Design of compact two-port dual-band dual-polarized MIMO antenna for CBRS and WLAN sub-6-GHz applications

This communication presents a compact field de-correlation lines integrated dual band with dual-polarized (LP & CP) multiple-input multiple-output (MIMO) antenna for the fifth generation (5G) sub-6-GHz wireless communication systems. Dual working bandwidths, smaller interelement gaps, and superior isolation within the MIMO components are the distinguishing characteristics that give the proposed MIMO system an aspect of novelty. The modeled MIMO antenna has compact configurations of 20 × 21 × 0.8 mm³. The unit cell consists of a microstrip feed line with optimized rectangular slots branches etched from the radiated patch. The MIMO module is generated by the antiparallel replication of a single unit cell. To enhance the isolation, two rectangular slots are incorporated on the patch between the unit elements, which act as field de-correlation lines. The MIMO identity is supported by diversity performance calculations in terms of ECC, DG, and TARC. Simulated and measured counterparts are found in the agreement.     

Ultra-Wideband Electrostrictive Mechanical Antenna

Mechanical antennas based on piezoelectric materials can effectively reduce the size of long wave antennas down to 1/1000 of the wavelength (from km scale to mm level). However, the narrow bandwidth and weak field intensity seriously restrict its practical applications in transmission distance and channel capacity. Here, a mechanical antenna-based electrostrictive effect of relaxor ferroelectric ceramic (PMN-PT) is proposed to improve radiation capacity and achieve ultra-wideband characteristics (10 kHz–1 MHz). Due to the ultra-high dielectric constant at working temperature and the relationship between the strain and applied field intensity, the proposed antenna gets rid of the dependence on the poled materials and exhibits excellent communication properties beyond traditional mechanical antennas, which are experimentally demonstrated by a practical wireless communication system. Only using a single proposed mechanical antenna with 8 mm diameter and 3 mm thickness, the effective communication with a transmission distance of 200 m can be realized. This design offers a promising way of constructing mechanical antennas for long-wave communication.     

基于改进的GABP算法优化5G天线阵列

为了加快天线建模速度,针对现有天线设计软件天线参数优化速度过慢问题进行了建模研究。首先通过几种常用的启发式算法优化后的多层前馈（Back propagation,BP）神经网络对天线参数进行优化比较,并对其中最优的算法遗传算法优化BP（Genetic algorithm BP,GABP）神经网络算法进行深度改进。其次采用自适应算法和模拟退火算法优化算法对GABP进行优化。最终通过模拟试验验证出自适应GABP算法对于天线参数优化的误差最小。该研究为天线设计软件中天线优化方法提供了一种误差较小的新方法,拥有更高的预测准确度,拟合速度也大大提升。实验对比证明了该算法的可行性。     

Circularly polarized patch antenna with simultaneously wide frequency tuning range and high gain performance

A tunable circularly polarized square patch antenna with parasitic elements is designed for a wide frequency tuning range and high gain characteristics. The proposed antenna is constructed by one main patch and four semi-elliptic parasitic units. By loading four varactor diodes and adjusting their capacitance values, the tunable feature is performed to reallocate the corresponding working frequency. Moreover, the diagonal corners of the antenna are cut and loaded with varactor diodes, which provide the appropriate perturbation between the two orthogonality modes of the antenna, so as to ensure the circular polarization characteristic in the entire operating tuning band. The experimental results demonstrate that the reflection coefficient and axial ratio are less than −13 dB and 3 dB, respectively. The proposed antenna features a relatively wide continuously tuning range of 24% within 1.9-2.3 GHz and a stable gain of over 7 dBi with a radiation efficiency of above 85%.     

ESPAR array design for the UHF RFID wireless sensor communication system

In this paper, in order to improve the received signal strength (RSS) and signal quality, three arrays of electronically steerable parasitic array radiator (ESPAR) antennas are suggested for the ultra-high frequency (UHF) radio frequency identification (RFID) communication and sensing system applications. Instead of the single antenna, the array antennas have recently been widely used in many communication systems because of their peak gains, better radiation patterns, and higher radiation efficiency. Also, there are some important issues to use the antenna array like high data rates in wireless communication systems and to better understand the many targets or sensors. In this article, a wireless sensor network (WSN) is being investigated to overcome multipath fading and interference by antenna nulling technology that can be achieved through beam control ESPAR array antennas. The proposed ESPAR array antennas exhibit higher gains like 9.63, 10.2, and 12 dBi and proper radiation patterns from one array to another. Moreover, we investigate the mutual coupling effect on the performance of array antennas with different spacing (0.5λ, 0.75λ, λ) and configurations. It is found that the worst mutual coupling reduced by −28 to −34 dB for 2 × 2 array, −3 to −43 dB for 2 × 3 array, and finally −42 dB to −51 dB due to the antenna spacing from 0.5λ to λ. Thus, these suggested antennas could effectively be applied in the WSN communication systems, internet of things (IoT) networks, and massive wireless and backscatter communication systems.     

基于石墨烯超表面天线的太赫兹动态相位调控及波束扫描

太赫兹波频段介于毫米波和红外光之间,具有诸多优异特性,太赫兹天线更是太赫兹通信、雷达和成像等应用系统中的核心元器件。然而,目前报道的太赫兹天线均无法满足较大动态范围的相位扫描、高效率辐射和大偏转角度的需求。该文设计了 3 种石墨烯太赫兹天线,最小尺寸为 5 μm,并对其辐射效率和相位调控特性进行研究,进而提出具有双共振模式的石墨烯-金属太赫兹超表面天线,缓解了传统的基于单共振模式的相位动态调控范围和辐射效率之间的矛盾,实现了 0～360°的动态相位调控,且辐射效率高于 20%。该研究采用微加工工艺进行样品加工,通过改变栅极电压,在实验上获得了 1.03 THz 的太赫兹动态相位调控,反射率高于 23%,与仿真结果基本吻合。在此基础上,该文基于连续相位编码设计了石墨烯超表面相控阵天线,理论上实现了太赫兹波束在－25°～25°范围内的实时波束偏转。该文为解决超表面相控阵天线的相位动态调控范围小、辐射效率低等难题提供了新的研究思路。     

一种高功率微波有源相控阵天线单元设计

根据工程需要,本文提出了一种新型高功率微波有源相控阵天线单元,通过改造同轴波导变换器结构提升了功率容量和驻波特性,在同轴探针与阶梯波导之间引入方形金属块实现阻抗匹配,在波导末端添加过渡腔和匹配槽结构,并在喇叭段加入了单脊结构改变了波导阻抗,单脊伸出口径面降低了反射系数,进一步提升了功率容量。在X波段内VSWR小于2,带宽提升为1.25GHz,功率容量为33.24kW,比常规同轴波导变换器下喇叭天线功率容量提升了230％,7×7相控阵阵面可以实现1.62MW的发射功率,具备高功率微波发射能力。阵列可实现±30°圆锥扫描,满足高功率宽角度扫描的需求。     

基于铌酸锂薄膜的Y波导集成调制器设计

近年来,基于薄膜铌酸锂（TFLN）平台的高性能电光调制器以其小体积、低能量损耗等特点受到广泛关注。本文提出了一种新的具有垂直电极结构的Y波导铌酸锂薄膜电光调制器。研究了调制器的半波电压与缓冲层厚度之间的关系,优化了Y波导的设计参数,最后设计得到插入损耗<5 dB, 半波电压<1.5 V的高性能调制器。本文不仅为基于TFLN平台的小型化波导的设计和实现提供了思路,而且为制造高性能和多功能的电光调制器提供了实验依据。     

大规模MIMO系统中收发联合阈值天线选择算法

在大规模多输入多输出(massive MIMO)系统中使用天线选择算法可提高能效和系统吞吐量,然而适用于传统MIMO系统的天线选择算法具有高复杂度,很难用于massive MIMO系统。为优化天线选择算法,以算法复杂度和系统容量为优化目标,提出了收发联合阈值天线选择算法。该算法在发射端使用最大范数双向天线选择算法进行天线选择,在接收端使用分组maxvol算法并通过仿真实验结果的预设阈值进行天线选择。仿真实验表明,收发联合阈值天线选择算法在降低复杂度的同时可以提高系统容量,与递增天线选择算法相比,系统容量最多可提高52.2 bit/s/Hz。提出的天线选择算法可以满足不同天线相关度和信噪比的传输环境。     

Ku波段宽带高增益基片集成腔圆极化阵列天线北大核心CSCD

提出了一款应用于Ku波段的宽带高增益基片集成腔(Substrate Integrated Cavity,SIC)圆极化阵列天线。通过引入沿SIC口径面对角线放置的一对半月形寄生贴片和SIC底部馈电纵缝,使SIC中的TM_(211)和TM_(121)谐振模式幅值相等、相位相差90°,产生高增益圆极化辐射。同时,双寄生贴片还引入了一种背腔缝隙耦合振子圆极化辐射模式,扩宽了天线高增益圆极化辐射带宽。在此基础上,设计了一款2×2单元顺序旋转馈电的SIC圆极化阵列天线。阵列天线采用双层基片集成波导顺序相移馈电网络进行馈电,进一步增大了天线的圆极化带宽。综合考虑天线的-10 dB反射系数带宽、3 dB轴比带宽和3 dB增益带宽,测试结果表明,圆极化阵列天线的有效带宽为10.74-13.30 GHz(21.3%),在通带范围内最大增益为14.50 dBi。