介质谐振器天线研究进展

综述了介质谐振器天线技术三十多年来的主要研究进展.归纳了宽带/超宽带、圆/双极化、高阶模/高增益、毫米波设计及介质谐振器天线阵等方面的技术进展,也介绍了介质谐振器天线的特点与分析方法等.     

Dual band dielectric resonator antenna for wireless application

The proposed technique is an integration of a slot antenna and a dielectric resonator antenna (DRA). This is designed without compromising miniaturisation and efficiency. It is observed that the integration of slot and dielectric structure itself may be merged to achieve extremely wide bandwidth over which the antenna polarisation and radiation pattern are preserved. Here the effect of slot size on the radiation performance of the DRA is studied. The antenna structure is simulated using the CST software. The simulated results are presented and compared with the measured result. This DRA has a gain of 7.1 and 6.3?dBi at 5.7 and 8.1?GHz, respectively, its 10?dB return impedance bandwidth of nearly 4.5% and 5.5% at two resonating frequencies. A total of 98% efficiency has been achieved from the configuration. It is shown that the size of the slot can significantly affect the radiation properties of the DRA and there are good agreements between simulation and measured results.     

加载多层介质谐振器的宽带背腔缝隙天线设计

提出并设计了一种工作于X波段的新型宽带背腔缝隙天线,通过在缝隙外侧加载多层介质谐振器,有效扩展了天线带宽并显著提高了天线增益.设计的天线中心频率为10 GHz,-10 dB回波损耗带宽约为40％;带内增益5～9.5 dBi,比未加载多层介质谐振器的背腔缝隙天线提高2～3 dB.实测结果同设计结果基本吻合,有效验证了该设计的正确性.     

An X-band dielectric resonator antenna using a single elliptical shaped dielectric resonator

This paper presents design evolution of a single elliptical dielectric resonator antenna to achieve wide measured impedance band-width extending from 8.26 GHz to 12.15 GHz. Design evolved from a right circular cylindrical DRA by varying the dimension along the semi-minor axis and thereby resulting in an elliptical DRA that supports near similar field distribution over the X-band. This similar field variation is achieved by tuning the eccentricity of the elliptical geometry, the feed position as well as height of the DRA. A fabricated prototype is developed and measured results agree well with that obtained from simulation. Apart from wide impedance bandwidth, the observed pattern bandwidth is also similar.     

超宽频单极子陶瓷介质谐振器天线设计与仿真

设计了一种尺寸小、频带宽、结构简单的单板子陶瓷介质谐振器天线,该天线经由在单板子周围加一个环形的介质谐振器而成.该设计主要通过在环形谐振器中使用高介电常数的陶瓷材料降低天线的尺寸,利用环形谐振器与单板子谐振频率之间的耦合展宽天线的频带.利用仿真软件HFSS为该天线建立模型并进行优化仿真,得到了最佳的天线设计参数,优化所...     

一种新型介质谐振天线设计

采用双层磁电复合材料为基板,制作了一款小型(38 mm×38 mm)宽带介质谐振天线。为减小尺寸并提高带宽,天线采用了共面波导馈电及倒L形金属片加载。通过理论分析,给出了天线的等效电路,并对其进行了仿真分析。结果表明:在回波损耗S11<–10 dB时,该天线的工作频段为4.93~6.75 GHz,实现了宽频带的设计目的。     

2 200 MHz圆环形介质谐振器的研制

讨论了TE011谐振模式的圆环形介质谐振器的研制过程。固定ZnO添加量为质量分数1.00%,考察了WO3改性剂对(Zr0.8Sn0.2)TiO4微波陶瓷介电性能的影响。当w(WO3)为0.25%时,可得到εr为38.0、Q值大于5800(7GHz)、τf小于2.0×10–6/℃的瓷料。以该瓷料为原料制作谐振器,研究了制作工艺和支撑物高度对谐振器性能的影响。发现采用冷等静压成型工艺所制谐振器的Q值比采用干压成型工艺提高了4%。获得了谐振频率为2200MHz的高Q值、高功率、高稳定性圆环形介质谐振器,完全满足设计要求。     

一种基于介质谐振器的新型电磁超材料

文章设计了一种基于介质谐振器的新型混合左右手结构。该结构由工作在横电模式TE的介质谐振器嵌入到平行平板波导中组成。数值分析表明：工作频带为12 GHz～14 GHz,在13.15 GHz频率下相移为零。该结构在整个通带内插入损耗低于0.6 dB,同时具有极低的通带波纹,表现出了良好的传输特性。与普通的混合左右手结构相比,其结构简单,插入损耗较低,在高频时导体损耗也较低,在超级透镜、天线等领域具有很好的应用前景。     

960 MHz同轴介质谐振器滤波器的研制

研制了用四个高Q值介质同轴谐振器构成的带通滤波器,谐振器之间的耦合通过陶瓷基片上的电容实现,讨论了影响谐振器插入损耗的主要因素。结果表明,该四级式低损耗介质同轴谐振器滤波器中心频率f0为960MHz,插入损耗小于3.0dB,能满足设计要求。     

Effective modeling of metasurface-loaded circularly polarized dielectric resonator-based MIMO antenna for sub-6.0-GHz band using machine learning algorithms

In this article, a dual-port dielectric resonator antenna (DRA) is modeled using machine learning (ML) algorithms, that is, deep neural network (DNN), random forest, and XGBoost. The unique properties of the proposed article are as follows: (i) Two different diversity techniques, that is, pattern (with the help of metallic wall) and polarization (mirror image of the aperture), improve the isolation value between the ports; (ii) ML algorithms are used to optimize and predict the reflection coefficient as well as mutual coupling of the proposed antenna. The accuracy of ML algorithms is verified by using the HFSS EM simulator and experimental validation. Error is less than 1%–2% between the value predicted from ML algorithms and HFSS/experimental results. The proposed design is working well in between 2.4 and 4.02 GHz with a 3-dB axial ratio from 2.84 to 2.95 GHz. All these features make the radiator employable to the sub-6.0-GHz frequency band.     

Improvement of the stopband spurious window for a dual-mode dielectric resonator filter by new coupling technique

This paper presents a new design technique for two configurations of a dual-mode filter using a dielectric loaded cavity operating at 1.95 GHz. The dielectric puck in the proposed filter was floated in the middle of a cylindrical metal cavity with short circuits on the side walls and holes through the ceramic from the side face. These holes allowed the insertion of coupling probes which did not affect the unloaded quality factor or the spurious window. The inline structure fourth pole Chebyshev dual mode filter offers a 870 MHz suppression window while the planar configuration was 710 MHz from the resonance frequency and the operation bandwidth of 54 MHz. The volume reduction ratio was eight times larger compared with a coaxial filter of the same Q factor.     

基于Pocklington型积分方程式的有限间隙馈电实芯圆柱天线的分析

使用在馈电函数中含有磁流项的Poclington型积分方程式对实芯圆柱天线进行了分析．对于精确地求解存在于实芯圆柱天线外表面的电流分布时，该磁流项是必须考虑的．一个在馈电间隙上满足边缘条件的电场分布被使用，基于该电场分布的数值解析结果与试验结果，以及利用馈电间隙上的均匀电场分布所求解的结果进行了比较．     

任意形状天线罩的快速分析

将自适应积分算法与体积分方程相结合分析任意形状天线罩对天线辐射特性的影响。将任意形状的天线罩剖分成四面体，基于体积分方程的自适应积分快速算法求出天线罩上的感应电流，即可求出天线-天线罩系统的总场。自适应积分快速算法的应用提高了矩量法的计算速度，并大大缩减了需要的存储量，从而使该方法可用于分析电尺寸较大的天线罩.最后,分别计算了球形、锥形天线罩存在时理想电振子阵列的辐射方向图。     

介质覆盖导电球上缝隙天线的辐射

给出了用位函数方法推导介质覆盖导电球上缝隙天线辐射场严格解的过程.基于球Hankel函数加法定理,将基本磁流源激励的场展开为以球心为原点的球面波的叠加.利用球矢量波函数的定义及性质,提取出场的径向分量,将初级场分解为相对于径向的TE波和TM波,避免了复杂的矢量微分运算.在此基础上依据散射叠加原理,构造出各区域中场的一般表示形式,其中待定系数直接由球面分层介质中波的反射和透射规律给出.作为实际应用的例子,给出了介质覆盖导电球上均匀环缝问题的计算结果,并对结果进行了分析.     

Higher order mode impedances and cut-off frequencies of overmoded coaxial waveguides

Using both theoretical and experimental methods the critical geometrical ratios for effective higher order mode superposition in coaxial waveguides are identified for SDMA beam forming antenna applications. Higher order mode impedances are also important in the design of such antennas and a closed form expression for the power-voltage definition of impedance is derived together with estimates for the voltage-current and power-current forms. An industry standard finite element solver is used to confirm the accuracy of these formulations for a 60?mm radius overmoded coaxial waveguide. In the second part of the paper, the mode chart is used to design a coaxially fed, overmoded air-spaced coaxial waveguide “T” junction supporting the TEM, TE ₁₁ and TE ₂₁ modes. A Green's function based model of the input impedance of this junction establishes that the power-voltage characteristic impedance occurs naturally in calculations requiring absolute impedance values. Finally, this input impedance model, which includes higher order and evanescent mode propagation, is demonstrated to agree well with experimental data for this junction.     

Efficient computation of the 2-D Green's function for 1-D periodic line sources in planar multilayered media

Periodic Green's function (PGF) of an infinite 1-D periodic array of line sources in planar multilayered media is calculated by the use of the of the 3-level discrete complex image method (DCIM) together with the surface wave pole (SWP) extraction. The Ewald's method is then applied to accelerate the evaluation of the PGF. The recipe to choose the Ewald's splitting parameter is also given. It is shown that the Ewald's transformation needs a few terms to approximate the PGF with high accuracy. The SWP contributions, which are extracted before the DCIM application, are added to this approximation. The spatial domain surface wave pole contributions are observed to be highly oscillatory and converge to zero. The numerical results are provided to demonstrate the efficiency and the accuracy of the procedure followed.     

一种新型多层介质悬置微带线漏波特性的分析

提出了一种多层介质悬置微带线天线结构,以改善天线的频扫特性.分析表明:该结构不仅可以确保天线工作在效率较高的天线模工作区,而且它的泄漏常数在相当宽的范围内随频率都能平坦地变化.对频率扫描天线能保证当波束扫描时,可以保持一个相对稳定不畸变的辐射方向图.     

Controlling the conductance of single-molecule junctions with high spin filtering efficiency by intramolecular proton transfer

The pursuit of miniaturization of magnetic electronic components spurs intensive theoretical and experimental researches on designing molecule-scale magnetic devices. Controlling the transport properties is one of the most vital focuses for magnetic molecular devices. In this work, magnetic devices constructed by a single epindolidione (Epi) molecule (5,11-dihydrodibenzo[b,g][1,5]naphthyridine-6,12-dione) bridging two zigzag graphene nanoribbon (zGNR) electrodes are theoretically designed. The Epi molecule can be converted between the keto and enol forms, which is confirmed by first principle molecular dynamics method. The influences of intramolecular proton transfer and the bridging manner between the core molecule and zGNR electrodes on the magnetic transport properties are investigated. Spin-resolved current-voltage (I-V) curves show that both the keto and enol devices display remarkable spin filtering effect. However, the effect of intramolecular proton transfer on the electron transport properties depends on the bridging manner between the Epi molecule and zGNR electrodes. When the Epi molecule is connected to zGNR electrodes with 4,7-sites (A bridging manner), the electron transport properties of molecular junctions are hardly affected by the intramolecular proton transfer. On the contrary, the conductance of the molecular junctions is significantly modulated by the intramolecular proton transfer when the Epi molecule is connected to zGNR electrodes with 4,4′-sites (B bridging manner). Further analysis reveals that the high spin filtering effect originates from stronger coupling between spin-up edge electronic states of zGNR electrodes and states of the core molecule. With B bridging manner, the conjugation characteristics of the Epi molecule as well as the transmission pathway of tunneling electrons can be largely modulated by the intramolecular proton transfer. Our work proposes a feasible way to control the conductance of single-molecule junctions by taking advantage of intramolecular proton transfer.     

用有限元—边界积分法研究有限壁厚矩形波导窄边斜缝

本文应用有限元－边界积分法研究有限壁厚矩形波导窄边斜缝导纳特性，该方法首先用等效源原理及镜原理建立缝隙表面磁场积分方程，然后把它们代人到缝腔中场满足的变分公式中，最后用有限元法求得缝腔中及口面上的电场分布，求解把缝效为传输线上对称T型网络时缝并联导纳与缝倾斜角度及切割深度的关系，同时，观察了波导壁厚度及缝宽对谐振频率的影响。计算数据与最新发表的实验数据比较，结果基本一致。