基于耦合谐振去耦网络的双频近距天线解耦

提出了一种基于耦合谐振的双频去耦网络,并将其应用于一对二元双频近距单极子天线的解耦中。对去耦网络满足的去耦条件和匹配条件进行了推导;将网络以双频耦合谐振器的结构加以实现,提取了该结构的等效电路;基于去耦网络,设计了一副工作于WLAN 2.45/5.25 GHz的二元双频近距单极子天线,天线阵元边缘间的距离为2.45 GHz时的0.0735λ0和5.25 GHz时的0.1575λ0（λ0为自由空间工作波长）。对未解耦天线和解耦后天线进行了仿真和测试,结果表明,通过加载去耦网络,2.45 GHz和5.25 GHz处的隔离度分别提高了24.52 d B和26.57 d B,且在两个频段内阻抗匹配良好、总的效率提高、通道容量增大。提出的去耦网络适用性强,结构紧凑且解耦高效,可应用于无线终端MIMO技术中。

加载X型条带的微带天线阵解耦

在设计天线阵的过程中,阵元间的互耦往往是难以避免的一大问题。本文提出了一种新型的X型条带用于5元一维E面微带天线阵的解耦,天线阵的阵元间距仅为0.450?。仿真结果显示,通过加载该X型条带,与参考天线阵相比,所设计的天线阵具备较强的解耦能力,各端口的阻抗匹配良好,相邻与不相邻阵元间的互耦均有效减弱,同时各天线的辐射方向图显著改善,扫描盲点消除。该结构在相控阵天线和大规模天线阵中有很强的应用前景。

超构表面设计及其应用

超构表面作为二维形式的超构材料,在分界面处可以对透射、反射电磁波产生特定的相位分布,因此能够灵活调控电磁波前。超构表面的低剖面二维平面结构,在电磁调控领域具有广泛的应用前景,一系列的超构表面应用应运而生。主要介绍了超构表面的设计发展以及其应用,主要包括天线应用、RCS减缩、特殊波束、有源超构表面等4个方面。首先,在天线应用方面,超构表面可用于实现高增益透镜和极化转换功能;其次,从吸波型和散射调控型2种不同工作机理的角度介绍了应用于RCS减缩的超构表面;然后,针对特殊波束,主要介绍了超构表面在涡旋波束和全息成像中的应用;最后,从加载不同有源原件的角度分析有源超构表面的发展,并未来超构表面发展值得深入研究的方向。

基于多路去耦网络的对跖Vivaldi天线阵解耦

该文提出一种基于多路去耦网络解耦宽带天线阵的设计方法。首先,通过节点分析法推导通用多路去耦网络模型的解耦条件和阻抗匹配条件,形成一般设计方法。其次,将多路去耦网络应用至2元对跖Vivaldi天线阵,以低频段为设计基点,依据设计原理得到多路去耦网络的结构参数,增加渐变传输线拓展去耦带宽。实测结果表明,阵列在3.34~13 GHz(3.89:1)的工作频段内隔离度均高于20 dB,与耦合阵相比隔离带宽增加58.8%,且辐射性能得到改善。最后,在1维8元阵列中验证多路去耦网络的有效性,阵列在带内隔离度均高于20 dB,且在±60°的扫描范围内具有良好的辐射性能。所设计的多路去耦网络具有通用性、结构简单和宽带解耦能力,在相控阵天线和大规模通信系统中具有极大的应用前景。

基于超构表面的高效宽带交叉极化转换器设计

基于近年来利用超构表面在调控电磁波极化状态方面的热度,应用超构表面设计了一种适用于微波频段的新型极化转换器,可以在比较宽的带宽内,将入射的线极化波高效地转换为其交叉极化的反射波,在四个频点附近转换效率甚至达到100%。在整个工作频带内,仿真和测试结果基本吻合,仿真得到极化转换效率高于90%,频带宽度为7.88-20.70 GHz,相对带宽达到了89.7%。理论上给出了极化转换器的设计原理,仿真确定了转换器谐振点的位置,分析了极化转换器工作的物理原理,实验验证了极化转换器的效果。所设计的极化转换超构表面在极化选择控制方面有重要应用。

无载波超宽带引信组合脉冲功率谱快速拟合方法

为满足无载波超宽带(UWB)引信高斯组合脉冲波形设计需求,该文提出一种基于正交化寻基(OBS)的快速功率谱拟合方法。根据脉冲形成因子的取值范围构造多个候选的高斯脉冲函数,在通过最大化互信息实现功率谱设计的基础上,以循环迭代的方法进行功率谱拟合,每次迭代都对候选高斯脉冲函数进行施密特正交化,并通过内积计算快速地找出尚未被选取的候选高斯脉冲函数中与残留幅度频谱最匹配的一个,最终,根据选定高斯脉冲函数与它们正交化函数之间的矩阵关系确定加权系数,从而得到组合波形,使得拟合出的功率谱与设计功率谱之间达到较好相似性。通过仿真,验证了该文所提方法的有效性,及其相对于粒子群迭代算法的高效性。

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 d Bi.The whole dimension is 0.92λ×0.63λ×0.04λ,whereλ_(0) is the wavelength at the lowest resonant frequency.Furthermore,the simple structure and miniaturization provides great convenience in sub-6 applications.