University of Electronic Science and Technology of China

About: University of Electronic Science and Technology of China is a education organization based out in Chengdu, China. It is known for research contribution in the topics: Computer science & Antenna (radio). The organization has 50594 authors who have published 58502 publications receiving 711188 citations. The organization is also known as: UESTC.

Isolation Enhancement of a Very Compact UWB-MIMO Slot Antenna With Two Defected Ground Structures

Abstract: A very compact ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna with high isolation is presented in this letter. The proposed antenna, consisting of two UWB slot antennas, has a very compact size of $22 \times 26~\hbox{mm}^{2}$ , which is smaller than most of UWB antennas only with single antenna element. A T-shaped slot is etched on the ground to improve the impedance matching characteristic in the low-frequency and reduce the mutual coupling for the frequencies $ \geq 4~\hbox{GHz}$ . By etching a line slot to cancel out original coupling, isolation enhancement at the 3–4 GHz band is achieved. The antenna possesses a low mutual coupling of less than $ - 18~\hbox{dB}$ over the operating band from 3.1–10.6 GHz. The performance of this antenna both by simulation and by experiment indicates that the proposed antenna is a good candidate for UWB applications.

94 GHz Substrate Integrated Monopulse Antenna Array

Abstract: A planar W-band monopulse antenna array is designed based on the substrate integrated waveguide (SIW) technology The sum-difference comparator, 16-way divider and 32 × 32 slot array antenna are all integrated on a single dielectric substrate in the compact layout through the low-cost PCB process Such a substrate integrated monopulse array is able to operate over 93 ~ 96 GHz with narrow-beam and high-gain The maximal gain is measured to be 258 dBi, while the maximal null-depth is measured to be - 437 dB This SIW monopulse antenna not only has advantages of low-cost, light, easy-fabrication, etc, but also has good performance validated by measurements It presents an excellent candidate for W-band directional-finding systems

Improving Physical Layer Security Using UAV-Enabled Mobile Relaying

Abstract: Mobile relaying has aroused great interest in wireless communications recently, thanks to the rapid development and evolvement of unmanned aerial vehicles. This letter establishes the utility of mobile relaying in facilitating secure wireless communications. In particular, we consider transmit optimization in a four-node (source, destination, buffer-aided mobile relay, and eavesdropper) channel setup, wherein we aim at maximizing the secrecy rate of this system. However, the secrecy rate maximization problem is nonconvex and intractable to solve. To circumvent the nonconvexity, we exploit the difference-of-concave (DC) program to develop an iterative algorithm, which is proven to have Karush–Kuhn–Tucker point convergence guarantee. The algorithm conducts a water-filling-based solution in each DC iteration, and thus is computationally efficient to implement. In addition, for a given special case, we show that each DC iteration could yield a closed-form solution, which further reduces the computational complexity. Simulation results demonstrate that the proposed mobile relaying scheme could significantly outperform the static relaying scheme in terms of secrecy enhancement.

Ti3C2Tx (T = F, OH) MXene nanosheets: conductive 2D catalysts for ambient electrohydrogenation of N2 to NH3

Abstract: The Haber–Bosch process for industrial-scale NH3 production suffers from high energy consumption and serious CO2 emission. Electrochemical N2 reduction is an attractive carbon-neutral alternative for NH3 synthesis but is severely restricted due to N2 activation needing efficient electrocatalysts for the N2 reduction reaction (NRR) under ambient conditions. Here, we report that Ti3C2Tx (T = F, OH) MXene nanosheets act as high-performance 2D NRR electrocatalysts for ambient N2-to-NH3 conversion with excellent selectivity. In 0.1 M HCl, such catalysts achieve a large NH3 yield of 20.4 µg h−1 mgcat.−1 and a high faradic efficiency of 9.3% at −0.4 V vs. reversible hydrogen electrode, with high electrochemical and structural stability. Density functional theory calculations reveal that N2 chemisorbed on Ti3C2Tx experiences elongation/weakness of the NN triple bond facilitating its catalytic conversion to NH3 and the distal NRR mechanism is more favorable with the final reaction of *NH2 to NH3 as the rate-limiting step.