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1.
In this letter, we introduce a novel passive transmission line of negative refractive index （i.e., left-handedness） based on identical symmetrical lattice type structures [thus called ＂lattice type transmission line＂ （LT-TL）]. The dispersion characteristic and the transmission response of the proposed LT-TL are analyzed. While all the other left-handed passive transmission lines are of high pass, the present passive left-handed transmission line is of low pass. Compared with a conventional transmission line, the LT-TL has a phase shift of 180° in the entire wide pass-band. 相似文献
2.
INTRODUCTION Left-handed materials (LHMs) with negative permittivity and negative permeability, first theo- retically investigated by Veselago (1968), have at- tracted much interest in the past few years (Smith et al., 2000; Pendry, 2000). Such materials were first implemented using a structure which combined pe- riodic arrays of metallic lines and split ring resonators (SRRs) (Shelby et al., 2001). Since then much work has been dedicated to fabricating such materials. These new artif… 相似文献
3.
INTRODUCTION Left-handed materials (LHMs), first investigated theoretically by Veselago (1968), have received sub- stantial attention in the scientific and engineering communities. The unique properties of these meta- materials are promising for a diversity of microwave applications, such as new types of beam steerers, modulators, filters, superlens (Pendry, 2000), cou- plers and antenna radoms (Smith et al., 2004). Re- cently, a transmission line (TL) approach has been successfully in… 相似文献
4.
INTRODUCTION In recent years metamaterials, more commonly referred to as left-handed materials, have stimulated great interests in the scientific and engineering field. These artificial materials, which were first theorized by Veselago (1968) and experimentally realized by Shelby et al.(2001), can exhibit specific electromag- netic properties not commonly found in nature. The approach of using transmission line theory was veri- fied to be an efficient design tool for metamaterials applica… 相似文献
5.
INTRODUCTION An artificial dielectric medium that exhibits si- multaneously negative electric permittivity and magnetic permeability, also known as a left-handed (LH) material, was first envisaged by Veselago, who theoretically predicted that such a medium would exhibit a negative refractive index (NRI) (Veselago, 1968). An artificial NRI medium exhibiting back- ward-wave propagation characteristics (and therefore a negative refractive index) was first realized ex- perimentally in (She… 相似文献
6.
INTRODUCTION Wave propagation in a material with negative magnetic permeability and negative electric permit- tivity was first theoretically analyzed by Veselago (1968). In such a left-handed material (LHM), the electric field E, the magnetic field H and the wave vector k of electromagnetic wave propagation obey the left-hand rule (instead of the right-hand rule for usual materials). After Smith et al.(2000) demon- strated simultaneously negative permeability and permittivity, using cop… 相似文献
7.
在综合分析了微带平面天线阵列馈电网络的两种传统馈电方式的基础上,提出了一种在微波工程应用中实际使用的一种新型馈电网络,提高学生理论知识与实践相结合的能力,更好的掌握最新技术发展。其新型馈电网络由一种左-右手混合微带传输线构成,可以获得高于传统并联馈电网络的天线阵列增益;同时,可以修正传统串联馈电网络的天线阵列辐射方向图的波束偏移,给出了一个工作频率为35GHz的2×2微带面阵的馈电网络设计案例,验证了其理论的正确性。 相似文献
8.
INTRODUCTION Veselago (1968) theoretically analyzed the wave propagation in a left-handed (LH) material which has simultaneously a negative magnetic permeability and a negative electric permittivity. The electric field, the magnetic field, and the wave vector of an electro-magnetic wave propagating in such a material obey the left-hand rule (instead of the right-hand rule for usual materials). Such an LH material was first real-ized in 2001 in microwave region with an array of metallic … 相似文献
9.
HU Xin ZHANG Pu HE Sailing 《浙江大学学报(A卷英文版)》2006,7(10):1777-1780
A dual structure of composite right/left handed （CRLH） transmission line （TL） is analyzed in which an inductance LR is in parallel with a capacitance CL and a shunt capacitance CR is in series with an inductance LL. Both the distributed and lumped cases are considered. The dispersion diagram and transmission properties of the dual CRLH TL are given and compared with those of a standard CRLH TL. Contrary to the frequency response of a standard CRLH TL, a dual CRLH TL has a left-handed （negative phase shift） band at higher frequencies and a right-handed （positive phase shift） band at lower frequencies. A novel dual-band balun is presented as an application. 相似文献
10.
HU Xin HE Sailing 《浙江大学学报(A卷英文版)》2007,8(8):1179-1182
We propose a new class of negative refractive index transmission line in which ideal operational amplifiers are applied to form the periodically loaded negative-impedance-converted inductors and capacitors. The phase response of the new trans-mission line is opposite to that of a positive refractive index conventional transmission line. Unlike the existing negative refractive index transmission line,the new negative refractive index transmission line is non-dispersive and thus can lead to many novel applications such as designing new broadband devices. 相似文献
11.
INTRODUCTION Left-handed materials (LHMs) are characterized by simultaneously negative permittivity and perme- ability. It was first investigated theoretically by Ve- selago (1968). The experimental realization of LHM with resonance structures was demonstrated by Smith et al.(2000). Since then, LHM has gained significant interest and started to be integrated into novel mi- crowave and optical applications. The transmis- sion-line (TL) approach was recently proposed to realize LHMs … 相似文献
12.
Transmission properties of fractal Cantor distribution with left-handed materials (LHM) are investigated. The transmittance
and reflectance spectra can be calculated by using the optical transmission matrix method. Comparing with the conventional
Cantor multilayers, these structures with LHM have double functions of stopbands and defects. Through adjusting the thickness
of dielectric layers, the properties of stopbands and defects can be obtained, respectively. For stopbands, a broad stopband
filter is studied. For defect modes, multi-frequencies narrow passband filters are proposed. 相似文献
13.
使用飞秒瞬态反射-透射技术研究了金和铜纳米薄膜的电子和晶格动力学,应用双温和Curde近似模型分析了金属薄膜的非平衡热传导动力学.假设在瞬态反射中电子-晶格耦合常数为常数的情况下,计算超快脉冲加热后的电子和晶格温度.金和铜纳米薄膜的反射和透射信号在初始2 ps内相似,随后时间里信号明显不同,透射模式下的电子-晶格耦合效应要比反射模式下的更强和更敏感.这是由于沿着膜厚方向的温度变化受到金属薄膜和基底间的界面散射影响造成的.在研究半透明薄膜的超快动力学过程中,需要同时考虑反射和透射情况. 相似文献
14.
Broadband phase shifters are mostly proposed and fabricated based on the scheme proposed by Shiffman, which uses a coupled line with far ends connected together and a uniform transmission line to give a differential phase shift. Based on the unique dispersion property of the composite right/left-handed (CRLH) metamaterial structure, a new configuration is presented in this paper for fabricating the broadband differential phase shifter, which employs a novel CRLH metamaterial structure as one of the differential phase-shift arms, instead of the conventional coupled line. The new circuit can achieve a phase shift of 90° in an operational bandwidth as broad as one octave and its phase deviations are quite small. An original design of the novel broadband phase shifter is presented, in which the artificial CRLH structure was implemented by microstrip quasi-lumped elements. Both the simulated and measured results of the 90° broadband differential phase shifter are presented. 相似文献
15.
In this paper, we summarize some recent activities in the field of metamaterial research at the National University of Singapore （NUS）. Integral equations are applied for electromagnetic modelling of supernatural materials. Some special characteristics of the metamaterials are shown. Moreover, quasi-static Lorentz theory and numerical method （i.e., the method of moments for solving the electric field integral equation） and the transmission line theory are both presented to obtain the effective constitutive relations of metamaterials, respectively. Finally, feasibility of fabricating metamaterials based on analysis of equivalent transmission line model in the microwave spectrum and even higher is also shown and correspondingly some broad-bandwidth and low-loss metamaterial structures are designed and synthesized. 相似文献
16.
The Ethernet passive optical network (EPON) is the next generation of broad-band network technique. A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units (ONUs). This article provides a novel dynamic bandwidth allocation algorithm, i.e. threshold dynamic bandwidth allocation (TDBA), which is based on adaptive threshold, to increase resource utilization. The algorithm uses ONU data-transmitting rate to adjust optical line terminal (OLT) receiving data threshold from an ONU. Simulation results show that this algorithm can decrease average packet delay and increase network throughput in a 10G EPON system. 相似文献
17.
INTRODUCTION Conventional materials have positive magnetic permeability and mostly positive electrical permittiv- ity. Veselago (1968) initially assumed a material with negative permittivity and permeability simultane- ously and theoretically demonstrated the abnormal electromagnetic properties. This material, referred to as left-handed material (LHM) or metamaterial, re- verses a basic feature of light, such as, the reversal of the Doppler shift for radiation, and negative refractive in… 相似文献
18.
运用MATLAB GUI平台进行编程仿真,以正三角排列的架空线路为例建立评价模型,对500kV输电线路周围的电磁环境进行仿真研究.分析了相导线对地高度、相间距离、分裂导线根数、分裂间距、分裂导线子导线半径的变化对工频电场、工频磁场、无线电干扰和可听噪声的影响,依据相关的限值要求提出了控制措施. 相似文献
19.
本文将时域有限差分方法(FDTD)用于光子晶体理论研究，计算了光子晶体的透射率频率分布；并依据此透射率频率分布，直观地给出了不同频率段的光在二维方型完整光子晶体和有缺陷光子晶体中的一些传输特性。 相似文献
20.
Three-layer slab waveguide with left-handed materials （LHM） is discussed using the Maxwell＇s equations and their equations of dispersion relation for TM modes are obtained. By seeking the power of the slab waveguide, their equations of effective thickness for TM modes are obtained. Furthermore, the interrelated equations for right-handed materials （RHM） slab waveguide are introduced and their curves plotted. To find new properties for LHM slab waveguide, the equations and their curves for the LHM and RHM slab waveguide are compared respectively. 相似文献