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广东“双毫”与近代广州生活
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作者 蒙启宙 《广州城市职业学院学报》 2017年第3期17-23,共7页
清朝晚期,广州在全国率先开铸机制银币,"双毫"脱颖而出,成为反映广州近代生活的一面镜子。文章通过大量鲜活的一手史料,对"双毫"背后的各种社会经济文化生活进行剖析和探讨,挖掘"双毫"本身的经济和文化内... 清朝晚期,广州在全国率先开铸机制银币,"双毫"脱颖而出,成为反映广州近代生活的一面镜子。文章通过大量鲜活的一手史料,对"双毫"背后的各种社会经济文化生活进行剖析和探讨,挖掘"双毫"本身的经济和文化内涵,为反思一种流通货币究竟在何种范围、何种程度上取得成功提供一例个案,为广州学的研究提供依据。 展开更多
关键词 双毫 近代广州 生活
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A Compact Millimeter Wave Antenna Array with Defected Ground Structure for 5G Applications
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作者 SHAKEEL Awais HAN Fang +1 位作者 ZAHOOR Sahar KHALEEQ Danish 《Journal of Donghua University(English Edition)》 CAS 2024年第5期557-568,共12页
The transition towards the fifth generation(5G)of communication systems has been fueled by the need for compact,high-speed and wide-bandwidth systems.These advancements necessitate the development of novel and highly ... The transition towards the fifth generation(5G)of communication systems has been fueled by the need for compact,high-speed and wide-bandwidth systems.These advancements necessitate the development of novel and highly efficient antenna designs characterized by the compact size.In this paper,a novel antenna design with a hexagonal-shaped resonating element and two U-shaped open-ended stubs is presented.Millimeter-wave(mmWave)frequency range suffers from attenuation due to atmosphere and path loss because of higher frequencies.To address these issues,the deployment of a high-gain antenna is imperative.This design is created through an evolutionary process to work best in the mmWave frequency range with a high gain.A thin Rogers RT5880 substrate with a thickness of 0.254 mm,a dielectric constant of 2.3 and a loss tangent of 0.0009 supports the copper-based radiating element.A partial ground plane with a square slot and trimmed corners at the bottom enhances the antenna’s bandwidth.The single-element antenna exhibits a wide bandwidth of nearly 6 GHz and a gain of 4.58 dBi.By employing the proposed antenna array,the antenna gain is significantly enhanced to 14.90 dBi while maintaining an ultra-compact size of 24 mm×46 mm at the resonant frequency of 31 GHz.The antenna demonstrates a wider impedance bandwidth of 15.73%(28-34 GHz)and an efficiency of 94%.The proposed design works well for 5G communication and satellite communication,because it has a simple planar structure and focused dual-beam radiation patterns from a simple feeding network. 展开更多
关键词 dual beam ultra-compact antenna array millimeter wave(mmWave) 5G high gain
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Simultaneous generation of 3G and millimeter-wave signals using a dual-electrode MZM in ROF systems
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作者 应祥岳 徐铁峰 +3 位作者 刘太君 聂秋华 文化锋 李军 《Optoelectronics Letters》 EI 2015年第4期286-289,共4页
A novel radio-over-fiber(ROF) scheme to simultaneously generate and transmit the 3rd generation telecommunication(3G) and millimeter-wave(MMW) signals by using a single dual-electrode Mach-Zehnder modulator(MZM) is pr... A novel radio-over-fiber(ROF) scheme to simultaneously generate and transmit the 3rd generation telecommunication(3G) and millimeter-wave(MMW) signals by using a single dual-electrode Mach-Zehnder modulator(MZM) is proposed.There is no apparent nonlinearity induced by the ROF system.By employing this analog ROF signal transmission technique,highly transparent fiber-wireless convergence networks can be realized,which are ideal for multi-standard wireless system operation. 展开更多
关键词 millimeter modulator transmit apparent analog multiplexing wideband nonlinearity bandwidth transparent
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