一种新型类Vicsek分形多频天线的设计

在Vicsek结构的分形理论基础上进行了改进, 提出了一种具有良好空间填充性和自相似特性的新型类Vicsek分形天线, 并在接地板上引入缺陷地结构(Defected Ground Structure, DGS)来改善频率、抑制谐波, 得到了可以运用在无线局域网(Wireless Local Area Networks, WLAN)、全球微波互联接入(Worldwide Interoperability For Microwave Access, WiMAX)以及C波段卫星通信的四个频段.天线的谐振频率分别为2.45 GHz、3.46 GHz、5.8 GHz和7 GHz, 相应带宽为0.2 GHz(2.37~2.57 GHz)、0.49 GHz(3.2~3.69 GHz)、0.75 GHz (5.52~6.27 GHz)和0.56 GHz(6.68~7.24 GHz), 增益最高达到4.89 dB.天线的小尺寸及全向性辐射特性表明该天线能很好地满足便携式多频段移动设备的要求.     

一种基于零阶谐振的双频电小天线设计

提出利用复合左右手传输线结构的零阶谐振设计一款具有双频特性的电小天线。该电小天线主要由介质基板、地面、加载了交指电容的贴片、弯曲线电感与圆角矩形虚拟地组成,具有电小尺寸特性(电尺寸为0.75)。该天线有两个工作频段,频段1的中心频率为1.22 GHz,频段2的中心频率为2.78 GHz,对应的相对带宽分别为3.28%和27.34%,同时覆盖了GPS L2 (1220 MHz)与WiMAX (2500～2700 MHz)两个通信频段。天线在两个工作频段内均具有良好的辐射特性,频段1和频段2的平均峰值增益分别为1.0 dBi和1.72 dBi,平均辐射效率分别为53.12%和74.07%。最终对所设计的天线进行实物加工和测试,测试结果与仿真结果吻合良好。     

基于PCB的三频高回波损耗印制单极子天线

该文设计了一种印制于玻璃纤维环氧树脂基板的单极子天线,天线通过同轴线馈电,借助HFSS 13.0软件仿真可工作于3个频段,中心频率分别为2.45GHz、3.5GHz和5.55GHz,带宽分别约为400MHz、550MHz和800 MHz。在2.45GHz时回波损耗高达45dB。分析了参考地高度H1、辐射单元宽度W和辐射单元长度R2对天线参数S_(11)的影响。通过网络分析仪测量实物与软件仿真结果进行比较,二者基本吻合,具有一定的合理性。     

基于寄生振子的多频印刷天线

RFID技术近年来发展迅猛,但是各国使用的频段却不统一。为了增强RFID系统的兼容性,本文设计一款应用于RFID标签的3频印刷天线。采用加载寄生振子实现天线的3频工作。使用ADS仿真软件对本文所设计的天线进行了仿真研究,结果表明反射损耗小于-15dB时天线的工作带宽分别为782.5～851.1MHz,919.3～995.5MHz,2.446～2.577GHz,满足设计要求。这3个频段分别覆盖了中国划分的两个RFID频段以及国际通用的2.45GHz频段。     

基于加载寄生带的双频天线设计

文中提出了一种双频印刷天线设计方法,覆盖2.4 GHz和5.2 GHz频段。该天线通过在偶极子天线振臂旁平行放置寄生单元,降低天线在高频段的输入阻抗(通常输入阻抗远大于50Ω),从而实现良好的阻抗匹配,在主谐振频段外产生新的寄生谐振频点,达到双频段工作的目的。为了验证所提出的天线设计方案,建立了仿真模型,并加工了天线实物。通过仿真分析和实测发现,改变寄生金属单元的位置和尺寸只影响高频段谐振频点,几乎不影响低频段谐振频点,而偶极子天线尺寸的改变只影响低频段谐振频点,不影响高频段谐振频点。文中设计的天线具有双频段相互独立特性,因此天线的两个谐振频段可根据需求独立设计。     

新型双频全向Alford环微带天线

基于无线通信系统对极化分集的应用需求,提出一种新型双频水平极化全向Alford环天线。该天线由2个环形辐射结构构成,外环辐射结构包含4个微带偶极子阵列,谐振频率为2.45 GHz;同时新增耦合圆环内辐射结构,谐振频率为5.225 GHz。实测结果表明,该天线在802.11b (2.40～2.48 GHz)和802.11a (5.15～5.35 GHz)频率范围内S11优于-10 dB,其中在2.45 GHz和5.225 GHz的S11分别达到-17.9 dB和-27.2 dB。由于具备良好的水平极化全向辐射特性,该天线可作为极化分集天线单元应用于无线局域网(WLAN)多输入多输出(MIMO)系统中。     

RFID圆环缝隙天线设计以及环境影响测试

为了满足2.45GHz射频识别系统工作的需求,所设计的2.45GHz圆环缝隙标签天线的性能指标为:在驻波比小于1.5的条件下,工作带宽约为300MHz(2.19~2.49GHz);天线增益为3.31dBi;天线尺寸满足RFID系统应用需求.本文给出了该标签天线的实测结果,与理论结果吻合良好.论文给出周边塑料瓶水、玻璃瓶水、金属罐头瓶在不同位置时对天线匹配特性影响的测量,结果表明,塑料瓶水和玻璃瓶水对天线匹配性能的影响类似,当周围物体距离天线小于2.5cm时,天线的谐振频率将发生偏移.金属罐头瓶距离天线小于0.3cm将导致天线无法工作,当所有物体距离天线的位置超过2.5cm时,天线可以正常工作.     

一种容性馈电宽带微带天线的设计与分析

通过使用容性馈电贴片、短路面和短路探针,设计并分析了一种宽带微带天线.该天线的相对带宽达到47.3% (S11＜-10 dB),频段覆盖1.6～2.59 GHz.工作频段内的3个谐振频率形成了足够大的带宽.仿真结果表明,容性馈电贴片对辐射贴片表面电流的耦合效应会影响天线的性能,通过调节短路探针的位置可以获得稳定的辐射方向图.该天线的工作频段和特性符合无线通信系统应用的要求.     

具有双陷波特性的超宽带平面天线设计

设计了一种带有2个陷波频段的超宽带天线。天线的缝隙和馈电枝节采用相反的梯形结构,以实现较好的阻抗匹配。通过在宽缝隙中增加2个线形枝节和1个"E"形结构,使得天线在3.0 GHz~3.9 GHz和5 GHz~6 GHz 2个频段内出现频率阻断。根据天线的阻抗曲线,给出等效谐振电路并对陷波产生的原理进行了分析。最后对天线的远场辐射特性进行分析和阐述,测试结果良好,达到了陷波超宽带天线频率阻断的效果。     

加载超表面的双频紧凑高隔离阵列天线设计

为了减小极小距离多输入多输出(multiple-input multiple-output, MIMO)天线之间的相互耦合,设计了一种极紧凑的高隔离度的双频MIMO贴片天线,谐振频率分别为2.45 GHz和3.5 GHz。该MIMO天线由两个对称的双层U型槽贴片天线组成,其中边与边的距离为0.5 mm(0.004λ0,λ0为中心频率2.45 GHz时的自由空间波长)。利用不同宽度的双层金属线切割对作为超表面单元,该超表面体积紧凑,可以显著降低天线单元之间的相互耦合。仿真和测量结果表明：在天线工作频段2.4～2.5 GHz和3.4～3.6 GHz范围内,单元间的隔离度可以提高到30 dB以上,并且两个天线端口阻抗匹配良好,同时在低频段的总效率提高了9%左右;两天线间的包络相关系数(envelop correlation coefficient,ECC)在2.45 GHz时由0.33降到0.01,在3.5 GHz时由0.09降到0.006,所设计天线具有良好的辐射性能。     

Dual band microstrip patch antenna array loaded with split ring resonators and via holes

Reduction in antenna size by using multi-band radiators play a vital role in the miniaturization of present world wireless handheld devices, as dual band behaviour of the antennas result in the integration of more than one communication standard in a single system and thus, saving the installation space required for separate antennas. In this context, this communication presents a shorted-pin dual band metamaterial inspired microstrip patch antenna array. Under the unloaded conditions, the traditional patch antenna array resonates at 5.8 GHz with gain of 9.8 dBi and bandwidth of 540 MHz. However, when each patch of this traditional antenna array is loaded with split ring resonator (SRR) and a metallic via hole is introduced in the patch, the same antenna array produces an additional resonant frequency in IEEE 802.11b/g/n 2.45 GHz Wi-Fi band with bandwidth and gain of 290 MHz and 5.6 dBi, respectively, while the initial resonant frequency (i.e. 5.8 GHz) gets shifted to IEEE 802.11ac 5 GHz Wi-Fi band, providing the gain and bandwidth of 11.4 dBi and 510 MHz, respectively. The proposed antenna array has been fabricated, and the measured results are presented to validate the proposed array. Moreover, the equivalent circuit of the proposed antenna array has been designed and analyzed to validate the simulated, measured and theoretical results. Attainment of dual band characteristics by incorporating the metamaterial with single band traditional patch antenna array makes this structure novel, as this has been achieved without any extra hardware cost, size and loss of structural planarity. Also, both the frequency bands of this proposed metamaterial inspired antenna array possess considerable gain and bandwidth.     

Design of a patch antenna with square ring-shaped-coupled ground for on-/off body communication

Bio-telemetry is an advanced area of research that enables the transmission of biomedical parameters from human body to external monitoring device. Wearable antennas showing robust performance are attaining attention for RF bio-telemetry. A square ring-shaped ground antenna with a truncated patch is investigated for dual mode, on-body and off-body communication. The proposed antenna structure is analysed and optimised on a multi-layered flat tissue phantom. Proposed design resonates at 2.6 GHz with |S11| ?22 dB and at 5.2 GHz with |S11| ?35 dB on the phantom gel. Wide bandwidth of 520 MHz (2.33–2.85 GHz) and 620 MHz (4.78–5.4 GHz) efficiently covers ISM, LTE and WLAN bands and enables the antenna to withstand frequency detuning due to different body postures. Antenna shows maximum radiation efficiency of 15% at 2.45 GHz band when placed close to the tissue. Low specific absorption rate (SAR) value of 0.459/0.523/0.303 W/Kg at 2.45/2.6/5.2 GHz ensures the tissue safety.     

Miniaturization of Dual‐Band PIFA for Wireless LAN Communication

In this letter, a simple method for reducing the size of a dual‐band planar inverted‐F antenna (PIFA) is described. This method is based on a coupling capacitor connected in parallel to the PIFA feed conductor. The proposed antenna occupies a small ground clearance of 10 mm×5 mm and is able to provide ?10‐dB impedance bandwidths of 120 MHz and 760 MHz for 2.45‐GHz and 5.5‐GHz wireless local area network applications, respectively. The measured antenna efficiencies are 71.8% and 73.6%, averaged over the 2.45‐GHz and 5.5‐GHz frequency bands, respectively.     

低剖面可承载UHF/L双频共口径圆极化定向天线

机/车载多体制通信、测控、探测等多无线系统并存,天线林立,天线间耦合干扰严重,同时与高速机/车薄壁外壳共形的天线还需具有较强承载能力.本文设计了一种适于车壳共形的低剖面可承载双频共口径定向圆极化缝隙天线.天线主体采用开口缝隙的形式来实现天线的小型化和宽带设计,利用微带线来进行耦合馈电.通过在低频天线中心开槽嵌入高频天线...     

RFID基站天线与系统应用

针对RFID系统的应用特点,不同的应用领域所采用的天线也不同,应根据不同的读写范围、工作距离和天线的安装使用要求,来设计不同的基站天线方式。设计了工作在915MHz频段八木天线、螺旋天线、微带阵天线,并给出了仿真与测试结果。     

Printed compact dual band antenna for 2.4 and 5 GHz ISM band applications

A printed compact dipole antenna for dual ISM band (2.44 and 5 GHz) is presented. The proposed antenna fed by using a 50 /spl Omega/ coaxial line occupies a volume of 15/spl times/40/spl times/1 mm/sup 3/ (FR-4, permittivity 4.6). The impedance bandwidth for 10 dB return loss is about 400 MHz (from 2170 to 2570 MHz) at 2.4 GHz band and over 2300 MHz (from 4690 to beyond 7000 MHz) at 5 GHz band. The measured radiation gains range from 1.20 to 1.41 dBi at 2.4 GHz band and from 2.25 to 3.44 dBi at 5 GHz band, respectively.     

Wire-antenna designs using genetic algorithms

There is a large class of electromagnetic radiators designated as wire antennas. As a rule, an inductive process is used to design these antennas. Either an integral equation is formulated or a simulator is used that gives the current distributions on the wires of the antenna, from which the electromagnetic properties of the antenna can then be determined. Once the antenna properties are known, the parameters are optimized, using guides such as intuition, experience, simplified equations, or empirical studies. However, using an electromagnetics simulator in conjunction with a genetic algorithm (GA), it is possible to design an antenna using a completely deductive approach: the desired electromagnetic properties of the antenna are specified, and the wire configuration that most closely produces these results is then synthesized by the algorithm. In this paper, we describe four antennas designed using GAs. The first is a monopole, loaded with a modified folded dipole that was designed to radiate uniform power over the hemisphere at a frequency of 1.6 GHz. The second antenna consists of seven wires, the locations and lengths of which are determined by the GA alone, that radiates waves with right-hand-circular polarization at elevation angles above 10°, also at 1.6 GHz. The last two antennas are modified Yagis. One is designed for a broad frequency band and very low sidelobes at a center frequency of 235 MHz. The other is designed for high gain at a single frequency of 432 MHz. We have built and tested these antennas     

Asymmetrical mirror imaged monopole antenna with modified ground structure for DBDP radiations

ABSTRACT

In this article, asymmetrical mirror-imaged monopole antenna comprises a rectangular patch with tuneable stub and supported with modified ground structure (MGS) is investigated. The proposed antenna is characterised for dual band dual polarised (DBDP) radiations and can operate at 2.45 GHz for Wi-Fi and WLAN systems (2.4–2.485 GHz) and 5.45 GHz for WLAN band (WLAN band: 5.2–5.8 GHz) with the corresponding polarisations. A rectangular patch integrated with tuneable stub and a pair of asymmetrical inverted L-shaped slots positioned at ground plane is responsible for circularly polarised higher band; while a parasitic patch is created due to slotting of a mirror-imaged stub from the extended ground plane which is accountable for lower frequency band. The fabricated prototype shows that the measured Impedance bandwidths (VSWR < 2) are 350 and 1770 MHz for lower and higher frequency bands, respectively. The measured axial ratio bandwidth (AR < 3 dB) is yielded as 1450 MHz centred at 5.44 GHz for higher frequency band. The peak gains are measured as 4.3 and 4.15 dB for lower and higher frequency band, respectively. For the prototype antenna, substantial 3-dB beamwidth is found along with good cross polarisation suppression.     

Design of a compact planar wide band antenna family

A new family of compact planar wide band antennas is proposed. These simple and planar antennas have stable omnidirectional patterns and flat gain in the whole of bandwidth. Five types of these antennas are designed and simulated to clarify the ability of these introduced antenna family. Also, one of these antennas is fabricated and tested. The simulation and the measurement results are in good agreement. The measurement results show that this antenna works between 1.91 and 5.25 GHz (93.3% bandwidth) and it has a very compact dimensions. Also, the antenna analysis results show that the antenna center frequency and bandwidth can easily controlled by changing the scale factor and section factor, respectively. Finally, the antennas comparison results with the references verify the capability and power of them.