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Reconfigurable Compact Wideband Circularly Polarised Dielectric Resonator Antenna for Wireless Applications

Computers, Materials & Continua 2021年第8期68卷 2095-2109页

作者： Shahid Khan Xin Cheng Ren Haider Ali Camel Tanougast Abdul Rauf Safdar Nawaz Khan Marwat Muhammad Rizwan Anjum LCOMS ASECUniversity de LorraineMetz57070France School of Physics and Electronic Information Yanan UniveristyYanan761000China Department of Electronics Technology University of TechnologyNowshera24100Pakistan Department of Electrical Engineering National University of Sciences and TechnologyIslamabad44000Pakistan Department of Computer Systems Engineering University of Engineering and TechnologyPeshawar25120Pakistan Department of Electronic Engineering The Islamia University of BahawalpurBahawalpur63100Pakistan

In this work,a novel compact wideband reconfigurable circularly polarised(CP)dielectric resonator antenna(DRA)is *** L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped *** arrangement of feed-line helps to generate two orthogonal modes inside the DR,which makes the design circularly polarised.A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode *** switches located at the left and right of the micro-strip line helps in performing two switching *** novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless *** the switching operation I,the achieved impedance bandwidth is 24%while axial ratio bandwidth(ARBW)is 42%.For this switching state,the design has 100%CP ***,the switching operation II achieves 60%impedance bandwidth and 58.88%ARBW with 76.36%CP *** proposed design has a maximum measured gain of 3.4 dBi and 93%radiation *** proposed design is novel in terms of compactness and performance *** prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.

关键词： Circularly polarized DRA ARBW bandwidth gain radiation efficiency

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A way of estimating the characteristic slip displacement

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Earthquake Science 2016年第1期29卷 35-43页

作者： Jeen-Hwa Wang Institute of Earth Sciences Academia Sinica

During the ruptures of an earthquake, the strain energy, AE, will be transferred into, at least, three parts, i.e., the seismic radiation energy （Es）, fracture energy （Eg）, and frictional energy （Ef）, that is, AE = Es ＋ Eg ＋ El. Friction, which is represented by a velocity- and state-de- pendent friction law by some researchers, controls the three parts. One of the main parameters of the law is the char- acteristic slip displacement, De. It is significant and nec- essary to evaluate the reliable value of Dc from observed and inverted seismic data. Since Dc controls the radiation efficiency, ηR = Es/（Es ＋ Eg）, the value of qR is a good constraint of estimating Dc. Integrating observed data and inverted results of source parameters from recorded seis- mograms, the values of Es and Eg of an earthquake can be measured, thus leading to the value of ηR. The constraint used to estimate the reliable value of Dc will be described in this work. An example of estimates of Dc based on the observed and inverted values of source parameters of the September 20, 1999 Ms 7.6 Chi-Chi （Ji-Ji）, Taiwan region, earthquake will be presented.

关键词： Characteristic slip displacement Seismicradiation energy Fracture energy radiation efficiency

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Constraints on rupture speed of the 2001 MS 8.1 West Kunlun Mountain Pass earthquake by co-seismic surface rupture slip displacements based on the slip-weakening mechanism with frictional undershoot involved

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Acta Seismologica Sinica(English Edition) 2008年第3期21卷 219-232页

作者：史保平杨勇 College of Earth Science Graduate University of Chinese Academy of Sciences Institute of Geophysics China Earthquake Administration

With co-seismic surface rupture slip displacements provided by the field observation for the 2001 MS8.1 West Kunlun Mountain Pass earthquake, this paper estimates the rupture speed on the main faulting segment with a long straight fault trace on the surface based on a simple slip-weakening rupture model, in which the frictional overshoot or undershoot are involved in consideration of energy partition during the earthquake faulting. In contrast to the study of Bouchon and Vallée, in which the rupture propagation along the main fault could exceed the local shear-wave speed, perhaps reach the P-wave speed on a certain section of fault, our results show that, under a slip-weakening assumption combined with a frictional undershoot (partial stress drop model), average rupture speed should be equal to or less than the Rayleigh wave speed with a high seismic radiation efficiency, which is consistent with the result derived by waveform inversion and the result estimated from source stress field. Associated with the surface rupture mechanism, such as partial stress drop (frictional undershoot) associated with the apparent stress, an alternative rupture mechanism based on the slip-weakening model has also been discussed.

关键词： slip-weakening model partial stress drop frictional undershoot apparent stress rupture speed radiation efficiency

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Efficient Terahertz Photoconductive Emitters with Improved Electrode Structures

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Journal of Electronic Science and Technology 2014年第2期12卷 156-160页

作者： Ying-Xin Wang Yi-Jie Niu Wei Cheng Zhi-Qiang Li Zi-Ran Zhao the Key Laboratory of Particle & radiation Imaging of Ministry of Education Tsinghua University China Nuclear Power Engineering Co. Ltd Nuctech Company Limited

We present the design, fabrication, and characterization of two new types of terahertz photoconductive emitters. One has an asymmetric four-contact electrode structure and the other has an arc-shaped electrode structure, which are all modified from a traditional strip line antenna. Numerical simulations and real experiments confirm the good performance of the proposed antennas. An amplitude increase of about 40% is experimentally observed for the terahertz signals generated from the new structures. The special electrode structure and its induced local bias field enhancement are responsible for this radiation efficiency improvement. Our work demonstrates the feasibility of developing highly efficient terahertz photoconductive emitters by optimizing the electrode structure.

关键词： Electrode structure photoconductive antenna radiation efficiency terahertz

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Study on Antenna efficiency in Metal Box with a Small Opening Slot

Study on Antenna Efficiency in Metal Box with a Small Openin...

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2019年全国天线年会

作者： Wen Sichao Dong Yuandan University of Electronic Science and Technology of China

The overall radiation efficiency of WIFI 2.4 GHz antennas in a metal box with a small opening slot is investigated in this *** overall size of the metal box is 85×55×11 mm, while the slot on the metal box is set to be 3 ×8 *** different antennas are *** I is a planar inverted-F antenna(PIFA) and Antenna Ⅱ is a meander-line folded *** results verify that an isolated antenna placed inside a metal box could barely radiate through a small opening even it is close to the *** connected to the outside surface of the metal box and utilize the ground current on the box could we achieve relatively good radiation which is suitable for real ***,when antenna is placed to the inside surface of the top box metal the antenna radiation efficiency drops significantly due to skin effect which reduces ground surface radiation.

关键词： meander-line folded monopole metal box planar inverted-F antenna(PIFA) radiation efficiency

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