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792 results on '"Huang, Kama"'

61. CPW-fed circularly-polarized antenna array with high front-to-back ratio and low-profile

Author

Liu Yilin and Huang Kama

Subjects
low-profile antenna, coplanar waveguide, cpw–slotline transition, circular polarization, sequential feeding, 41.20.jb, 84.40.ba, Physics, QC1-999
Abstract

A novel design of a coplanar waveguide (CPW) feed antenna array with circular polarization (CP) and a high front-to-back ratio is described. The proposed CP array is achieved by using a compact CPW–slotline transition network etched in the ground plane. The measured results show that this kind of feeding method can improve the impedance bandwidth, as well as the axial ratio bandwidth of the CP antenna array and provide adequate gain. The proposed array can achieve a 6.08% impedance bandwidth and a 4.10% CP bandwidth. Details of the antenna design and experimental results are presented and discussed.

Published
2018
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62. Outside Front Cover: Plasma Process. Polym. 6/2023

Author

Zhao, Chaoxia, primary, Li, Xinxin, additional, Agrawal, Dinesh K., additional, Yan, Zhili, additional, Qi, Siyao, additional, Liu, Yao, additional, Ma, Tianbao, additional, Chen, Qian, additional, Zhang, Yi, additional, Wang, Ce, additional, and Huang, Kama, additional

Published
2023
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63. The Effective Flow Coefficient Design Method of Microwave-Assisted Catalytic Reactor for Gas Treatment

Author

Li, Hao, Huang, Kama, Wang, Yijun, and Dong, Penghao

Abstract

Microwave heating is a promising technology widely used to enhance chemical processes in multiphase catalytic reactions. The design of the microwave reactor is crucial for microwave-assisted multiphase catalysis. However, assessing the reactor design’s impact on catalytic performance is often based on experiments and experience. In this study, we propose a method based on multiphysics simulation to evaluate and guide the design and scale-up of microwave cavities. First, we conduct multiphysics calculations by establishing an enlarged microwave reactor model to obtain the heating situation and gas flow stats on the catalyst support. Subsequently, by integrating parameters such as flow rate, temperature, and effectiveness, we construct the effective flow coefficient (EFC) to characterize and guide the reactor’s design quantitatively. Based on this method, we calculated four reactor models with different internal structures and obtained EFC values of 0.17, 0.19, 0.1, and 0.69, respectively. The results show that this method can quantitatively guide and optimize the reactor design from aspects such as the reactor structure, catalyst support structure, reactant feed configuration, and microwave feed configuration. This study contributes to the promotion of scale-up in microwave-assisted gas–solid catalytic reactors.

Published
2024
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64. A novel on-line microwave diagnostic for an atmospheric pressure air plasma based on an artificial neural network.

Author

Chen, Wenqi, Wu, Li, Zhong, Yu, Yu, Yutian, Zhang, Zhuoyue, and Huang, Kama

Subjects
ATMOSPHERIC pressure plasmas, MICROWAVE plasmas, ATMOSPHERIC pressure, MICROWAVE devices, DRUDE theory, PERMITTIVITY measurement, PERMITTIVITY
Abstract

Permittivity is an important aspect of the design of microwave devices. In order to design microwave devices that are more suitable for the excitation of air plasmas, this paper presents a method for the on-line measurement of the relative permittivity of an atmospheric pressure air plasma with 2.45 GHz microwaves. First, a ridged waveguide is designed and constructed to excite the air. Using the ridged waveguide, the plasma can be excited and measured simultaneously. An artificial neural network trained with simulated data is integrated into the system to invert the dielectric constant of the air plasma being measured. At a power of 786 W and an airflow rate of 1250 L/h, the real and imaginary parts of the permittivity are obtained to be −1244 and 60, respectively. The forecasted errors on the real part and the imaginary part of the relative permittivity are kept at around 5% and 3%. The Drude model is used to construct a relationship between the electronic and dielectric properties. This diagnostic method is simple to operate and has a high degree of generality. It should be useful in the design of microwave plasma devices and can greatly improve the efficiency of microwave plasma equipment. [ABSTRACT FROM AUTHOR]

Published
2023
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72. Mitigating Thermal Focusing in Microwave Heating of Cylindrical Loads by Resonant Rings.

Author

Yang, Fengming, Yan, Xueting, Zhu, Huacheng, Yang, Yang, and Huang, Kama

Subjects
HEATING load, MICROWAVE heating, MICROWAVES, TEMPERATURE distribution
Abstract

Cylindrical loads are commonly found in microwave heating. However, cylindrical loads tend to have a thermal focus, leading to uneven microwave heating. In this paper, a novel microwave heating method was proposed by employing resonant rings to mitigate the thermal focus of cylindrical loads. Firstly, a multiphysics simulation model for microwave heating of a cylindrical tube is established, and the influence of the resonant ring around the cylindrical tube on the temperature distribution of load was analyzed. Subsequently, microwave heating experiments of agar gels with and without resonant rings were carried out. In agreement with the simulation results, the use of resonant rings reduces the coefficient of temperature variation (COV) from 1.064 to 0.793. In addition, the parameters affecting the heating uniformity of the cylindrical tube were discussed through simulations. [ABSTRACT FROM AUTHOR]

Published
2023
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84. Non-diffraction surface wave with controllable deflection angle by using metasurfaces.

Author

Liu, Qian, Lu, Ping, Huang, Kama, and Qian, Daichao

Subjects
REFRACTIVE index, METALLIC surfaces
Abstract

A planar metasurface Bessel lens has been proposed for non-diffraction surface wave deflection, which is composed of a planar flat lens and an asymmetric gradient refractive index lens. According to the desired refractive index distribution of the two lenses, a metasurface, consisting of sub-wavelength metallic square rings of different sizes, is constructed to realize the planar Bessel lens. Through the planar Bessel lens, the cylindrical-like surface wave radiated from a point source is converted to an inclined non-diffraction surface wave. The planar Bessel lens is fabricated, and the measurement results show good agreement with the full-wave simulation results, which would verify the correctness of the proposed theory. [ABSTRACT FROM AUTHOR]

Published
2020
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