自相似扩展分形网屏的透射场分析

本文使用Ｓｉｅｒｐｉｎｓｋｉ填料作为例子，分析了自相似扩展分形网屏弗琅荷费近轴区的透射场，发现该透射场同样具有自相似特性。     

一种新型加载Sierpinski垫片天线的设计

提出一种新型分形结构加载的Sierpinski垫片天线。该天线采用新型加载技术并充分利用了此新型结构的空间自填充能力。结果表明,此新型分形结构加载的Sierpinski垫片天线比Koch分形加载更能缩减天线的尺寸,并且能降低谐振频率,具有宽频带特性,可以实现Sierpinski分形天线的小型化、多频段特性。     

Shorted fractal Sierpinski monopole antenna

This paper describes novel configurations of shorted fractal Sierpinski gasket antenna. The antenna uses half the structure of a conventional Sierpinski gasket antenna and is folded over to be parallel to the ground plane, to form an element similar to that of the inverted L antenna. A quasi log periodic resonance behavior is obtained with a shorting pin placed at the far end of the antenna. Several configurations are shown and a design using two shorting pins which improves the bandwidth at the fundamental band is also demonstrated.     

Fractal volume antennas

The fractal volume antenna concept is introduced in order to increase the degree of design freedom associated with fractal antenna elements and hence improve their input matching characteristics. Practical examples are given involving the Sierpinski triangular gasket monopole and a novel Sierpinski carpet gasket microstrip antenna. The scope for further optimisation and some manufacturing aspects are noted     

Size-reduction of pre-fractal Sierpinski monopole antenna

A method for decreasing the height of a fractal Sierpinski monopole is presented. The method is based on the construction of a wire Sierpinski monopole with a Koch island loop as initiator. This initiator changes the perimeter of the gasket while preserving the multiband behaviour and the radiation power pattern characteristics of the conventional Sierpinski gasket.     

Shorted fractal Sierpinski monopole antenna

A novel configuration of a shorted fractal Sierpinski gasket antenna is proposed. Using only half the structure of a conventional Sierpinski gasket, the antenna is folded over to be parallel to the ground plane, to form an element that is, in some ways, similar to the inverted L antenna. A shorting pin is then placed at the far end of the antenna. A quasi log periodic resonance behaviour is observed     

Dual band FSS with fractal elements

Experimental and computed results of a frequency selective surface (FSS) based on a certain type of fractal element are presented. The fractal element is a two iteration Sierpinski gasket dipole. Owing to the dual band behaviour of the two iteration Sierpinski gasket dipole, two stopbands are exhibited within the operating frequency band. This behaviour is obtained by arraying one simple element in a single layer frequency selective surface (FSS)     

Analysis of Modified Square Sierpinski Gasket fractal microstrip antenna for Wireless communications

In this paper, the slot loaded microstrip antenna has been developed with Sierpinski gasket technique. The proposed Modified Square Sierpinski Gasket (MSSG) fractal antenna involves a square patch utilizing Sierpinski gasket (triangular) structure. Four triangular slots are loaded at each iteration. The structure is then simulated using commercially available Ansoft HFSS simulator. The multi-band operation has been achieved by the proposed antenna at 15.915 GHz, 20.045 GHz, 23.077 GHz, 27.77 GHz frequencies with −20 dB, −25 dB, −22 dB, −28 dB return loss respectively which works well for Ku (12–18 GHz) and K (18–27 GHz) band. The consistent result is obtained after simulation and the validity of fabricated design is checked by the measured result. The designed antenna is an attractive candidate for applications like wireless multi-band communication systems.     

Iterative network model to predict the behaviour of a Sierpinskifractal network [antennas]

A simple, fast, numerical model to predict the input parameters of a network with the topology of the Sierpinski gasket fractal shape, is introduced. The usefulness of the model is shown through comparison with experimental results for the SPK90 patch antenna     

Modeling of fractal antennas

Results on the numerical analysis of the Sierpinski and Koch fractal antennas are presented. It is shown that self-similarity of fractal structures affects electromagnetic properties of antenna structures created on the basis of these fractals. It is demonstrated that the Sierpinski and Koch fractal antennas are multiband structures; therefore, these antennas can be used for the development of radar and telecommunications systems. A technique is proposed for generation of an irregular determinate fractal structure that can be used for the development of a frequency-independent fractal antenna.     

Compact CPW-fed Sierpinski fractal monopole antenna

A novel compact and uniplanar CPW-fed Sierpinski fractal monopole antenna is presented. A fractal radiating element represents the fourth iteration of the Sierpinski gasket with scale factor /spl delta/=1.5. The antenna is printed on a single layer dielectric substrate and fed by 50 /spl Omega/ CPW transmission line. The multiband operation of the planar fractal structure is confirmed experimentally.     

Multiband multiple ring monopole antennas

This paper proposes two novel designs of a multiband antenna using multiple rings. The first design consists of a set of self-similar circular rings. This is an alternative to the recently reported triangular fractal Sierpinski gasket monopole antenna, and comparison is made to this and the circular disk monopole antenna. The second design is realized by varying the shape of the circular structure to an elliptical one. Larger bandwidth and improved patterns are achieved. In comparison to the circular disk, improved radiation pattern control at higher operating bands, due to the discrete structure of the multiple rings, is shown by numerical and experimental results. The bandwidth is significantly larger than the Fractal Sierpinski gasket and Parany monopole.     

一种顶部加载型Sierpinski垫片天线的分析

将分形几何应用于天线设计可以产生具有多频段或小型化特征的分形天线。传统的多频段分形天线Sierpinski垫片天线由于是有限次迭代生成的,它存在截取效应低端谐振频率比值几乎是其几何相似性因子的两倍,从而限制了其实际应用。本文针对一种小型化的加载型Sierpinski垫片天线进行了有效的研究,证实了加载对降低天线高端谐振频率的有效性,同时分析了结构参数对其工作频段的影响并提出了增大天线张角的方式以进一步小型化天线。     

Multi-circular loop monopole antenna

A novel multi-band multiple circular loop monopole antenna is presented. The three outer loops have a size ratio of 2 while the feed monopole is a disc, resulting in a quasi-log periodic performance. A method for controlling the radiation pattern, which gives better results than the circular disc monopole at higher operating frequencies, is presented. The proposed antenna performance is also compared with that of the fractal Sierpinski gasket monopole     

Analysis of a modified Sierpinski gasket monopole antenna printed on dual band wireless devices

The traditional Sierpinski gasket monopole antenna is well known for its multiband behavior, but it cannot be printed on the circuit board of a portable wireless device due to the limited space availability. In this paper a modified Sierpinski gasket monopole antenna is presented that possesses a small physical size, high efficiency and the ability to allocate both the 2.4 and 5.2 GHz Industrial Scientific and Medical bands without the need of a matching network. The modified element respects the multiband behavior of the gasket since the input impedance characteristics of the upper bands maintain their symmetry. Several modification techniques are proposed making the monopole very flexible in terms of band allocation and fine-tuning. The dimensions of the ground plane are also proven to play a significant role on the operational bandwidth of the antenna system.     

新型RF-MEMS可重构分形天线

设计了一种新型的集成RF-MEMS开关的混合分形可重构天线,该天线为加载了1阶Koch曲线的1阶Sierpinski三角垫片结构.仿真结果表明:所设计的天线在MEMS开关全闭合和全断开的状态下分别具有多个不同的工作频带.详细地分析了天线的重构特性,按照仿真模型在高阻硅片上运用微电子工艺制作出了天线样品.对样品进行了测试,最后比较和分析了测试结果.     

Perturbed Sierpinski multiband fractal antenna with improved feeding technique

This paper describes the multiband behavior of a series of perturbed fractal Sierpinski gasket antennas. Sierpinski gaskets, with periodic ratios of 0.5, 0.65, and 0.75 were fabricated and tested. Two methods are presented that improve the inherently poor input impedance match of the antenna with a 50 /spl Omega/ port. Theoretical simulation is used to give an insight into the field distribution of the antenna as the perturbing ratio varies. Different properties and merits of the antenna due to perturbation were noted. These improved feeding methods will allow further flexibility to the application of these multiband antennas.     

Fractal Geometries of Complementary Split-Ring Resonators

Complementary split-ring resonators (CSRRs) are typically used as negative-permittivity particles in microstrip left-handed structures. In this paper, novel CSRRs that use a square Sierpinski fractal curve are proposed and studied in detail. It is shown that the application of fractal geometries results in significant miniaturization of the metamaterial unit cell in comparison with conventional and equivalent meander structures. Multiple fractal CSRRs are also analyzed. The influence of different geometrical parameters and the order of the fractal curve on the performances are investigated, as well as the efficiency of excitation of the particles. When used in the design of left-handed transmission lines, fractal complementary split rings improve frequency selectivity in the upper transition band when compared to other nonfractal topologies.     

Sierpinski分形天线特性分析

Sierpinski分形天线的结构具有自相似性,从而天线具有良好的多频带特性。文中主要研究了Sierpinski分形天线频带位置随天线张角和比例因子变化的一般规律,并简要的分析了Sierpinski分形天线阵,绘出了其远场方向图,讨论了其低副瓣特性。     

改进型Sierpinski分形微带天线仿真

将HFSS高频仿真软件对不同张角下的二阶Sierpinski分形天线进行仿真,得到不同情况下的回波损耗参数和方向图。Sierpinski分形天线具有多频段的特性,由其自相似分形结构决定。在一定角度下的二阶Sierpinski分形天线具有双频特性,可以广泛应用于卫星通信和移动通信。