顶加载分形光子晶体太赫兹波段天线设计

针对太赫兹设备对于太赫兹波段天线的性能要求,创造性地将顶加载技术、分形结构、光子晶体结构、偶极子天线、聚对苯二甲酸乙二酯(PET)薄膜基质相结合,设计了一款顶加载分形光子晶体太赫兹波段天线,制作了天线样品,对天线的回波损耗和方向图特性分别进行了仿真和实测,详细讨论了介质基板参数变化对天线性能的影响。仿真和测试结果表明,该款天线工作中心频率在1 THz附近,回波损耗最小值小于-20 dB,绝对工作带宽大于0.1 THz,相对工作带宽大于10%。该款天线尺寸小、辐射性能稳定、工作带宽大,在太赫兹波段领域具有广阔的应用前景。     

基于分形理论对天线的讨论

利用分形理论设计出的分形天线和分形天线阵,具有小巧、灵活、轻便、同时还具有多频带、宽频带和“自加载”特性,它们存在多种多样形式,在军事工业和通信行业将有很大的发展潜力。     

正方形嵌套分形多频印刷对称振子天线

设计了一类具有正方形嵌套结构的新型分形多频对称振子天线.振子由一系列相似的正方形单元嵌套组成.天线能够同时工作于多个频率,这些频率涵盖了WLAN系统所要求的2.4 GHz/5.2 GHz/5.8 GHz三个频率,采用三维电磁仿真软件CST MWS(R)软件进行了仿真研究,得到了平衡微带线馈电的对称振子天线的模型.制作了...     

一种基于分形结构的超宽带天线研究

基于微带天线和分形天线的基本理论,采用正方形和圆形交替的方法设计了用于超宽带（UWB）通信的分形天线。利用电磁仿真软件CST软件对所设计的天线进行仿真、优化,并分析了影响天线阻抗特性和辐射特性的关键参数。从仿真实验结果可以看出,所设计的天线有较好的全向辐射特性和宽的阻抗带宽,能够满足超宽带通信需求。     

第五代移动通信系统三重复合分形天线设计

针对第五代移动通信系统对天线的性能要求,将谢尔宾斯基分形结构、康托尔分形结构、分形折线雪花结构相融合,设计了一款三重复合分形天线,对天线性能进行了仿真分析,制作了天线样品并对其进行了测试。仿真和测试结果表明,该款天线回波损耗最小值为-21.84 d B,绝对工作带宽达到2.047 GHz,相对工作带宽达到48.51%,天线具有全向辐射特性。利用渐变介电常数介质基板设计了改进型天线结构,有效地展宽了天线的工作频段。该款天线能够完全覆盖第五代移动通信的三个候选频段,具有尺寸小、回波损耗低、工作带宽大等优点,在第五代移动通信系统中具有广阔的应用前景。     

一种共面波导馈电的分形缝隙宽带天线

结合共面波导馈电和分形天线的优点,设计了一种共面波导馈电的正六边形分形缝隙天线。选择正六边形分形缝隙结构,采用渐变的共面波导馈电,不仅拓宽了阻抗带宽,而且实现了天线的小型化。通过计算测量,对天线的阻抗特性、增益和方向图进行了研究。实验表明,此分形缝隙天线的阻抗带宽达到89%,并且在整个工作频段内具有良好的辐射方向特性。     

类Minkowski分形天线的分析与设计

为了实现一款天线在ISM2.4G(2.4～2.483 5 GHz)、Bluetooth、GPS、WLAN(2.4～2.48 GHz)等多频段同时工作,设计了基于分形理论的类Minkowski分形微带天线,方案中对原有的Minkowski分形结构和接地板进行改进。通过仿真分析与优化设计使得天线尺寸缩减至90 mm×71 mm×1.6 mm,谐振频率为2 GHz,工作在0.93 GHz～3.02 GHz频段,相对带宽为105.82%,最大增益可达1.89 dB。最终天线能够进行良好的阻抗匹配,对天线带宽进行展宽,达到了超宽频带天线的要求。     

基于三维集成的小型化Ku波段收发组件

基于硅基三维集成模块和印制板(Printed Circuit Board,PCB)混压工艺,设计了一种小型化Ku波段收发组件,并对其原理方案和具体实现进行了介绍。该收发组件整体电路采用三维集成架构实现,射频及中频芯片和其外围电路集成于硅基三维集成模块中,外部电路板采用射频与低频混压印制板,模块和印制板通过球栅阵列(Ball Grid Array, BGA)互联。通过对信号过渡结构进行优化设计,降低了信号传输损耗,提升了通道间隔离度。电路测试表明,组件在工作频带内满足通道间幅度一致性、带内平坦度、噪声系数等指标要求,且符合组件小型化、高集成度、高一致性、高可生产性的现实需求。     

一种433MHz小型化螺旋形印刷天线的设计

采用微带线在介质基片上模仿螺旋天线的走线形式,设计了一种433 MHz小型化螺旋形印刷天线,减小了天线的结构尺寸。采用仿真软件HFSS对天线的主要结构参数进行分析和优化,推导出了天线的最佳结构参数,并通过加载无源集总元件的方法改进了天线的阻抗性能。对回波损耗、增益进行了研究,结果表明:S(1,1)<-10 dB的有效带宽为3.4 MHz(431.5 MHz~434.9 MHz),在433 MHz谐振频点处的S11为-24 dB,有效增益为-4.14 dB。     

一种宽带天线的研究与设计*

为了满足宽带通信的需求,利用U形单极子天线和两个U形寄生辐射元的方法,设计了一种共面波导馈电的宽带天线,其阻抗带宽达到85%。所设计的天线印刷在尺寸为20 mm×30 mm×1.6 mm、介电常数为265的聚四氟乙烯介质基板上。为了满足无线局域网（WLAN）和全球互联微波接入（WiMAX）的工作需要,抑制不需要的信号,在U形单极子辐射元之间插入一条调谐微带线,产生一个陷波特性,使所设计的天线满足WLAN、WiMAX和低端UWB通信需求。利用高频结构仿真软件HFSS对影响天线性能的主要参数进行仿真、分析和优化,得到天线的优化尺寸,并对优化的天线进行制造和测试。实验结果表明,该天线比传统微带贴片天线性能有了较大的提高,证明了利用共面波导馈电和寄生技术设计宽带天线的可行性和有效性。     

A novel dual‐wideband inscribed hexagonal fractal slotted microstrip antenna for C‐ and X‐band applications

This paper presents a novel geometry of inscribed hexagonal slotted microstrip antenna for dual‐band performance where the fractal iteration has been made by introducing concentric slots in the patch geometry. Using the equivalence principle and cavity model, the basic geometry of the hexagonal slotted patch is analyzed, and the resonant frequencies of different modes of the patch are computed. Higher‐order modes of the patch antenna are used to obtain dual band. Good performance in terms of the reflection coefficient is proved with the help of parametric analysis. The antenna geometry is simulated using electromagnetic simulation software based on the finite‐element method. The prototype of this antenna is fabricated and tested. The practical results match with the simulated results. The proposed antenna provides improved average gain. The peak values of measured gain are found to be 5.238 and 7.023 dBi—in the two bands 5.85 to 6.48 GHz and 7.28 to 8.63 GHz, respectively. Stable radiation patterns with good average gain make the proposed antenna appropriate for long‐range transmission. Furthermore, low profile and low cost make this antenna suitable for the future point‐to‐point high‐speed wireless communication applications.     

Implementation of hybrid fractal metamaterial inspired frequency band reconfigurable multiband antenna for wireless applications

In the present paper authors propose the design and analysis of a hepta band metamaterial inspired octagonal shape antenna using hybrid fractals for wireless applications. Multiband characteristics in the designed antenna is accomplished by introducing of slotted octagonal shape radiating part with hybrid fractal form of Moore curve and Koch curve and two SRR cells. The frequency band reconfigurability is obtained with aid of PIN diodes placed inside the strips connected between Moore curve (fused with centered Koch curve) and feedline. During ON mode of PIN diode antenna operates at seven microwave frequency S‐band WiMAX (3.4~3.69 GHz—IEEE 802.16e)/Lower C‐band terrestrial fixed and mobile broadband application (4.25~4.76 GHz)/C‐band WLAN (5.15~5.35/5.75~5.825 GHz—IEEE 802.11a] (5.4~5.9 GHz)/Lower X‐band Earth exploration‐satellite service ITU region 2 (7.9~8.4 GHz)/Upper X‐band Amateur satellite operating band (10.45~10.50 GHz)/Lower Ku‐band Radar communication application (13.25~13.75 GHz)/Middle Ku‐band Geostationary satellite service (14.2~14.5 GHz) covering various wireless applications. Proposed design exhibit hexa/hepta band features during OFF/ON mode of PIN diode. An acceptable gain, stable radiation characteristics, and good impedance matching are observed at all the resonant frequencies of the proposed structure.     

Investigations on modified rectangular fractal curve shaped dielectric resonator antenna

In this article, a modified fractal rectangular curve (FRC)‐shaped dielectric resonator antennas (DRA) with two different functionalities is reported. These antennas are split in the middle into two halves and are excited by a coaxial probe. In first configuration, the fractal geometry is used to achieve wide bandwidth from 3.5 to 5.0 GHz covering the body area network frequencies as well as the IEEE 802.11a WLAN frequencies. The average peak gain within the band is about 7 dBi. The second investigation involves miniaturization of rectangular DRA by using FRC along the cross‐sectional boundary. By this, a DRA at 3.2 GHz could be realized using second iteration of modified rectangular curve fractal geometry resulting in a 50% size reduction by maintaining same radiation characteristics. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Giuseppe Peano and Cantor set fractals based miniaturized hybrid fractal antenna for biomedical applications using artificial neural network and firefly algorithm

In this research paper, Giuseppe Peano and Cantor set fractals based miniaturized hybrid fractal antenna (GCHFA) is proposed that operates for biomedical applications. The proposed GCHFA is designed by merging Giuseppe Peano and Cantor set fractals that help in achieving better performance characteristics as well as miniaturization. Firefly algorithm (FA) has been employed to optimize the feed position of the designed antenna. The substrate material selected for the proposed GCHFA is low‐cost, commercially available FR4 epoxy whose thickness is 1.6 mm and relative permittivity is 4.4. A data set of 65 GCHFAs with different geometrical parameters is generated for the realization of two different bioinspired approaches. For the performance evaluation of fabricated prototype, vector network analyzer is used. The experimentally observed resonant frequencies are 2.4400 and 5.8115 GHz, and at these resonant frequencies, S (1,1) < ?10 dB. The designed antenna is suitable for Industrial, Scientific, and Medical bands of biomedical applications. Moreover, the behavior of the proposed GCHFA is nearly omnidirectional. A comparative study of three different artificial neural networks (ANNs) is also done to evaluate the most suitable ANN type for the analysis of proposed GCHFA. The optimized, simulated, and experimental results depict that they are closely matched.     

High isolation two‐port compact MIMO fractal antenna with Wi‐Max and X‐band suppression characteristics

This article features about an ultra‐wideband (UWB)‐multiple‐input multiple‐output (MIMO) antenna that exhibits the potentials of good port isolation and dual‐band suppression. The proposed antenna model consists of a unique fractal‐shaped radiating patch, a common ground interface leading to the incorporation of an intuitive approach; parasitic inverted neutralization stubs, which is located at the central co‐ordinate axis system, protruded vertically, where its extension is twisted with a motive of enhancing the port isolation. In addition to that, contiguous notches are implemented to achieve band‐notching at WiMAX (3.35‐4.45 GHz) and X‐band (9‐10 GHz). The total electrical area of UWB MIMO antenna is 0.179(λ₀)² at 2.25 GHz. To rationalize the counterparts of MIMO and band‐notching, diversity performance is studied through the electromagnetic (EM) solver and the corresponding circuit analysis is pursued through a electronic design automation (EDA) solver. The prototype has been fabricated, measured, and agreed well with the simulated results. The feasibility of proposed antenna model is considered to be quite optimum, with due consideration of its outcomes from applications point‐of‐view.     

Dual‐band circularly polarized aperture‐coupled stack antenna with fractal patch for WLAN and WiMAX applications

This article presents a novel circular polarized (CP) aperture coupled stack antenna for wireless local area network and worldwide interoperability for microwave access dual‐band systems. The compact stack antenna consisted of square fractal patch, aperture couple, feed line and the perturbation. The square patch is constructed with the complementary Minkowski‐island‐based fractal geometry. By way of adjusting the relevant parameters, we can obtain the dual‐band responses at 3.5 and 5.25 GHz respectively. The CP of each band are presented. The measured 10 dB return loss impedance bandwidth are 270 MHz (7.5%) for 3.5 GHz band and 450 MHz (8.6%) for 5.25 GHz band. The 3 dB axial ratio bandwidths for each bands are 1.4 and 0.76%, the polarization of radiation patterns are both left‐hand CP, and the antenna power gain are 2.84–3.1 and 0.16–2.2, dBic respectively. The proposed antenna is successfully simulated and measured with frequency responses, radiation patterns and current distributions. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:130–138, 2014.     

A novel compact self‐similar fractal UWB MIMO antenna

A novel compact self‐similar fractal ultra‐wideband (UWB) multiple‐input‐multiple‐output (MIMO) antenna is presented. This fractal geometry is designed by using iterated function system (IFS). Self‐similar fractal geometry is used here to achieve miniaturization and wideband performance. The self‐similarity dimension of proposed fractal geometry is 1.79, which is a fractional dimension. The antenna consists of two novel self‐similar fractal monopole‐antenna elements and their metallic area is minimized by 29.68% at second iteration. A ground stub of T‐shape with vertical slot enhances isolation and impedance bandwidth of proposed MIMO antenna. This antenna has a compact dimension of 24 × 32 mm² and impedance bandwidth (S₁₁ < ?10 dB) of 9.4 GHz ranging from 3.1 to 12.5 GHz with an isolation better than 16 dB. The various diversity performance parameters are also determined. There is good agreement between measured and simulated results, which confirms that the proposed antenna is acceptable for UWB applications.     

A miniaturized circularly polarized implantable RFID antenna for biomedical applications

A miniaturized circularly polarized implantable antenna operating at ultrahigh frequency band (902‐928 MHz) for radio frequency identification biomedical monitoring is first presented and experimentally validated in this article. The proposed antenna features a compact volume with a dimension of π × (6)² × 1.27 mm³ by employing an extended ring with meandered lines for size reduction. Moreover, adjusting the length of symmetrical meandered lines can introduce two orthogonal modes, which makes for good performance of circular polarization. Superb impedance matching between the chip and tag antenna is well implemented by applying a modified T‐match stub. In the simulation, the antenna achieves a ?10‐dB impedance bandwidth of 42 MHz (902‐944 MHz) and 3‐dB axial‐ratio bandwidth is 53 MHz (892‐945 MHz). Finally, the specific absorption rate is also calculated for human safety and the measured reading range reaches the maximum distance of about 87 cm.