Novel dual-band antenna for multi-mode GNSS applications

A novel dual-band antenna is proposed for mitigating the multi-path interference in the global navigation satellite system（GNSS） applications. The radiation patches consist of a shortedannular-ring reduced-surface-wave（SAR-RSW） element and an inverted-shorted-annular-ring reduced-surface-wave（ISAR-RSW）element. One key feature of the design is the proximity-coupled probe feeds to increase impedance bandwidth. The other is the defected ground structure band rejection filters to suppress the interaction effect between the SAR-RSW and the ISAR-RSW elements. In addition, trans-directional couplers are used to obtain tight coupling. Measurement results indicate that the antenna has a larger than 10 d B return loss bandwidth and a less than 3 d B axial-ratio（AR） bandwidth in the range of（1.164 – 1.255） GHz and（1.552 – 1.610） GHz. The gain of the passive antenna in the whole operating band is more than 7 d Bi.

Embedded Dual band Cylindrical Dielectric Resonator Antenna

A compact dual band antenna made of high dielectric constant substrate is studied. Embedding a higher dielectric cylindrical inside the substrate host cylindrical enhances the dual band behaviour. The first part displays the characteristics of single CRDA as return loss, bandwidth and radiation pattern, then, the second part describes the aim of using an antenna, composed by the arrangement of two cylindrical resonators in which the smallest is inserted in the largest, to lead dual-frequency behaviour, and achieve a dual-band antenna. The proposed antennas are investigated using Finite Element Method (FEM), the impedance matching dual band definition and covers the Ultra High Frequency band (UHF).

Experimental Study of Stacked Rectangular Microstrip Antenna for Dual-Band

A dual-band characteristic of stacked rectangular microstrip antenna is experimentally studied. It is a probe fed antenna for impedance matching with 50Ω coaxial cable. This antenna works well in the frequency range (2.86 to 4.63 GHz). It is basically a low cost, light weight medium gain antenna, which is used for mobile communication. The variations of the length and width (1mm) of the stacked rectangular patch antenna have been done. And it is found dual resonance with increasing lower resonance frequency and almost constant upper resonance frequency with increases of the length & width of rectangular microstrip antenna. The input impedance and VSWR, return loss have been measured with the help of Network analyzer.

Aperture Coupled Microstrip Antenna for Dual-Band

This paper presents air gap aperture coupled microstrip antenna for dual-band operation over the frequency range of (2.9 to 6.0 GHz). This antenna differs from any other microstrip antenna with their feeding structure of the radiating patch element. Input signal couples to the radiating patch trough the aperture that exists on the ground plane of microstrip feed line. The dual-band achieved by variation of air gap [2 mm to 6 mm] between single patch antenna and aper-ture coupled microstrip antenna. The main advantage of this type antenna is increased the bandwidth of the antenna as compared to a single layered patch antenna. The two resonant frequencies can vary over a wide frequency range and the input impedance is easily matched for both frequencies. The obtain ratios of resonance frequencies are variable from 2.1 GHz to 1.1 GHz with increasing the air gap between single patch and aperture coupled microstrip antenna. The measured return loss [–14 dB] exhibits an impedance bandwidth of 35%. The input impedance and VSWR return loss have been measured with the help of Network analyzer.

Analysis of Rectangular Notch Antenna for Dual-Band Operation

In this paper a design of single layer rectangular notch microstrip antenna for dual-band is proposed and experimentally investigated. This antenna is excited by microstrip line. Direct microstrip coupling with proper matching transformer has been used. Design is made for optimized notch dimension for two resonant frequencies. These resonance frequencies change with the variation in length and width of the notch. The input impedance and VSWR have been measured with the help of Network analyzer. It is found that the input impedance and VSWR depends variation in length and width of the notch microstrip antenna.

Resonant Length Formulations for Dual Band Slot Cut Equilateral Triangular Microstrip Antennas

The dual band equilateral triangular microstrip antennas are realized by cutting the slots of either quarter wave or half wave in length, inside the patch. In this design, however these simpler approximations of slot length against the frequency do not give closer results for different slot lengths and there positions inside the patch. In this paper, the modal variations of slot cut patch antennas over wide frequency range are studied. It is observed that the slot does not introduce any mode but reduces the higher order mode resonance frequency of the patch and along with the fundamental mode realizes dual band response. The formulations of the resonant length for the mode introduce by the slots in these antennas are proposed. The resonance frequencies calculated using proposed formulations agree well with the simulated results with an error of less than 5%.

Electromagnetic coupling reduction in dual-band microstrip antenna array using ultra-compact single-negative electric metamaterials for MIMO application

In this paper, an ultra-compact single negative（SNG） electric waveguided metamaterial（WG-MTM） is first investigated and used to reduce the mutual coupling in E ＆ H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only λ_0/33.6 ×λ_0/15.1（where λ_0 is the wavelength at 1.86 GHz in free space）. Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 d B reductions in the H plane, 8.5/7.9 d B reductions in the E plane at1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35 λ_0（where λ_0 is the wavelength at 1.86 GHz in free space）. The proposed strategy is used for the first time to reduce the mutual coupling in E ＆ H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.

Dual Band MIMO Antenna Composed of Two Low Profile Unbalanced Fed Inverted L Antennas for Wireless Communications

A low profile dual-band multiple-input-multiple-output (MIMO) antenna system is proposed. The proposed MIMO antenna consists of two low profile unbalanced fed inverted L antennas with parasitic elements to resonate at 2.45 GHz and 5 GHz. The structure is uncomplicated by locating two ultra low profile inverted L antennas on the finite conducting plane. The proposed MIMO antenna is numerically and experimentally analyzed. When the size of conducting plane is 55 mm by 55 mm and the height of antenna is 9 mm, the directive gain of 4.11 dBi and the S11 bandwidth of 5.71% are achieved for lower frequency of 2.45 GHz. At the upper frequency of 5 GHz, the directive gain of 8.22 dBi and the S11 bandwidth of 6% are obtained. The proposed antenna has good diversity gain, shown by the correlation coefficient becomes less than 0.005 at the frequency of 2.45 GHz and 5 GHz band when the distance between inverted L elements is 41 mm. A good agreement between calculated and measured results is obtained. The results show that the weak mutual coupling of the proposed antenna and this feature enables it to cover the required bandwidths for WLAN operation at the 2.4 GHz band and 5 GHz band.

Multiband LTE-A/WWAN Antenna for a Tablet

In this paper, an internal multiband antenna is proposed for LTE-A/WWAN wireless applications in tablet computer. The proposed antenna is configured to have two branch radiators. These two branch radiators are a U-shaped driven monopole and a nonuniform wrapped inverted U-shaped monopole. The impedance bandwidths across dual operating bands are 89.7 MHz and 4185 MHz at the LTE-A/WWAN bands. Various techniques, such as branching and parasitic element are used to enhance the antenna’s bandwidth, the matching, and the size of the proposed antenna. The antenna is presented on an area of 50 × 15 mm2. Experimental results of this antenna show nearly omni-directional coverage and stable gain variation across the LTE-A/WWAN bands.

一种新型双频双圆极化复合微带天线设计

针对空间微波能量收集的应用场景,提出了一种微带线行波激励的双端口双频双圆极化复合微带天线。该天线由一个工作在低频段的微带圆环和一个工作在高频段的微带圆片复合而成,分别由两种不同的正交十字缝隙耦合馈电,采用微带线级联依次相差90°顺序旋转四馈电实现圆极化,通过对称性结构设计,分别从两个不同端口输入获得双圆极化性能。实验结果表明:在880~960 MHz和1.85~2.45 GHz频带内S11<−10 dB,阻抗相对带宽分别为8.7%和30%;在885~920 MHz和1.86~2.43 GHz频带内轴比小于3 dB,圆极化相对带宽分别为4%和29%;天线的方向性在工作频段内良好,在低频段增益达到5.4 dB,在高频段增益达到7.7 dB。该天线结构紧凑且加工简单,为双端口双频双圆极化天线的研究与设计提供了新思路。

可用于WLAN的双频MIMO天线设计

设计了一款可用于WLAN的双频MIMO天线。天线的正面为L型单极子,背面为金属接地板。通过在接地板上加载耦合枝节使天线具有双频特性。同时,为了天线的小型化,对耦合枝节进行了弯折处理,减小天线尺寸。在两个天线单元之间加载T型寄生枝节和刻蚀矩形缝隙来提高天线的隔离度。使用电磁仿真软件和矢量网络分析仪对天线进行仿真和实测,结果表明:天线的工作频段为2.4~2.55 GHz和5.1~6.3 GHz,覆盖了WLAN的频段,同时在低频段内隔离度高于19 dB,高频段内隔离度高于25 dB。此外,天线的包络相关系数小于0.01且具有全向辐射特性。天线整体性能较好,可以满足WLAN的需求。

加载人工磁导体的双频柔性可穿戴天线

该文研究了一种加载人工磁导体(AMC)的双频柔性可穿戴天线,天线的谐振频率为3.5 GHz和5.8 GHz。天线由双频单极子天线和4×4阵列的双频人工磁导体构成,均采用柔性材料作为介质基板。天线尺寸为0.70λ_(0)×0.70λ_(0)×0.05λ_(0)(λ_(0)为3.5 GHz时的自由空间波长)。人工磁导体的介质基板为3层结构,增加了相位响应,使用双环开槽结构延长电流路径长度,实现了双频的宽带同相位反射。人工磁导体的引入有效降低天线的背向辐射,从而降低比吸收率(SAR),同时提高天线的增益。仿真结果表明,该天线性能受结构变形和人体载荷的影响较小。在工作频段内天线的阻抗带宽分别为7.5%和4.0%;峰值增益分别为7.86 dBi和8.06 dBi。在3.5 GHz和5.8 GHz的比吸收率分别为0.2 W/kg和0.06 W/kg,均小于美国联邦通信委员会标准。为了验证仿真结果,对天线进行加工测试,实测与仿真结果基本一致。实验结果表明,加载人工磁导体的天线具有良好的鲁棒性和增益以及较低的比吸收率,适用于可穿戴无线通信系统。

基于SIR多模谐振器的双频滤波天线设计

本文设计了一款基于多模谐振器的双频滤波天线,其滤波谐振器采用阶跃阻抗谐振(SIR)来进行枝节末端分流结构小型化设计,可以灵活控制两个频段的中心频率。与加载开路短截线的矩形单极子天线相比,集成设计构成滤波天线,其工作在ISM频段(工业、科学和医学频段),两通带外引入3个辐射零点,实现了工作频段的高选择性,增益分别为1.60 dBi和4.03 dBi。测试结果表明,该天线反射系数、峰值增益和辐射方向图与设计仿真结果吻合良好,具有较好的滤波和辐射特性。

一种用于射频识别阅读器的双频宽带圆极化天线

该文设计了一种紧凑的用作射频识别(RFID)阅读器的双频宽带圆极化天线。天线由弯折处理的矩形贴片、L形贴片和三角形地板构成,通过微带线进行馈电。两个辐射贴片分别独立控制高低两个频段,其轴比带宽也可独立调整,三角形地板可以使横向电流和纵向电流发生变化,从而改变横向电流和纵向电流的比值大小,实现圆极化性能。天线尺寸为0.92λ_(0)×0.92λ_(0)×0.0064λ_(0)(λ_(0)为2.40 GHz时的自由空间波长)。测试结果表明在超高频(UHF)频段该天线实现了49%(0.77~1.27 GHz)的阻抗带宽和46%(0.84~1.34 GHz)的轴比带宽,在无线局域网(WLAN)频段实现了47.5%(1.54~2.50 GHz)的阻抗带宽和24.2%(1.96~2.50 GHz)的轴比带宽,可以完整覆盖UHF和WLAN两个频段,具有良好的辐射特性。与其他双频圆极化天线相比,该天线整体结构紧凑、设计简单、避免了使用复杂的馈电网络,且具有较宽的3 dB轴比带宽。

基于诱导磁的惠更斯超表面与毫米波透镜天线应用

超表面因强大的电磁操控能力,在现代无线通信及毫米波雷达等领域展现出巨大的应用潜力。在结构极简的超表面上实现尽可能丰富的电磁功能是工程界孜孜以求的目标。以诱导磁机制为出发点,对结构极简的惠更斯超表面进行了系统性研究,并对其在毫米波透镜天线中的潜在应用进行了全面综述。诱导磁机制能够利用单层印制电路板(Printed Circuit Board,PCB)基板的双层金属图案激发磁谐振,进而激发惠更斯谐振,在电磁波调控方面突破了传统频率选择表面的移相限制,并为在结构极简的超表面上实现高效的透射波操控铺平了道路。惠更斯超表面的潜在应用包括单极化、双极化、双频带、低剖面和透/反双功能超透镜天线设计。由于可以使用单层PCB基板制备,制备容易、成本低廉,基于诱导磁的惠更斯超表面对于未来天线工程有着重要的应用价值。

二维/三维可调纸基超材料天线

为满足移动通信系统对多频段、小型化天线的设计需求,结合超材料的结构优势,基于折纸技术设计了一种二维/三维可调双波段纸基超材料天线。为了说明纸基天线易加工、低成本、易携带等特点,分别将导电银浆涂覆在不同纸基材料上制备了天线实物样机。仿真和测试结果表明,在二维和三维状态下,天线分别工作在2.45 GHz和1.40 GHz频率处,且通过调节内环折叠角度可实现工作频段的调控。此外,分别研究了二维和三维天线的辐射方向图。二维天线的主辐射方向与天线所在平面垂直,而三维天线的主辐射方向受内环折叠角度调控。所设计的纸基超材料天线为实现工作频段可切换的天线设计提供了新思路,在便携式移动终端、多波段通信等领域具有广阔的应用前景。

双陷波可重构特性的蓝牙超宽带天线设计

提出了一种具有双陷波可重构特性的蓝牙/超宽带(UWB)天线。天线由削顶圆形单极子天线加载1/4波长圆弧枝节组成。在圆形贴片上刻蚀2个半波长圆形缝隙,实现WLAN(5.125~5.825 GHz)和ITU(8.025~8.4 GHz)频段的陷波功能。通过控制安装在陷波结构中PIN二极管的工作状态,能够实现陷波的可重构特性。测试与仿真结果表明:在天线工作频段2.39~2.52 GHz和2.92~12 GHz内,天线辐射性能良好,峰值增益达到5.2 dBi。可广泛应用在各种通信系统。

基于火烈鸟搜索算法的天线优化设计

在天线优化设计领域,传统电磁软件采用参数扫描方法,计算量大且效率低。针对此问题,文中提出了一种基于火烈鸟搜索算法和HFSS(High Frequency Structural Simulator)联合优化的设计方法,并通过MATLAB和HFSS联合仿真完成实现。在MATLAB中编写天线设计和仿真代码,生成VBS(Visual Basic Script)脚本供HFSS调用,HFSS将电磁仿真的结果返回给适应度函数计算。由火烈鸟搜索算法根据适应度值进行粒子寻优,直至找出最优结果,确定最优天线尺寸参数。文中联合仿真设计在迭代23次时寻得最优尺寸参数,使得优化后的天线在两个工作频段对应的适应度值由-483.37 dB优化到-771.15 dB。仿真结果表明,所提算法具有较强寻优能力,收敛速度块,可有效提升天线优化设计的效率。