Fractal Antennas

In this work the performance and analysis of a miniaturized dual band hybrid Koch curve dipole antenna is introduced. The proposed antenna design, analysis and characterization has been performed using the Method of moments (MoM) technique. The radiation characteristics, reflection coefficient, VSWR and Input Impedance of the proposed antenna were described and simulated using 4NEC2 software package and MATLAB R2008a. Also the gain of the proposed antenna is calculated and described in the three planes: XY-plane, XZ-plane, and YZ-plane, where the antenna is placed in the XY-plane. The proposed antenna can be operated in GSM frequency band and WIMAX frequency band. In order to quantify the advantages provided by the hybrid nature, the proposed study performs a comparison of the proposed antenna with the quadratic Koch dipole fractal antenna and triangular Koch dipole fractal antenna.

A compact fractal monopole planar antenna with size of 30× 25 mm2 is proposed for ultra wide band (UWB) application. The proposed antenna is designed by combination of Giusepe Peano and Sierpinski Carpet fractal geometries. The feed circuit is a microstrip line with a matching section over a semi-elliptical ground plane. The proposed antenna has an omnidirectional radiation pattern and good gain. The simulated results of return loss, gain and radiation patterns are presented and discussed.

A new form of modified microstrip-line feed fractal patch antenna is proposed for wideband application. The fractal shape is based on triangular, modified with circle and iteration of self similar design. The -10 dB return loss (VSWR 2:1) impedance bandwidth is 80% ranging from 2.4-5.6 GHz . The EM characteristics of the antenna are presented by the current distribution. Proposed antenna maintained good radiation pattern with gain. Detailed design steps and study of different parameter are presented in this paper.

A printed monopole antenna with microstrip-fed Sierpinski fractal geometry for dual wideband application is presented. The operating bands are adjusted with the design of modified Sierpinski triangle (radiating patch), ground plane and scale factor used to create a fractal shape. The simulated 10 dB (VSWR 2:1) reflection bandwidth for first resonant frequency is 60% (1.47 GHz2.7 GHz). It covers GPS, DCS1800, PCS-1800, UMTS, IMT-2000, WiBRO (Wireless Broadband Internet Services) and WLAN bands. For second resonant frequency the band width is 8% (4.991HHz-5.4 GHz) and covers 5.2 GHz WLAN (802.11/ a). The radiation characteristics and gain of the modified Sierpinski fractal antenna are also presented and discussed.

A new form of modified microstrip-line feed fractal patch antenna is proposed for wideband application. The fractal shape is based on triangular, modified with circle and iteration of self similar design. The -10 dB return loss (VSWR 2:1) impedance bandwidth is 80% ranging from 2.4-5.6 GHz . The EM characteristics of the antenna are presented by the current distribution. Proposed antenna maintained good radiation pattern with gain. Detailed design steps and study of different parameter are presented in this paper.

Four iterations of a Coplanar Waveguide (CPW)-Fed KOCH SNOWFLAKE fractal antenna are studied. Increasing the number of iterations allow us obtaining a simple and miniaturized antenna with good performances, operating for Ultra Wide Band (UWB) applications. The proposed antennas are a good solution for the 3.7-4.2GHZ C-Band, the 5.15-5.82 Wireless Local Area Network (WLAN), and for the 5GHZ Worldwide Interoperability for Microwave Access system (WIMAX) applications. The simulation was performed in FEKO 6.3.

This letter presents the design, simulation, and measurement of a novel multiband fractal circular antenna for wireless applications. In the antenna design, we used a circular antenna where we took a ring. Then, in the first iteration, we added a new ring divided into two of the same size. For the second iteration, we added a ring of the same size after dividing it into two halves. In the third iteration, we added the third ring of the same size after dividing it into four. Due to the resonator defection, we were able to reduce the size of the starting antenna from 60×70×2 mm 3 to 50×50×1.6 mm 3 , to get the frequency of 2.48 GHz, and we generated new bandwidths with a high gain that reaches 5.02 dB. The proposed antenna radiation characteristics, such as the impedance matching, the gain, the radiation pattern, and the surface current distribution are presented and discussed. We find that the simulated and measured results are in acceptable agreement and affirm the good performance of the proposed antenna. The results obtained affirm that the proposed fractal antenna is a better candidate for integration into wireless communication circuits.

Now-a-days in modern wireless telecommunication systems, antennas with smaller size, greater efficiency, and wider bandwidths are in great demand. To fulfill these requirements fractal concept in antennas are very popular which provides compactness and can generate multiple frequencies and also enhances its bandwidth. So this paper presents design and simulation of Square shaped fractal antenna using HFSS 15.0 software. This Square shaped fractal antenna is designed for 3 GHz resonant frequency using FR-4 epoxy as substrate. This antenna incorporates a pin diode integrated on its surface to change the current distribution path which changes the resonance frequency depending on the state of the pin diode i.e. on its on and off position thus making it a frequency reconfigurable antenna. Also the simulated results are presented in this paper. I. INTRODUCTION During last few years there is increase in need of antennas in wireless communication systems which is smaller in size, shows multiband characteristics and should be low-cost too. Recently much research has been done on antennas based on fractal geometries because reports have shown that it enhances antenna efficiency, shows multi-band characteristics and also because these antennas are smaller in size. Basically fractal antennas are nothing but a single elementary shape that shows multiple iterations making it a complex shape that possess a self-similarity in their geometrical structure. Various researches have proposed fractal antennas of different shapes such as Sierpinski fractal antenna, tree-shaped fractal antenna, and some other types including snowflake fractal antenna and Koch fractal antenna. Though these antennas reduce the size and cost, but in case of communication system many applications are used that works at different frequency band hence a single fractal antenna cannot be used to serve the purpose of the whole communication system. To resolve this issue researchers have proposed reconfigurable antennas. These antennas resonate at different frequencies at different time by using switches therefore reduces the cost and overall size of the system. In this paper a reconfigurable fractal antenna is designed which has square shape as its elementary shape and shows three iterations thus making it a complex structure patch. To make it reconfigurable a pin diode is used as switch at the feeding line to show multi band behavior.

In this paper, a new method based on strip line structures is presented for characterization of metamaterials. The proposed method is suitable for characterization of all types of artificial structures including Single Negative (SNG) and Double Negative (DNG) media. The new method has the advantages of easy fabrication and low cost, when compared to free space or the waveguide methods. Furthermore, it has the advantage of extracting both permittivity, e, and permeability, μ, with a single measurement, when compared to microstrip line method.

This paper presents the design of novel conformal fractal loop antennas proposed for the rapidly developing RF identification (RFID) wireless technology. Two antennas, based on Koch and Hilbert fractal geometries, are designed and optimized for 0.953 GHz RFID band. Key design requirement has been maximizing the antenna gain and directivity that results in increasing the read range of RFID system.

In this paper, a probe-fed self-affine fractal antenna, which has a novel configuration, is proposed and investigated for low profile and multi-band performance in wireless communication systems. Fractal antenna is characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation compared to conventional microstrip antenna. The proposed self-affine rectangular fractal antenna shows multiband behavior due to self-affinity in their geometrical structure. Fractal is implemented on rectangular patch of dimension 40mm x 30mm embedded on ground plane of dimension 60mm x 60mm.The antenna is designed on a substrate of dielectric constant €r=4.4 and thickness 1.6mm. The base antenna is designed and simulated for 2.3 GHz. Further the base antenna is modified to first iteration fractal antenna and then to second iteration fractal antenna. Along with fractal design the EBG structures are also added to the proposed antennas. The antenna with first iteration and EBG is resonating at 1.9 GHz giving a bandwidth of 91 MHz. The antenna with second iteration and EBG shows multiple frequency resonances at 1.27GHz 1.6 GHz, 2.7 GHz, 3.44GHz, and 3.8GHz The antenna with second iteration indicates size reduction of 52.67% and gives over all bandwidth of 259 MHz. The proposed antenna is simulated using IE3D and simulated results are in good agreement with measured results.

Now-a-days in modern wireless telecommunication systems, antennas with smaller size, greater efficiency, and wider bandwidths are in great demand. To fulfil these requirements fractal concept in antennas is very popular which provides compactness and can generate multiple frequencies and also enhances its bandwidth. So this paper presents design and simulation of Square shaped fractal antenna using HFSS 15.0 software. This Square shaped fractal antenna is designed for 3 GHz resonant frequency using FR-4 epoxy as substrate. Also the simulated results are presented in this paper.

The presence of harmonics are undesirable in many applications. Embedding fractal technology into an antenna makes it possible to reduce the physical size, increase its operating bandwidth and directivity. However, the technique can cause significant undesired harmonics problems associated with higher order modes of the antenna. This paper presents simulation and measurement work of a reduced size Koch fractal meander dipole antenna that has tunable capability of a reconfigurable operation within the observed range of 400Mhz to 3.5GHz. Each undesired harmonic is removed using one or two stubs. A microwave switch-able dipole antenna concept using Koch curve integrated with open circuit stubs is presented. The structure employed fractal technology that can eliminate higher order modes. With the utilization of Koch curves, the antenna size is reduced, but the number of higher order modes has proportionally increased. The size of the proposed antenna is small with regards to the operating frequency. The stub has improved the antenna performance.

This paper presents the design of Multi-Band Passive RFID Tag Antenna with rectangular fractal shape and two operating bands for Radio Frequency Identification (RFID). The proposed antenna has wide and dual bandwidth verified by Simulated. It covers the wide frequency range including microwave bands of a 2.45GHz and 5.8GHz. This design of multiband antenna shows promising results at two different

Rapid development of wireless technology in recent years demands novel designs of wideband, low-profile antenna elements. Planar bow-tie dipole is a well-known antenna that can provide multiband and wideband radiation performance. This paper presents the detailed study of wideband radiation characteristics of planar solid and strip fractal bow-tie dipoles and discusses their prospective applications for multiband wireless communications antenna system.

Abstract— A fractal monopole antenna based on the Sierpinski gasket is studied in this paper. The monopole antenna based on the Sierpinski gasket constructed through three iterations displays a multiband behaviour with three bands that are log-periodically spaced by a ...

Numerical and experimental investigations are presented for a cascaded frequency selective surface (FSS) with Koch fractal conducting patch elements. The work is developed in two steps. In the first step two Koch fractal FSS screens are designed using the Ansoft Designer™ software. In the second step these FSS are cascaded and separated by an air gap layer to improve the bandwidth behavior. The structures are cascaded using Teflon spacers and screws to obtain the air gap. Thereafter, a numerical cascading technique is used to analyze the effect of the air gap between the cascading structures.

A fractal monopole antenna based on the Sierpinski gasket is studied in this paper. The monopole antenna based on the Sierpinski gasket constructed through three iterations displays a multiband behaviour with three bands that are log-periodically spaced by a factor of 2, the same scale factor that defines the geometrical self-similarity of the Sierpinski fractal. The simulated as well as measured input return loss and radiation patterns all display multi-band behaviour. The geometrical scale factor of the Sierpinski fractal is then changed to see whether the bands are shifted according to the new scale factor or not. The simulated results showed that the band positions could be controlled by changing the scale factor but on account of poor input matching. This poor input matching of Sierpinski fractal monopole antenna with modified scale factor is rectified using microstrip feed technique. The simulated as well as measured results of the antenna are in good agreement.

Abstract— A fractal monopole antenna based on the Sierpinski gasket is studied in this paper. The monopole antenna based on the Sierpinski gasket constructed through three iterations displays a multiband behaviour with three bands that are log-periodically spaced by a ...

A Novel coplanar waveguide (CPW) fed Ultra Wideband (UWB) antenna is presented. The proposed antenna is designed on RT/duriod 5880 substrate with thickness of 1.57 mm and relative permittivity of 2.2 having loss tangent 0.0009 using a second iteration Sierpinski carpet fractal with overall dimension of 37 mm × 46 mm × 1.57 mm. The designed antenna offers a good impedance bandwidth from 3.1 to 11 GHz. The presented antenna has omnidirectional radiation pattern and good gain flatness suitable for UWB applications.

Abstract A triple-frequency antenna combining a dual-band and a monoband antenna with broadside radiation patterns is presented. The dual-band antenna is inspired in the Sierpinski fractal. Such a dual-band antenna is stacked over a monoband antenna. The ...