectropolarimeter operating in the frequency range 24–200 MHz, we find that Type V bursts are often polarized in the opposite sense from the preceding Type III bursts. We present here the results of a statistical study of how frequently this occurs and the relationship of such polarization reversals to the position of the source on the disk of the Sun. We then examine two possible reasons for the reversal of polarization. In a paper published elsewhere (Dulk et al., 1979) we give a more detailed description and include observations of source sizes, positions and brightness temperatures of Type III-V bursts.

A Comparative Study on Process-Properties Correlation of Nano Radar Absorbing Heat Treated Materials

2009 ◽  
Vol 67 ◽  
pp. 39-44 ◽  
Author(s):  
Rahul Sharma ◽  
Ramesh Chandra Agarwala ◽  
Vijaya Agarwala
Keyword(s):  
Reflection Loss ◽  
Ostwald Ripening ◽  
Barium Hexaferrite ◽  
Precipitation Process ◽  
Morphological Transformation ◽  
Radar Absorbing Material ◽  
Quantum Size ◽  
Heat Treated ◽  
Absorbing Material ◽  
Co Precipitation

Single phase M-type barium hexaferrite nano radar absorbing material (NRAM) i.e., BaFe12O19 were synthesized by modified flux method that combines the controlled chemical co-precipitation process for nucleation and complete uniform growth during annealing with NaCl flux under microwave annealing (MWA) and vacuum annealing (VA). Uniform morphological transformation of nano crystals from spherical (~ 10 nm) to prism faces (~ 35 nm) were observed under TEM during annealing. The effect of such systematic nano morphological transformation of NRAM was observed on magnetic and reflection loss (RL) properties. Maximum reflection loss (RL) was improved to 37.15 dB at 16.00 GHz for MWA at 760 watt and 27.56 dB at 15.75 GHz for VA at 1200 oC with continuous increasing absorption range under −10 dB for 2 mm thick coating layer in the Ku Band (12.4-18.0 GHz).. Excellent microwave absorption properties are a consequence of accurate EM match in the nano morphological planes, a strong natural resonance, as well as multipolarization. This process of crystal growth, morphology evolution and RL enhancement with respect to the heat treatments were also explained in terms of Ostwald ripening and quantum size effect.

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