Wideband planar filters with an extended stopband

An approach to the construction of wideband bandpass filters of microstrip and stripline designs, which have an extended stopband and can incorporate lumped capacitors, is proposed. This approach is based on resonators with the enhanced frequency diversity of fundamental and parasitic resonance frequencies and coupling circuits formed according to an assigned rule. The potential of the filters achieved due to the proposed technique is established. In particular, a very wide passband whose ratio of cuttoff frequencies is 5: 1, as well as the stopband greater than an octave at a level of 40 dB, is demostrated to be attainable. When the passband is narrower, the stopband can exceed two octaves. The given approach can be applied to filters operating in a broad frequency range, including to that corresponding to centimeter and meter waves. The experimental data are presented.     

基于超材料的多频带可调谐太赫兹吸收器

设计了一种多频带可调谐的太赫兹超材料吸收器。在超材料吸收器的结构中,引入光敏半导体硅材料,设计特殊的顶层金属谐振器,分析开口长度、线宽、介质层厚度等参数尺寸对太赫兹超材料吸收器的吸收光谱特性影响。根据光照与光敏半导体硅电导率之间的关系,研究太赫兹超材料吸收器的频率调谐特性。仿真结果得到太赫兹波段的12个吸收频率调制,其中有10处吸收峰的吸收率超过90%近完美吸收,且有6处吸收率达到99%的完美吸收,而且吸收率调制深度和相对带宽分别达到85.9 %和85.5%,具有很强的可调谐特性。设计的光激励太赫兹超材料吸收器结构简单,具有多频带可调谐和完美吸收特性,扩大了吸收器的应用范围。     

Methods for extension of the rejection band of microwave devices on the basis of planar modified mushroom-shaped metamaterial structures

Methods for extension of the rejection band of microwave devices on the basis of planar modified mushroom-shaped metamaterials comprising either two-layered topological structures with frequency-selective surfaces or multilayer bulk structures with intermediate layers containing split-ring resonators are proposed. Computer simulation of such devices, clearly demonstrating a twoto six-fold extension of the rejection band is performed. Experimental results confirming the results of numerical simulation are presented.     

基于石墨烯超材料的三频段可调谐完美吸收器

为进一步降低太赫兹频率下高性能调控器件的结构复杂度,提出一种三频段可调谐超材料完美吸收器.该吸收器由图案化的石墨烯层和经Si介质层隔开的Au接地平面组成,利用太赫兹下的石墨烯表面等离子体共振以及图案化石墨烯与电场耦合提供的电偶板子共振形成多个吸收峰.数值仿真结果表明,在0.489 THz、1.492 THz和2.437...     

A compact tunable metamaterial filter based on split-ring resonators

A tunable metamaterial filter is designed based on split-ring resonators (SRRs) in this paper. The metamaterial filter has a compact size of 15 mm×20 mm, and miniaturization is realized by using the SRRs. By loading tunable devices, the continuous operation of the filter is realized at X band (from 10.7 GHz to 12 GHz), the bandwidth is about 13%, the minimum return loss is 35 dB, and the maximum insertion loss is 0.37 dB. The results illustrate that the metamaterial filter shows the compact size, wide bandwidth and good band pass characteristics. This work has been supported by the Key Laboratory Foundation of China Electronics Technology Group Corporation (No.ZX15ZS391), the National Fund for International Cooperation in Science and Technology (No.2014DFR10020), and the Natural Science Foundation of Shanxi Province (Nos.2014021020-1 and 2015021083). E-mail:798710363@qq.com      

Reflection of a surface mode from the end of a planar metamaterial waveguide

Variational method is used for the analysis of the problem of surface mode reflection from the end of a planar dielectric waveguide fabricated from a metamaterial. The theory is illustrated by the examples of the ends of three-layer symmetric waveguides with piecewise constant profiles of their permittivities and permeabilities.     

A metamaterial terahertz modulator based on complementary planar double-split-ring resonator

A metamaterial based on complementary planar double-split-ring resonator (DSRR) structure is presented and demonstrated, which can optically tune the transmission of the terahertz (THz) wave. Unlike the traditional DSRR metamaterials, the DSRR discussed in this paper consists of two split rings connected by two bridges. Numerical simulations with the finite-difference time-domain (FDTD) method reveal that the transmission spectra of the original and the complementary metamaterials are both in good agreement with Babinet’s principle. Then by increasing the carrier density of the intrinsic GaAs substrate, the magnetic response of the complementary special DSRR metamaterial can be weakened or even turned off. This metamaterial structure is promised to be a narrow-band THz modulator with response time of several nanoseconds.     

Design of an ultra compact electronically tunable microwave impedance transformer

A novel ultra compact microwave tuneable impedance transformer topology is proposed. It consists of a classical /spl pi/ CLC network where an equivalent tuneable inductance is realised with a high impedance transmission line in series with fixed inductance and a diode's varactors. The realised hybrid prototype at 900 MHz operating frequency is only 0.06/spl lambda/-long. Impedance loads from 16.5 to 280 /spl Omega/ can be matched with a return loss better than -20 dB, and the relative bandwidth equals /spl plusmn/36% for a fixed 50 /spl Omega/ load.     

基于单个CDCTA的低压电控调谐电流模式多相位正弦振荡器的设计

提出了一种全新的电流模式多相位正弦振荡器电路。该电路仅使用一个电流差分级联跨导放大器(CDCTA)和接地无源元件,能产生n(n为奇或偶)个等相位差的电流信号,电路结构简单、工作电压低、输出阻抗高、振荡频率高,而且振荡条件和振荡频率独立可调。计算机CADENCE软件仿真和流片测试结果验证了理论分析的正确性。     

Fundamental modes of a nonsymmetric planar metamaterial waveguide

The properties of fundamental (lower) guided wave modes propagating in a nonsymmetric planar metamaterial waveguide are considered. A graphical approach is applied for the analysis of their dispersion characteristics oriented toward the determination of the waveguide’s parameters ensuring the propagation of these waves in the waveguide. It is shown that, a nonsymmetric waveguide, as a symmetric one, can support both forward and backward wave modes.     

AT89S52多路电压控制器实现特异材料天线电扫描

电控波束扫描天线在智能通讯和新一代导航系统有着广阔的应用前景,针对智能特异材料实现电控波束扫描天线的应用设计了多路电压控制器,该多路电压控制器可以通过调控节点处直流偏压实现对这类材料等效电磁参量的实时调控,从而实现传输线泄漏波天线的波束扫描、减小旁瓣等功效.     

Transient analysis of an electronically tunable dye laser--Part I: Simulation study

Computer simulation results of a dye laser electronically tuned by an acoustooptic filter in the laser cavity are presented. The filter employs a nonlinear anisotropic crystal in which a colinear acoustic beam diffracts the light into the orthogonal polarization. Only a narrow wavelength band is constructively diffracted and since the band center is determined by the acoustic frequency, it is easily controlled electronically. The filter causes the frequency of the light to shift by twice the acoustic frequency in a round trip and so the usual laser resonance condition is not satisfied. The simulation indicates that the previously predicted steady-state results are attained under CW pumping conditions. With a representative CaMoO4fillter, approximately 3 μs are required to achieve the steady state and a 0.3 Å spectral bandwidth is typical. Similarly a LiNbO3filter requires 150 ns and produces a 0.17-Å spectral bandwidth. Results of simulation studies for pulsed operation are also included.     

The fundamental modes of a symmetrical planar metamaterial waveguide

The dispersion properties of the fundamental (lower order) surface wave modes of a symmetrical planar metamaterial waveguide are considered. A qualitative graphical method is applied to analyze the dispersion characteristics of the waveguide modes.     

双阻带红外频率选择表面的设计

为实现在中、远红外两个大气窗口的低透过率,设计了一种基于六边形环状结构的双屏红外频率选择表面（FSS）,利用CST电磁软件进行仿真分析,发现该FSS在3~5 m和8~14 m两个波段内的平均透过率低于2.5%,实现了红外波段的双阻带;采用表面电流模式分析法和有效介质理论分析了该FSS的滤波机理,发现不同谐振点处由于屏间耦合或屏内单元间的耦合在谐振单元表面感应出对称分布的电流从而使散射总场增强,形成增强型反射,即比较理想的红外光阻带;最后研究了电磁波的极化方式、入射角度、介质属性以及结构参数对FSS传输特性的影响。结果表明该FSS具有良好的偏振稳定性和角度稳定性,介质属性和结构参数对其传输特性有较大影响。     

A metamaterial based on a 2D two-element lattice of cylinders with right- and left-handed surface conductivity

A new method is proposed for calculating the effective constitutive parameters of small-period 2D lattices. A two-element lattice of resonance chiral cylindrical scatterers with the opposite signs of chirality is investigated. It is found that such a structure exhibits the properties of the Veselago medium in a narrow frequency band.     

基于局部表面等离子体激元的共振增强超材料吸收器的吸收性质

提出了一种在150～165 THz区域内的具有单峰吸收特性的高性能超材料吸收器。设计的吸波器包含两个阵列:双金属颗粒阵列和双空气孔阵列。金属层的阻尼常数在模拟中被优化。发现在模拟中使用2. 3倍的阻尼常数时,可以获得最大吸收率96%。吸收峰由局域表面等离子体(LSP)模式共振激发。为了揭示共振电磁机理,进行了两组模拟,研究结构参数变化对共振吸收峰的影响。发现随着垂直距离V的增加,吸收峰被增强,当V=160 nm时,获得新的吸收带。在第二次模拟中,对于水平距离H的增加,吸收峰也增强,并且当H=190 nm时获得另一个新的吸收带。电场强度分布结果表明LSP模式的激发和LSP模式之间的耦合效应导致吸收峰增强现象。     

Propagation of electromagnetic waves in planar metamaterial waveguides and radiation of antennas based on such waveguides

Propagation of electromagnetic waves in planar waveguides made of metamaterials with negative values of the relative permittivity and relative permeability is analyzed. The specific features of radiation from antennas manufactured on the basis of planar metamaterial waveguides are studied. It is shown that radiation of such antennas is characterized by the backfire radiation effect, i.e., the maximum of the radiation pattern is formed at 180°. The causes of this effect and the conditions for its appearance are revealed. It is proved that this effect appears only in the antennas manufactured on the basis of metamaterial waveguides with negative values of the relative permittivity and relative permeability. A design version of a scanning two-mode antenna operating on the basis of this effect is proposed.     

一种超材料的平面型频率选择反射面特性研究

为降低频率选择反射面的设计维度和制造成本,研究了开口谐振环的结构尺寸对谐振点的影响,提出了一种双面印制型开口谐振环(Split-Ring Resonators,SRR)结构.利用负磁导率超材料,设计了一种双面印制型SRR结构,在平面内对SRR正交排列形成双面印制型频率选择反射面,对馈源频段的垂直极化波反射,而对其它频段来波透射.通过对新型频率选择反射面的测试,测试结果表明符合设计频率选择反射面(Frequency Selective Reflector,FSR)的反射性能.     

准分子激光泵浦的可调谐染料激光的研究

用KrF准分子激光泵浦PTP染料,在甲醇、乙醇、环已烷和二(口恶)烷四种溶剂中得到了紫外激光,调谐范围为335.8～345.9毫微米,激光线宽约8埃。用乙醇作溶剂时激光转换效率为21％。