scholarly journals Wave Absorption Control of Rope System by Using Impedance Matching Condition

2005 ◽  
Vol 71 (703) ◽  
pp. 845-851 ◽  
Author(s):  
Muneharu SAIGO ◽  
Nobuo TANAKA ◽  
Kiyoshi TAKAGI
Keyword(s):  
Impedance Matching ◽  
Matching Condition ◽  
Wave Absorption ◽  
Absorption Control ◽  
Rope System

scholarly journals Electromagnetic Wave Absorption of Periodic Cylindrical Structured Gypsum Composites Incorporate With Different Carbonaceous Materials

2021 ◽  
Author(s):  
Shuai Xie ◽  
Yuan Zhang ◽  
Zhijiang Ji ◽  
Jing Wang
Keyword(s):  
Wave Attenuation ◽  
Impedance Matching ◽  
Matching Condition ◽  
Destructive Interference ◽  
Carbonaceous Materials ◽  
Moulding Process ◽  
Wave Absorption ◽  
Absorbing Materials ◽  
Absorption Performance ◽  
Em Field

Abstract In order to improve the impedance matching condition and broaden the effective absorbing bandwidth, a series of cylindrical periodic structured gypsum composites with different kinds of carbonaceous materials as absorbents were fabricated by two-step moulding process. The influences of the mass fraction of helical carbon fiber (HCF), carbon nanotube (CNT), and graphene (GE) on the morphology, permittivity, resistivity, and electromagnetic (EM) wave absorbing properties of the proposed gypsum composites were investigated. The experimental results show that the composite with 2 wt.% HCF exhibits optimum EM wave absorption performance, its reflection loss is lower than -10 dB in 2-18 GHz and bandwidth thickness ratio coefficient reaches 0.8 GHz/mm. The EM wave absorption mechanisms were further explained by the simulation of EM field and power loss distribution. The dielectric loss of carbonaceous absorbents, the destructive interference, and the EM wave diffraction and multiple refractions caused by the periodic cylindrical arrays are the main EM wave attenuation mechanisms of the fabricated composites. This study could provide guidance for the design of broadband EM wave absorbing materials.

scholarly journals Facile Synthesis of Cobalt-Doped Porous Composites with Amorphous Carbon/Zn Shell for High-Performance Microwave Absorption

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 330 ◽  
Author(s):  
Qilei Wu ◽  
Huihui Jin ◽  
Bin Zhang ◽  
Siqi Huo ◽  
Shuang Yang ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Amorphous Carbon ◽  
Porous Carbon ◽  
High Performance ◽  
Impedance Matching ◽  
Broad Band ◽  
Matching Condition ◽  
Carbon Composite ◽  
Absorption Capacity ◽  
Zeolitic Imidazolate Framework

A facile method for the preparation of microwave absorbers with low density, high microwave absorptivity, and broad band is of paramount importance to the progress in practical application. Herein, commonly-used metal organic frameworks (MOFs) prepared just by mechanical stirring in methanol at room temperature were chosen as sacrificial templates to synthesize porous carbon composites with tunable dielectric and magnetic properties. With the replacement of Co atoms on the surface of zeolitic imidazolate framework-67 (ZIF-67) by Zn atoms, a Co-doped porous carbon composite with a low-dielectric amorphous carbon/Zn shell was constructed after annealing, leading to excellent impedance matching condition. Consequently, the as-obtained composite (Co/C@C-800) shows marvelous microwave absorption properties with an absorption capacity of −43.97 dB and a corresponding effective absorption bandwidth of 4.1 GHz, far exceeding that of the traditional porous carbon and composites directly derived from ZIF-67. The results provide a convenient way to modify MOFs for enhanced microwave absorption materials from the synergy of dielectric and magnetic losses.

scholarly journals Bandwidth Enhancement Technique of the Meandered Monopole Antenna

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Chien-Jen Wang ◽  
Dai-Heng Hsieh
Keyword(s):  
Communication Systems ◽  
Coplanar Waveguide ◽  
Impedance Matching ◽  
Ground Plane ◽  
Matching Condition ◽  
Resonant Mode ◽  
Monopole Antenna ◽  
Dual Band ◽  
Impedance Bandwidth ◽  
Feeding Structure

A small dual-band monopole antenna with coplanar waveguide (CPW) feeding structure is presented in this paper. The antenna is composed of a meandered monopole, an extended conductor tail, and an asymmetrical ground plane. Tuning geometrical structure of the ground plane excites an additional resonant frequency band and thus enhances the impedance bandwidth of the meandered monopole antenna. Unlike the conventional monopole antenna, the new resonant mode is excited by a slot trace of the CPW transmission line. The radiation performance of the slot mode is as similar as that of the monopole. The parametrical effect of the size of the one-side ground plane on impedance matching condition has been derived by the simulation. The measured impedance bandwidths, which are defined by the reflection coefficient of −6 dB, are 186 MHz (863–1049 MHz, 19.4%) at the lower resonant band and 1320 MHz (1490–2810 MHz, 61.3%) at the upper band. From the results of the reflection coefficients of the proposed monopole antenna, the operated bandwidths of the commercial wireless communication systems, such as GSM 900, DCS, IMT-2000, UMTS, WLAN, LTE 2300, and LTE 2500, are covered for uses.

scholarly journals Comparative Study of Microstrip Patch Antenna for Different Feed Line and Different Substrate

2020 ◽  
pp. 462-469
Author(s):  
Harish Langar ◽  
Atul Shire
Keyword(s):  
Patch Antenna ◽  
Impedance Matching ◽  
Matching Condition ◽  
Microstrip Patch Antenna ◽  
Design Parameters ◽  
Feed Line ◽  
Microstrip Patch ◽  
Feeding Technique ◽  
Design Software ◽  
Feeding Techniques

This paper describes different feeding technique and different substrate applicable to Microstrip patch antenna which is one of the important aspects. A good impedance matching condition between the line and patch without any additional matching elements depends on feeding techniques used and substrate used. After analysis various feeding techniques for different substrate, this paper gives a better understanding of the design parameters of an antenna and their effect on Impedance, VSWR, bandwidth and gain. Finally, simulation is done using design software HFSS.

Fe3O4-decorated single-walled carbon nanohorns with extraordinary microwave absorption property

RSC Advances ◽  
2015 ◽  
Vol 5 (92) ◽  
pp. 75817-75822 ◽  
Author(s):  
Longbin Cui ◽  
Yang Liu ◽  
Xiaohui Wu ◽  
Ziqi Hu ◽  
Zujin Shi ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Microwave Absorption ◽  
High Dielectric Constant ◽  
Impedance Matching ◽  
Microwave Absorption Property ◽  
Absorption Property ◽  
Carbon Nanohorns ◽  
Single Walled Carbon ◽  
Wave Absorption ◽  
High Dielectric

Single-walled carbon nanohorns (SWCNHs) are seldom used as electromagnetic (EM) wave absorption materials due to their inferior impedance matching resulting from their high dielectric constant.

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