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Your search keyword '"Zhang, Zhi-Ya"' showing total 119 results
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119 results on '"Zhang, Zhi-Ya"'

6. Planar Two-Dimensional Scanning Multibeam Array Antenna Based on a 3 × 3 Butler Matrix Network.

Author

Zhao, Shu-Kuan, Lv, Miao, Zhang, Zhi-ya, Chen, Qiang, and Fu, Guang

Abstract

In this letter, a wideband two-dimensional (2-D) scanning multibeam array antenna is proposed using a novel beamforming network (BFN). First, a novel three-beam Butler matrix (BM) network, as the core of the BFN, is proposed and described. The BM network comprises a directional coupler, T-shaped power dividers, and coupling baluns, which avoids using crossovers and lossy lumped elements as in a conventional BM network. In addition, a dual-stripline structure is employed to combine multiple components, which considerably reduces the BM network aperture. Then, six three-beam BMs are stacked and interconnected to form a complete 2-D BFN, whose scanning features of two orthogonal planes are controlled by two sets of BMs. Finally, to verify the working principle of the BFN, a 3 × 3 all-metal antenna array is designed and combined with the BFN. Notably, the low-profile antenna element achieves a wide operating bandwidth of 34.5%. Furthermore, a prototype is fabricated and tested, which shows that the antenna realizes switched beams in nine directions, indicating that an excellent 2-D scanning function is realized. [ABSTRACT FROM AUTHOR]

Published
2022
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26. Vacuum Ultraviolet Excited Photoluminescence Properties of Novel Na 3 Y 9 O 3 (BO 3 ) 8 :Tb 3+ Phosphor

Author

Zhang Zhi-Ya, Wang Yuhua, Jiang Yan-Ping, Xie Peng, LI Huihui, and Zhang Jiachi

Subjects
Materials science, Photoluminescence, Quenching (fluorescence), business.industry, Analytical chemistry, General Physics and Astronomy, Phosphor, Spectral line, Absorption band, Excited state, Optoelectronics, business, Absorption (electromagnetic radiation), Luminescence
Abstract

The novel vacuum ultraviolet (VUV) excited Na3Y9O3(BO3)8:Tb3+ (NYOB:Tb3+) green phosphor is prepared. Strong VUV photoluminescence and high quenching concentration of Tb3+ (20 wt%) are observed in NYOB:Tb3+ and the strong emission are correlated with the unique layer-type structure of NYOB. All the characteristic 4f-5d transitions of Tb3+ and the host absorption band in VUV region are identified in the excitation spectrum. Based on the results, the energy levels scheme of Tb3+ in NYOB:Tb3+ is first established. This newly developed NYOB:Tb3+ phosphor shows excellent optical properties when compared with the commercial Zn2SiO4:Mn2+ and would be a potential VUV-excited green phosphor.

Published
2008

34. Design of multi‐beam antenna based on Rotman lens.

Author

Zhang, Zhi‐Ya, Zhao, Yarui, Ji, Luyang, Zuo, Shao‐Li, Xu, Feifei, and Fu, Guang

Subjects
*ANTENNAS (Electronics), *BROADBAND communication systems, *YAGI antennas, *ANTENNA arrays, *LASER beams
Abstract

Abstract: A planar Rotman lens antenna that generates multiple beams is presented over a wide angular range. The proposed multi‐beam antenna consists of a Rotman lens and a ten‐element printed Yagi antenna array. By properly comparing optical aberrations, expressing as the normalized path length errors Δl, the suitable ratio of on‐axis to off‐axis focal length (g = G/F) is acquired so as to minimize phase errors for the array elements. Ten dummy ports are employed to reduce the performance deterioration caused by energy reflection. A prototype with seven input ports was fabricated and measured, covering a wide scanning angle of 60° (–30°, 30°). The measured beam patterns show that the seven beam gains are distributed from 11.9 to 13.6 dBi under operating of 8.15 GHz. Both the simulated and measured results are used to verify the design approach. [ABSTRACT FROM AUTHOR]

Published
2018
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35. A wideband circularly polarized antenna using mutual coupling method.

Author

Yang, Long, Zhao, Chunliu, Chen, Xi, Zhang, Zhi‐Ya, Fu, Guang, and Yan, Zehong

Subjects
BROADBAND communication systems, ANTENNAS (Electronics), ANTENNA arrays, BANDWIDTHS, IMPEDANCE matching, PHASE shifters, POWER dividers
Abstract

A novel wideband circularly polarized (CP) antenna is presented in this article. The proposed antenna consists of a four-leaf clover patch, four L-probes, and wideband networks. Based on the tightly coupled mechanism, the four L-probes are formed as a ring with the adjacent ones kept close for strong mutual coupling. Consequently, the proposed antenna realizes a wideband impedance matching. Meanwhile, the four-leaf clover patch is put closely inside of the ring for further improving the impedance bandwidth, which is proximity-coupled fed by the four sequential-rotation L-probes with phase of 0°, 90°, 180°, and 270°. The four L-probes are connected to the respective ports of a wideband feeding network by a two-stage impedance transforming network. The measured results indicate that the proposed design has an impedance bandwidth of 66.7% from 1.0 to 2.0 GHz for VSWR ≤ 2 and a 3-dB axial ratio bandwidth of 56.5% from 1.08 to 1.93 GHz. Furthermore, in the operating bandwidth, stable and symmetry radiation patterns and high gain are obtained. The design has a 3-dB gain bandwidth of 38% from 1.3 to 1.9 GHz with a peak gain of 8.5 dBic. [ABSTRACT FROM AUTHOR]

Published
2018
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