热点论文带您领略未来通信在材料领域研究的最新进展——图书馆前沿文献专题推荐服务（44）

2021-06-25

 

        在上一期前沿文献中推荐中，介绍了未来通信在海空领域研究的最新进展，包括：天空是移动覆盖的边缘、用于海上物联网的蜂窝通信研究、具有自适应波束成形和服务时间分配的RIS辅助离岸通信，以及关于海空VSAT通信安全性研究。
在本期的文献推荐中，关注点着眼于未来通信在材料领域研究的最新进展，包括：一种用于千兆数据速率反向散射通信的印刷毫米波调制器和天线阵列、基于自适应阻抗匹配技术的射频前端系统功率传输优化、基于电感调谐改进分裂环谐振器的近零折射率（NZI）超材料四频段epsilon negative（ENG）多频段天线性能增强，以及离子晶体中声子极化激元对THz频率光学非线性的巨大增强。供相关领域的科研人员参考。
 
领域一 一种用于千兆数据速率反向散射通信的印刷毫米波调制器和天线阵列
A printed millimetre-wave modulator and antenna array for backscatter communications at gigabit data rates
John Kimionis, etc.
Nature Electronics, 2021
Future devices for the Internet of Things will require communication systems that can deliver higher data rates at low power. Backscatter radio—in which wireless communication is achieved via reflection rather than radiation—is a low-complexity approach that requires a minimal number of active elements. However, it is typically limited to data rates of hundreds of megabits per second because of the low frequency bands used and the modulation techniques involved. Here we report a millimetre-wave modulator and antenna array for backscatter communications at gigabit data rates. This radiofrequency front-end consists of a microstrip patch antenna array and a single pseudomorphic high-electron-mobility transistor that supports a range of modulation formats including binary phase shift keying, quadrature phase shift keying and quadrature amplitude modulation. The circuit is additively manufactured with inkjet printing using silver nanoparticle inks on a flexible liquid-crystal polymer substrate. A millimetre-wave transceiver is also designed to capture and downconvert the backscattered signals and route them for digital signal processing. With the system, we demonstrate a bit rate of two gigabits per second of backscatter transmission at millimetre-wave frequencies of 24–28 GHz, and with a front-end energy consumption of 0.17 pJ per bit.
 
领域二 基于自适应阻抗匹配技术的射频前端系统功率传输优化
Optimum power transfer in RF front end systems using adaptive impedance matching technique
Mohammad Alibakhshikenari, etc.
Scientific Reports, 2021
Matching the antenna’s impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna’s radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence (< 5 µs) and is highly accurate for autonomous adaptive antenna matching networks.
 
领域三 基于电感调谐改进分裂环谐振器的近零折射率（NZI）超材料四频段epsilon negative（ENG）多频段天线性能增强
Inductively tuned modified split ring resonator based quad band epsilon negative (ENG) with near zero index (NZI) metamaterial for multiband antenna performance enhancement
Md Moniruzzaman, etc
Scientific Reports, 2021
An inductively tuned modified split-ring resonator-based metamaterial (MTM) is presented in this article that provides multiple resonances covering S, C, X, and Ku-bands. The MTM is designed on an FR-4 substrate with a thickness of 1.5 mm and an electrical dimension of 0.063λ × 0.063λ where wavelength, λ is calculated at 2.38 GHz. The resonator part is a combination of three squared copper rings and one circular ring in which all the square rings are modified shaped, and the inner two rings are interconnected. The resonance frequency is tuned by adding inductive metal strips in parallel two vertical splits of the outer ring that causes a significant shift of resonances towards the lower frequencies and a highly effective medium ratio (EMR) of 15.75. Numerical simulation software CST microwave studio is used for the simulation and performance analysis of the proposed unit cell. The MTM unit cell exhibits six resonances of transmission coefficient (S21) at 2.38, 4.24, 5.98, 9.55, 12.1, and 14.34 GHz covering S, C, X, and Ku-bands with epsilon negative (ENG), near-zero permeability, and near-zero refractive index (NZI). The simulated result is validated by experiment with good agreement between them. The performance of the array of the unit cells is also investigated in both simulation and measurement. The equivalent circuit modeling has been accomplished using Advanced Design Software (ADS) that shows a similar S21 response compared to CST simulation. Noteworthy to mention that with the copper backplane, the same unit cell provides multiband absorption properties with four major absorption peaks of 99.6%, 95.7%, 99.9%, 92.7% with quality factors(Q-factor) of 28.4, 34.4, 23, and 32 at 3.98, 5.5, 11.73 and 13.47 GHz, respectively which can be applied for sensing and detecting purposes. The application of an array of the unit cells is investigated using it as a superstrate of an antenna that provides a 73% (average) increase of antenna gain. Due to its simple design, compact dimension with high EMR, ENG property with near-zero permeability, this multiband NZI metamaterial can be used for microwave applications, especially for multiband antenna gain enhancement.
 
领域四 离子晶体中声子极化激元对THz频率光学非线性的巨大增强
Giant enhancement of THz-frequency optical nonlinearity by phonon polariton in ionic crystals
Yao Lu, etc.
Nature Communications, 2021
The field of nonlinear optics has grown substantially in past decades, leading to tremendous progress in fundamental research and revolutionized applications. Traditionally, the optical nonlinearity for a light wave at frequencies beyond near-infrared is observed with very high peak intensity, as in most materials only the electronic nonlinearity dominates while ionic contribution is negligible. However, it was shown that the ionic contribution to nonlinearity can be much larger than the electronic one in microwave experiments. In the terahertz (THz) regime, phonon polariton may assist to substantially trigger the ionic nonlinearity of the crystals, so as to enhance even more the nonlinear optical susceptibility. Here, we experimentally demonstrate a giant second-order optical nonlinearity at THz frequency, orders of magnitude higher than that in the visible and microwave regimes. Different from previous work, the phonon-light coupling is achieved under a phase-matching setting, and the dynamic process of nonlinear THz generation is directly observed in a thin-film waveguide using a time-resolved imaging technique. Furthermore, a nonlinear modification to the Huang equations is proposed to explain the observed nonlinearity enhancement. This work brings about an effective approach to achieve high nonlinearity in ionic crystals, promising for applications in THz nonlinear technologies.
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