High gain and circularly polarized substrate integrated waveguide cavity antenna array based on metasurface

Two substrate integrated waveguide (SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38% (4.05 GHz-5.95 GHz) and AR bandwidth of 24.9% (4.4 GHz-5.65 GHz). The bandwidth of the high gain antenna can reach 42.7% (3.95 GHz-6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.     

A multi-frequency circularly polarized metasurface antenna array based on quarter-mode substrate integrated waveguide for sub-6 applications

A miniaturized multi-frequency circularly polarized array is designed in this paper. The antenna array is composed of three independent sub-arrays employing modified quarter-mode substrate ntegrated aveguide (QMSIW) to achieve three circularly polarized frequency bands. By introducing strip-slot, the impedance bandwidth of the antenna array is broadened while the dimension is decreased by 75% to realize miniaturization. Meanwhile, metasurface causes the impedance bandwidth of the sub-array to be further enhanced. Moreover, the metal vias are employed in the antenna array design to further achieve miniaturization. The antenna array is manufactured and measured to verify the design. Both the measured and simulated results display that the array achieves the impedance bandwidths of 10%, 11.7%, and 14.8% and axial ratio bandwidths of 8.8%, 8.0%, and 8.5% at 2.5, 3.5, and 4.8 GHz, respectively. The gain is stable in the operating band within an uncertainty of 0.7 dBi. The whole dimension is 0.92λ×0.63λ×0.04λ, where λ₀ is the wavelength at the lowest resonant frequency. Furthermore, the simple structure and miniaturization provides great convenience in sub-6 applications.     

基于串口转WiFi的物联网终端远程控制实现方法

随着物联网技术的高速发展,对同一无线局域网内的设备进行控制时,存在传输距离短、可移动性差等缺点。针对此问题,提出了一种物联网终端远程控制的实现方法,采用串口转WiFi模块,通过Socket模式下的透传机制,传统的串口设备能够无线接入到互网络中基于MQTT消息传输协议的服务器上,完成数据的接收和发送,从而使终端设备突破无线通信距离的限制,达到数据交互和远程控制的目的。实验结果表明该方法正确、可靠,可广泛应用于智能家居、工业控制等领域。     

紧凑长轴向色散光谱共焦镜头

为提高和扩大光谱共焦位移传感器的测量精度和测量范围,并解决像方测量大数值孔径和物方光纤小数值孔径匹配下镜头过长的问题,设计一种紧凑型长轴向色散光谱共焦镜头。色散镜头用5个球面镜片,在工作波长450～700 nm内轴向色散范围达3.5 mm,波长和焦移线性拟合相关系数为0.97,像方数值孔径为0.48,光学长度为135 mm。在相同的镜头参数下,该色散镜头的轴向长度相比普通色散镜头减少了约35%。最后利用设计的色散镜头搭建光谱共焦位移测量系统,并进行性能评估实验。实验结果表明,该系统的最大测量标准差为0.05μm,最大平均绝对误差为0.04μm,实际轴向分辨率优于0.5μm,对被测物的最大测量角约为28.5°。     

微信服务平台的设计及在办公中的应用

由于电脑办公对地点、设备等要求带来的不便,所以对微信办公进行了研究,提出了基于微信公众平台的高校办公流程。采用Linux php mysql作为开发平台,利用微信公众平台开放接口实现整个过程。以校园信息化服务系统为例,阐述了该系统的办公流程、设计方法、核心技术,达到普通用户可通过微信客户端向学校各部门提出建议,管理员通过微信绑定身份后可实现信息分类、回复等办公操作的目的。借助微信公众平台实现智能终端办公,有助于实时交互、提高办公效率、简化办公操作,与此同时,也对此类微信办公开发具有借鉴意义。