设计了一种结构简单、可在电路板单面上印刷的新型左手材料.该结构由周期性排列的"Ⅱ"组成,具有频带宽、损耗低、尺寸小等优点.该材料在一定频段内具有介电常数和磁导率同时为负的特性.仿真结果表明:在8.79—15.57 GHz频率范...设计了一种结构简单、可在电路板单面上印刷的新型左手材料.该结构由周期性排列的"Ⅱ"组成,具有频带宽、损耗低、尺寸小等优点.该材料在一定频段内具有介电常数和磁导率同时为负的特性.仿真结果表明:在8.79—15.57 GHz频率范围内,折射率实部为负,而虚部接近于零;同时在该频段内的波阻抗实部大于零.从而说明该材料具有左手特性,在此基础上对该结构进行了制作、加工、并通过矩形波导法进行了验证.同时,该左手材料的相对带宽达到55.74%,而最大单元损耗仅是0.27 d B,远远优于传统的左手材料.展开更多
波导-微带过渡电路是连接毫米波、太赫兹系统中平面电路与波导的重要结构,直接影响系统性能。设计了一种中心频率220 GHz的矩形波导-悬置微带线过渡电路。过渡采用探针耦合的形式,并使用渐变线结构实现宽带阻抗匹配,这种结构具有结构紧...波导-微带过渡电路是连接毫米波、太赫兹系统中平面电路与波导的重要结构,直接影响系统性能。设计了一种中心频率220 GHz的矩形波导-悬置微带线过渡电路。过渡采用探针耦合的形式,并使用渐变线结构实现宽带阻抗匹配,这种结构具有结构紧凑,易于加工,宽带和插入损耗低等优点。最终的仿真结果表明:在180~255 GHz的频带内回波损耗优于20 d B,插入损耗小于0.18 d B。这种结构可广泛应用于毫米波、太赫兹平面电路中。展开更多
目的设计低损耗大芯径能量光纤涂料的配方并讨论其应用。方法以乙烯基硅油、巯基硅油、甲基丙烯酸三氟乙酯(TRIFEMA)、全氟十一烷基丙烯酸酯(FA)、氟橡胶、四氢呋喃丙烯酸酯GM61P00(THFA)和聚氨酯丙烯酸酯(PU)为主要组份,设计不同配方...目的设计低损耗大芯径能量光纤涂料的配方并讨论其应用。方法以乙烯基硅油、巯基硅油、甲基丙烯酸三氟乙酯(TRIFEMA)、全氟十一烷基丙烯酸酯(FA)、氟橡胶、四氢呋喃丙烯酸酯GM61P00(THFA)和聚氨酯丙烯酸酯(PU)为主要组份,设计不同配方的光纤涂料,并考察其折射率、透过率、凝胶含量和光纤损耗等性能,筛选最优配方。结果低损耗大芯径能量光纤涂料的最佳配比为m(乙烯基硅油)∶m(巯基硅油)∶m(TRIFEMA)=27∶5∶1,其涂层的折射率为1.392,透过率为99.23%(波长为850 nm时),制得大芯径能量光纤的抗拉强度为4392 MPa,传输损耗为6.6 d B/km。结论全氟化合物虽然能使涂料的折射率较低,但是其固化时存在缺陷,会导致光纤损耗较大。氟硅涂料具有优良的润湿性能,涂层附着力强,且各项性能指标均符合光纤使用要求。展开更多
In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly p...In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm3), that have extremely low relative permittivity (εr = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δ< 3 × 10−4 at 300 GHz) are synthetized by a template-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band.展开更多
This paper proposes a novel super junction （S J） SiGe switching power diode which has a columnar structure of alternating p- and n- doped pillar substituting conventional n- base region and has far thinner strained ...This paper proposes a novel super junction （S J） SiGe switching power diode which has a columnar structure of alternating p- and n- doped pillar substituting conventional n- base region and has far thinner strained SiGe p＋ layer to overcome the drawbacks of existing Si switching power diode. The SJ SiGe diode can achieve low specific on-resistance, high breakdown voltages and fast switching speed. The results indicate that the forward voltage drop of SJ SiGe diode is much lower than that of conventional Si power diode when the operating current densities do not exceed 1000 A/cm^2, which is very good for getting lower operating loss. The forward voltage drop of the Si diode is 0.66V whereas that of the SJ SiGe diode is only 0.52V voltages are 203 V for the former and 235 V for the latter. at operating current density of 10A/cm^2. The breakdown Compared with the conventional Si power diode, the reverse recovery time of SJ SiGe diode with 20 per cent Ge content is shortened by above a half and the peak reverse current is reduced by over 15%. The SJ SiGe diode can remarkably improve the characteristics of power diode by combining the merits of both SJ structure and SiGe material.展开更多
We demonstrate a low-loss terahertz waveguide based on the InAs-graphene-SiC structure. By analyzing the terahertz waveguide proposed in this paper, we can obtain that it is the characteristic of a low transmission lo...We demonstrate a low-loss terahertz waveguide based on the InAs-graphene-SiC structure. By analyzing the terahertz waveguide proposed in this paper, we can obtain that it is the characteristic of a low transmission loss coefficient （αloss 0.55 dB/m） for fundamental mode （LP01） when the incident frequency is larger than 3.0 THz. The critical radii of the inside and outside cylinders have been found for the high-quality transmission. The large inside radius and the high transmission frequency result in a fiat transmission loss coefficient curve. As a strictly two-dimensional material, the double graphene surface rings perform better to improve the quality of transmission mode. These results provide a new idea for the research of the long-distance THz waveguide.展开更多
文摘提出了一种基于多开口田字形单元结构实现材料左手特性的设计方案.该结构是在介质基板单侧集成电、磁谐振器形成左手单元.通过理论分析、软件仿真、加工测试、提取有效电磁参数,结果表明该结构在12.7—21.1 GHz范围内具有双负特性(等效介电常数ε<0,等效磁导率μ<0),基本覆盖Ku波段,绝对带宽可达8.4 GHz,单元损耗低于0.3 d B.同传统的左手材料相比,该结构以更小的单元尺寸,更低的损耗实现了更宽的左手频带,为宽频带、低损耗微波左手材料的设计及广泛应用提供了重要参考.
文摘设计了一种结构简单、可在电路板单面上印刷的新型左手材料.该结构由周期性排列的"Ⅱ"组成,具有频带宽、损耗低、尺寸小等优点.该材料在一定频段内具有介电常数和磁导率同时为负的特性.仿真结果表明:在8.79—15.57 GHz频率范围内,折射率实部为负,而虚部接近于零;同时在该频段内的波阻抗实部大于零.从而说明该材料具有左手特性,在此基础上对该结构进行了制作、加工、并通过矩形波导法进行了验证.同时,该左手材料的相对带宽达到55.74%,而最大单元损耗仅是0.27 d B,远远优于传统的左手材料.
文摘波导-微带过渡电路是连接毫米波、太赫兹系统中平面电路与波导的重要结构,直接影响系统性能。设计了一种中心频率220 GHz的矩形波导-悬置微带线过渡电路。过渡采用探针耦合的形式,并使用渐变线结构实现宽带阻抗匹配,这种结构具有结构紧凑,易于加工,宽带和插入损耗低等优点。最终的仿真结果表明:在180~255 GHz的频带内回波损耗优于20 d B,插入损耗小于0.18 d B。这种结构可广泛应用于毫米波、太赫兹平面电路中。
文摘目的设计低损耗大芯径能量光纤涂料的配方并讨论其应用。方法以乙烯基硅油、巯基硅油、甲基丙烯酸三氟乙酯(TRIFEMA)、全氟十一烷基丙烯酸酯(FA)、氟橡胶、四氢呋喃丙烯酸酯GM61P00(THFA)和聚氨酯丙烯酸酯(PU)为主要组份,设计不同配方的光纤涂料,并考察其折射率、透过率、凝胶含量和光纤损耗等性能,筛选最优配方。结果低损耗大芯径能量光纤涂料的最佳配比为m(乙烯基硅油)∶m(巯基硅油)∶m(TRIFEMA)=27∶5∶1,其涂层的折射率为1.392,透过率为99.23%(波长为850 nm时),制得大芯径能量光纤的抗拉强度为4392 MPa,传输损耗为6.6 d B/km。结论全氟化合物虽然能使涂料的折射率较低,但是其固化时存在缺陷,会导致光纤损耗较大。氟硅涂料具有优良的润湿性能,涂层附着力强,且各项性能指标均符合光纤使用要求。
基金The authors thank Kai Metsäkoivu for the technical assistance and Henrikki Liimatainen for providing us with nanocellulose materialsThe financial support received partly from EU Interreg Nord-Lapin liitto(project Transparent,conducting and flexible films for electrodes),Academy of Finland(6Genesis Flagship under Grant 318927)+1 种基金University of Oulu(projects Entity and PoC:Ultra-low permittivity and loss porous nanocomposites for future 6G telecommunication),Hungarian National Research,Development and Innovation Office through the projects GINOP-2.3.2-15-2016-00013 and GINOP-2.3.3-15-2016-00010the Ministry of Human Capacities,Hungary,grant 20391-3/2018/FEKUSTRAT is acknowledged.D.S.is thankful for the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.
文摘In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm3), that have extremely low relative permittivity (εr = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δ< 3 × 10−4 at 300 GHz) are synthetized by a template-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band.
基金Project supported by the National Natural Science Foundation of China (Grant No 50477012)the Doctoral Program Foundation of Institutes of Higher Education of China (Grant No 20050700006)the Special Scientific Research Program of the Education Bureau of Shaanxi Province,China (Grant No 05JK268)
文摘This paper proposes a novel super junction （S J） SiGe switching power diode which has a columnar structure of alternating p- and n- doped pillar substituting conventional n- base region and has far thinner strained SiGe p＋ layer to overcome the drawbacks of existing Si switching power diode. The SJ SiGe diode can achieve low specific on-resistance, high breakdown voltages and fast switching speed. The results indicate that the forward voltage drop of SJ SiGe diode is much lower than that of conventional Si power diode when the operating current densities do not exceed 1000 A/cm^2, which is very good for getting lower operating loss. The forward voltage drop of the Si diode is 0.66V whereas that of the SJ SiGe diode is only 0.52V voltages are 203 V for the former and 235 V for the latter. at operating current density of 10A/cm^2. The breakdown Compared with the conventional Si power diode, the reverse recovery time of SJ SiGe diode with 20 per cent Ge content is shortened by above a half and the peak reverse current is reduced by over 15%. The SJ SiGe diode can remarkably improve the characteristics of power diode by combining the merits of both SJ structure and SiGe material.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB339802)the National High Technology Research and Development Program of China(Grant No.2011AA010205)+3 种基金the National Natural Science Foundation of China(Grant Nos.61107086 and 61172010)the Natural ScienceFoundation of Tianjin,China(Grant Nos.11JCYBJC01100 and 13ZCZDSF02300)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120032110053)the THz Science and Technology Foundation of China Academy of Engineering Physics(Grant Nos.CAEPTHZ201201 and CAEPTHZ201304)
文摘We demonstrate a low-loss terahertz waveguide based on the InAs-graphene-SiC structure. By analyzing the terahertz waveguide proposed in this paper, we can obtain that it is the characteristic of a low transmission loss coefficient （αloss 0.55 dB/m） for fundamental mode （LP01） when the incident frequency is larger than 3.0 THz. The critical radii of the inside and outside cylinders have been found for the high-quality transmission. The large inside radius and the high transmission frequency result in a fiat transmission loss coefficient curve. As a strictly two-dimensional material, the double graphene surface rings perform better to improve the quality of transmission mode. These results provide a new idea for the research of the long-distance THz waveguide.
