一种基于电磁超材料的大规模天线阵列天线罩解耦技术

文中设计了一种去耦天线罩,为解决紧凑排列的大规模天线阵列中相邻端口隔离度较低的问题提供了参考.天线罩主体是一层具有低介电常数和低损耗性的介质板,其上印刷了周期性排列的金属贴片结构.通过调整金属贴片的形状以及天线罩到天线阵列的距离,使天线罩产生的反射波与阵中的耦合波幅度相同、相位相反,二者相互抵消,达到增加阵中端口间隔离...     

光调制超材料及其传感应用

研究了一种太赫兹光调制超材料传感器。该器件由金属-半导体复合结构（开口谐振环（SRR））和柔性聚酰亚胺衬底组成。光敏硅材料填充在器件上方的两个开口处。模拟结果表明,通过改变外激励泵浦光的功率,光敏硅的电导率发生改变,从而实现对复合超材料结构谐振峰的调制。进一步分析该结构在谐振频率下的电场和表面电流密度分布情况,讨论了其物理机制。此外,随着待测溶液（氯化钙）浓度变化,传感器谐振峰发生红移,其灵敏度为11.4 GHz/M。该器件可作为太赫兹波段液体传感器使用。     

超材料宽带低散射技术研究进展

电磁吸波材料和外形设计等低散射技术被广泛应用于隐身、电磁屏蔽及无线通信等领域。相比于传统技术途径,超材料低散射技术具有更加灵活的设计和调控能力,因而在带宽拓展、厚度减低等设计要求上具有更好的发展前景。文章介绍了实现宽频带散射缩减的常用方案,并着重介绍了基于多谐振叠加、损耗调节以及漫反射原理的带宽拓展方法,并简要展望了低散射技术的发展趋势。     

Metamaterial‐inspired miniaturized antenna loaded with IDC and meander line inductor using partial ground plane

In this article, a novel omnidirectional compact dual band metamaterial‐inspired antenna with CPW feed has been proposed for application of GSM 1800 (1.71‐1.785 GHz/1.805‐1.879 GHz), GSM 1900 (1.85‐1.91 GHz/1.93‐1.99 GHz), UMTS (1.92‐2.17 GHz), WLAN/Wi Fi (4.9, 5, 5.9 GHz), HiperLAN1 (5.15‐5.3 GHz), and HiperLAN2 (5.47‐5.72 GHz) using a combination of meander line inductor and interdigital capacitor (IDC). The antenna consists of complimentary right/left handed (CRLH) transmission line on both sides of patch to excite zeroth order mode (n = 0). The rectangular slotted stubs act as a virtual ground for the structure using a short circuit condition at the end of the IDC. The zeroth order resonance (ZOR) frequency is mainly controlled by IDC and partially with the meander line inductor. The designed antenna operates from 1.72 to 2.22 GHz and 4.25 to 5.88 GHz with radiating size of 0.56λ_o × 0.35λ_o (32 × 20 mm²), where λ_o is the free‐space wavelength at ZOR frequency of 5.27 GHz. The proposed antenna offers measured impedance bandwidth (|S₁₁| <?10 dB) of 25.3 and 18.7% at 1.95 and 5.28 GHz and covers the targeted frequency bands. The proposed structure offers omnidirectional radiation patterns are congruous throughout the working band.     

Directivity enhancement of wire monopole antenna using magnetic metamaterials

This article proposes the use of a magnetic metamaterial (MTM) slab over the ground plane of a wire monopole antenna to improve its directivity. In this regard, mu very large (MVL) behavior of the metamaterial is utilized for enhancing the directivity of the monopole. Despite the directivity enhancement of about 5 dB, an improved bandwidth of 35% is obtained for the proposed configuration. Initially, a 2 × 3 array of a single MTM slab has been placed over the ground plane of the monopole. It is shown that, over the whole working band, a significant directivity improvement is maintained compared to the unloaded monopole. Further, the directivity performance has been investigated with different combination of MTM slab.     

Asymmetric dual‐band linear‐to‐circular converter by bi‐layered chiral metamaterial

In this article, we present a dual‐band linear‐to‐circular transparent converter by bi‐layered chiral metamaterial (CMM) with an inverted “G” array in microwave region. The proposed metasurface consists of three layers which are the upper layer of the metasurface with a periodic regular metallic inverted “G” and wire array, the dielectric layer, and the bottom layer operating as chiral symmetric structure of the upper. The simulation results show that the transmitted right‐circular polarized wave with the axial ratio of 3 dB or less is in the range of 8.6‐10.9 GHz and the left‐circular polarized wave is within 18.1‐22.5 GHz when y‐polarized forward wave is normally incident. Specifically, the polarization conversion transmission can be maintained at over 85% at angle of incidence up to 40°. Therefore, the proposed CMM device is useful for the development of the integrated polarization manipulation devices.     

All-optical tunable dual Fano resonance in nonlinear metamaterials in optical communication range

Low-power, ultra-fast all-optical tunable dual Fano resonance was realized in a metamaterial coated with a non-linear nanocomposite layer composed of gold nanoparticle-doped polycrystalline barium strontium titanate and multilayer tungsten disulphide microsheets. A high non-linear refractive index of ?2.148 × 10^?11 m²/W was achieved in the nanocomposite material that originated in the non-linearity enhancement associated with the quantum confinement effect, the local-field enhancement effect, and reinforced interactions between photons and the multilayer tungsten disulphide microsheets. An ultra-low threshold pump intensity of 600 kW/cm² was obtained. An ultra-fast response time of 25.4 ps was maintained because of the fast relaxation dynamics of the bound electrons in the nanoscale polycrystalline barium strontium titanate grains. The large third-order non-linear responses of the metamaterial were confirmed with a high third harmonic generation conversion efficiency of 5.4 × 10^?5. This work may help to pave the way towards realization of ultra-high-speed information processing chips and multifunctional integrated photonic devices based on metamaterials.     

A CPW‐fed band notched wideband circularly polarized ZOR antenna based on CRLH‐TL approach

This article presents design and analysis of three wide band zeroth‐order resonance antennas (antennas I, II, and III) using composite right and left‐handed transmission line (CRLH‐TL) approach. Coplanar waveguide technology, single layer via‐less structures are used to have the design flexibility. The bandwidth characteristics are analyzed by using lumped parameters of CRLH‐TL. By introducing a simple slot in the ground plane of antenna I both bandwidth enhancement and circularly polarization characteristics are achieved in antenna II. Another quarter wave L‐shaped slot has been introduced in the ground plane of antenna II to introduce a notch band in the frequency response of antenna III. Achieved measured 10 dB return loss bandwidth of antenna I and antenna II are 960 (3.3‐4.26 GHz) and 2890 MHz (2.77‐5.66 GHz), respectively. Antenna III offers measured 10 dB return loss bandwidth of 3220 MHz (2.32‐5.54 GHz) with a band notch from 2.39 to 2.99 GHz that isolates the 2.4 GHz WLAN and 3.5 GHz WiMAX band. Antenna II and antenna III have circular polarization property with measured axial ratio bandwidth of 440 MHz. The measured peak realized gain of antennas II and III is around 1.53‐2.9 dBi.