A bi-directional dual-bandwidth microwave absorber for applications in X and Ku bands

2019 ◽  
Vol 11 (9) ◽  
pp. 983-987
Author(s):  
Gobinda Sen ◽  
Santanu Das
Keyword(s):  
Electromagnetic Wave ◽  
Incident Angle ◽  
Microwave Absorber ◽  
Wave Incident ◽  
Absorption Bandwidth ◽  
Radar Absorbing Material ◽  
Ring Shape ◽  
Band Absorption ◽  
Dual Bandwidth ◽  
5 Ghz

AbstractThis paper presents a microwave absorber with dual absorption bandwidth response based upon the direction of electromagnetic wave incident on the surface. The design unit cell comprises a staircase shape metallic patch on the top plane and an array of 2×2 meander square ring shape dual layer frequency selective surfaces (FSS) in the middle and bottom planes. The relative absorption bandwidth (RAB) of 39.40% (5 GHz) with more than 90% absorption of incident wave power is achieved when an electromagnetic wave impinges normally on the top plane making it suitable for wideband applications in the X and Ku bands. For the wave incident normally on the bottom plane, the same structure gives narrow band absorption with an RAB of 2.29% (260 MHz) for more than 90% absorption around 11 GHz. Thus, this bi-directional ability of the proposed design is found to be suitable for radar absorbing material, multi-bandwidth, and diverse applications. The absorption performance is also studied for different values of incident angle. The distribution of surface currents on the staircase patch and on the two FSS layers at resonant frequencies of 11 GHz and 14 GHz is analyzed to elaborate the absorption phenomenon physically. The prototype of this design is fabricated and the experimental results are found to be closely following the simulated one.

scholarly journals One-step hydrothermal synthesis of Ni–Fe–P/graphene nanosheet composites with excellent electromagnetic wave absorption properties

RSC Advances ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 5570-5581 ◽  
Author(s):  
Shuo Zhao ◽  
Chunyu Wang ◽  
Ting Su ◽  
Bo Zhong
Keyword(s):  
Electromagnetic Wave ◽  
Excellent Performance ◽  
Absorption Properties ◽  
Graphene Nanosheet ◽  
Absorption Bandwidth ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
One Step ◽  
5 Ghz ◽  
Minimum Reflection Loss

Ni–Fe–P nanoparticle/graphene nanosheet composites synthesized by a one-step hydrothermal method have excellent performance in the field of electromagnetic wave absorption, with a minimum reflection loss of −50.5 dB and a maximum effective absorption bandwidth of 5 GHz.

Electromagnetic Properties of Bearing Cement-Based Materials

2011 ◽  
Vol 261-263 ◽  
pp. 663-668
Author(s):  
Ai Li Guo ◽  
Ri Gao ◽  
Heng Jing Ba
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Building Materials ◽  
Incident Angle ◽  
High Strength ◽  
Wave Incident ◽  
Electromagnetic Properties ◽  
Frequency Range ◽  
Electromagnetic Wave Incident ◽  
Cement Based Materials

For studying absorption/bearing integration of building materials, high-strength cement-based materials were prepared by using active fly ash, silica fume and quartz, etc. Electromagnetic parameters of the cement-based materials were measured through coaxial method, and then by means of these parameters, the reflectivity of electromagnetic waves of the cement-based materials were simulated under variable electromagnetic wave incident angle (θ), frequency (f) and thickness of the material(d).The reflectivity of electromagnetic waves with 8~18GHz frequency range vertically transmitting into the cement-based materials was obtained through far field radar scattered cross-section measurement, and was compared with simulated reflectance under the same incident conditions. The results show that the high-strength cement-based materials with imaginary part of dielectric constant can consume energy of the incident electromagnetic wave. Incident angle less than 15° has little effect on the reflectivity of the cement-based materials in 2~18GHz frequency range. While the thickness of the cement-based materials is 15mm or 25mm, simulation results of the reflectivity are in good agreement with measured ones. Measured absorption peak and -10dB bandwidth increase with the increasing of thickness of the cement-based materials with compressive strength of 120.7MPa. This suggests that the cement-based materials studied in this paper have the characteristics of absorption/bearing integration.

Microwave wide band absorption by carbon from Corn cob-1

2016 ◽  
Vol 12 (2) ◽  
pp. 4204-4212 ◽  
Author(s):  
Maheshwar Sharon ◽  
Ritesh Vishwakarma ◽  
Abhijeet Rajendra Phatak ◽  
Golap Kalita ◽  
Nallin Sharma ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Agricultural Waste ◽  
Wide Band ◽  
Nickel Nitrate ◽  
Equivalent Amount ◽  
Frequency Range ◽  
Corn Cob ◽  
Different Temperatures ◽  
Band Absorption ◽  
5 Ghz

Corn cob, an agricultural waste, is paralyzed at different temperatures (700oC, 800oC and 900oC). Microwave absorption of carbon in the frequency range of 2 GHz to 8 GHz is reported. Carbon activated  with 5%  nickel nitrate showed more than 90% absorption of microwave in the frequency range from 6 GHz to 8 GHz, while carbon activated  with 10% Nickel nitrate treated corn cob showed 90% absorption  in the frequency range of 2.5 GHz to 5 GHz. Carbon showing the best absorption are characterized by XRD, Raman spectra and SEM . It is suggested that corn cob treatment   alone with KOH did not improve the microwave absorption, whereas treatment along with nickel nitrate improved the absorption property much better. It is proposed that treatment with nickel nitrate helps in creating suitable pores in carbon   which improved the absorption behavior because while treating carbon with 1N HCl helps to leach out nickel creating equivalent amount of pores in the carbon.

scholarly journals Combined Mie Resonance Metasurface for Wideband Terahertz Absorber

2018 ◽  
Vol 8 (9) ◽  
pp. 1679
Author(s):  
Jie Hu ◽  
Tingting Lang ◽  
Changyu Shen ◽  
Liyang Shao
Keyword(s):  
Electric Fields ◽  
Incident Angle ◽  
Absorption Frequency ◽  
Variable Parameters ◽  
Absorption Bandwidth ◽  
Terahertz Absorber ◽  
Mie Resonance ◽  
Traditional Design ◽  
Single Block ◽  
Application Fields

In this paper, we propose a combined metasurface consisting of an aluminum substrate and an array of TiO2 blocks to achieve a wideband terahertz absorber. We incorporated several similar dielectric blocks with different side length into each unit cell. Each dielectric block could cause magnetic-resonance-inducing absorption effect with different peak wavelengths. Thus, our combined metasurface could achieve wider absorption frequency band than the traditional design when these dielectric blocks were properly designed. The absorption bandwidth could be widened nearly 2.5 times and 5 times compared to a single block case when there were four and nine blocks, respectively, andcouldbe further improved by increasing the number of combinations in structures (variable parameters included number, spacing, dimensions etc.). For both TE00 (the electric fields of the light polarized along the y-axis) and TM00 (the electric fields of the light polarized along the x-axis) polarization states, the absorption bandwidth could be widened effectively; even when the incident angle was 45°, the absorption rate could still reach about 75%. This structure is simple and easy to fabricate, and this design concept can also be used in various other application fields.

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