Fractal Antenna Research Articles

Coaxial Probe Fed Modified Sierpinski Fractal Antenna for Wireless Applications

A modified Sierpinski fractal antenna has been designed for wireless applications. The designed antenna exhibits multiple resonance behavior due to the basic attributes of the fractal shapes. The proposed antenna has planar, compact in size and is suitable for various wireless applications. It is designed on the Flame Retardant epoxy board substrate (FR4), which is very easily available, light in weight and has less cost. IFS (Iterated Function System) methodology is accustomed to generate the complex fractal layout using the scripting methodology (.vbs) in the HFSS simulator. Scripting method provides a straight forward solution to generate complicated fractal structures by generating code in MATLAB. The proposed antenna resonates at five different frequencies 1.859 GHz, 3.623 GHz, 5.929 GHz, 9.095 GHz and 9.547 GHz with smart values of return loss up to - 26 dB. It additionally demonstrates good radiation properties and has VSWR values less than two for all resonating frequencies. Radiation characteristics are displayed by 2D and 3D radiation patterns. It also has an low profile value of Gain of 3 dB.

Design of a linear array of fractal antennas with high directivity and low cross‐polarization for dedicated short range communication application

In this article, the authors proposed an eight-element linear array of fractal antennas for dedicated short range communication (DSRC; 5.9 GHz) service band. The single element of the array is a newly proposed fractal antenna whose radiating patch is derived from the Fibonacci series with the incorporation of Koch snowflake, and it poses a 2D quadrantal symmetry. The gain of the structure is improved by down shifting the radiating patch with respect to its ground plane. The feed network of the array is designed in such a manner to make the structure compact as well as to use the advantage of array mutual coupling for improving the array radiation pattern. The fabricated single element gives 7.54 dB gain and 128 MHz bandwidth with a radiation efficiency of η = 85.11%. The prototype array gives 15.18 dB gain with 105 MHz bandwidth and radiation efficiency of η = 72.12%. The measured cross-polarization of single element and the array along the direction of the main beam are less than −80 dB and −60 dB, respectively, in both the xz- and yz-plane. Both single element and the array are capable of satisfying the bandwidth requirements for DSRC applications.

Performance enhancement of nested hexagonal ring‐shaped compact multiband integrated wideband fractal antennas for wireless applications

In this paper, nested hexagonal ring-shaped fractal antennas are designed and investigated which are different from each other in patch orientation. Initially, the multiband integrated wideband hexagonal nested ring antenna is designed (antenna-I). To improve the multiband/wideband behavior, the patch orientation of antenna-I is changed to −60°/60° (antenna-II), −120°/120° (antenna-III), and −180°/180° (antenna-IV). Antennas are designed on low cost FR-4 glass epoxy substrate with relative permittivity of 4.4 and overall dimension 30 × 30 × 1.6 mm3. Comparison among antennas have been made and found that the antennas with negative orientation exhibit better results in terms of bandwidth, impedance matching, number of frequency bands, and gain. Designed antennas have been compared with each other and found that antennas-II and III are better in performance as compared to antennas-I and IV. Antenna-II exhibits wider bandwidth of 1.26 (2.52-3.78 GHz), 2.75 (4.03-6.78 GHz), and 6.1 GHz (7.82-13.92 GHz) with maximum gain of 7.14 dB. Similarly; antenna-III exhibits the bandwidth of 340 MHz (1.92-2.26 GHz), 820 MHz (3.04-3.86 GHz), 4230 MHz (5.38-9.61 GHz), and 3040 MHz (10.41-13.45 GHz) with a maximum gain of 6.19 dB. Prototype of the designed antennas with satisfactory orientations are fabricated and tested for the validation of results. Simulated and measured results are also juxtaposed and observed in good agreement with each other. Antennas exhibit bidirectional and omnidirectional pattern in E-plane and H-plane, respectively, also the radiation efficiency of antennas are in acceptable range from 75% to 95%. Due to the wider bandwidth of designed antennas, they can be used for different wireless standards such as Advance Wireless Services AWS-1, AWS-2, AWS-3, Wi-MAX, WLAN, X-band satellite communication, point-to-point wireless applications, ITU band, military satellite communication, television broadcasting, and military land and airborne systems.

Formation of Fractal Antenna Array for Multiband Applications

Antennas play a vital role in wireless communication; a thirst of excellence in this area is unending. Proposed work describes a concept of fractal multiband antenna designed in the hexagon shape. Basically fractal is the concept used in Microstrip antenna for giving better results than conventional Microstrip antenna. By using hexagonal fractal antenna we can possibly achieve the radiation pattern with high gain. The coaxial feeding is used and multiple hexagons are interconnected in array for maintaining conductivity and to preserve electrical self similarity. Hexagonal antenna is used for different wireless applications. The proposed antenna frequency band covers a large number of wireless communication applications including GPS (1.6GHz), Bluetooth (2.4 GHz) & WLAN (3.6GHz). Antenna design has been designed and simulated by using the software Ansoft’s HFSS and parameters like bandwidth return loss, directivity, VSWR are analyzed. Fabrication of the antenna is done by using wet-etching method, on FR-4 dielectric substrate material. Experimental results are taken on Vector Network Analyzer (VNA) and those obtained results were compared with simulated results. The hexagonal fractal antenna array is found to possess predictable multiband characteristics.

Design and Analysis of Sierpinski Carpet Fractal Antenna for UHF Spaced Antenna Wind Profiler Radar

This paper emphasizes the design of Sierpinski carpet fractal antenna to miniaturize the antenna array of UHF Spaced antenna Wind profiler radar that operates at 445 MHz. The proposed antenna is designed using High Frequency Structure Simulator (HFSS) where aluminium is used as a patch and ground with air as dielectric substrate due to it’s zero loss tangent .patch is separated from ground with help of hinges and fed with 50 ohm coaxial probe. The Sierpinski fractal antenna is designed till third iteration so as to reduce its size and weight by 33 percent.

Design and Simulation of Horizontally placed H-shaped Fractal Antenna

The design and simulation of horizontally placed H-Shaped Fractal Antenna is presented in this paper using CST Microwave Studio simulation software and the excitation is provided by using Nickel material for feeding in Y direction, wave guide port feeding method is used.. The simulated result shows that by edge cutting the directivity increases, return loss is very less and the voltage standing wave ratio is nearly equal to unity as the number of iterations increases. In generating multiple frequencies., the horizontally placed H shape fractal structure is advantageous. This antenna can be used in the Wi-Fi due to its better performance in Return loss, VSWR and directivity. In this paper four stages of this antenna is designed and simulated, the third iteration of this antenna is fabricated for Return loss and VSWR. The observations are conducted on antenna parameters such as the return loss for the frequency of 9.5 GHz is -27.6 dB and observed nearly equal value for measured results. The VSWR of both simulated and measured results are also same.

Fractal Antenna Design for Various Multiband Applications

In this paper “Micro Strip Patch Antenna (F-MSPA)” based on fractal is proposed to perform operations over multiband for a specific time bound. This is designed specifically for “Wireless Power Transmission (WPT)” System which is light weight or it is low profile and light weight when implemented. The main aim of proposed methodology or design of antenna is attained by implementing the basic patch called as the rectangular patch, whose scope is till the third level. Based on this the shape of rectangular cuttings are obtained. The antenna is excited by the obtained or generated micro strip feed as the operations of antenna are performed over various frequency ranges between 1GHz to maximum of 5 GHz. The proposed method comprises of fractal antenna resonant with quad frequencies that ranges: 1.86GHz / 2.29GHz / 3.02GHz / 4.50GHz along with their generated loss values are 13.59dB / -23.66dB / -15.94dB / -15.69dB. Proposed antenna simulation is performed using Ansoft HFSSv13 a high frequency structure simulator.

Novel coated differentially fed dual‐band fractal antenna for implantable medical devices

A novel differentially fed fractal antenna coated with a layer of a dielectric film and operating at two bands of Medical Implant Communication Services 402–405 MHz and Industrial, Scientific, and Medical 2.4–2.48 GHz, is investigated to enable sufficient data transmission rates, while featuring a ‘mode-control’ signal to prolong the battery life. The symmetrical fractal technology of Hilbert curve is employed to miniaturise the dimension. To facilitate interfacing with peripheral integrated circuits, differentially feeding is adopted. To demonstrate how common-mode noises are suppressed, for the first time, a detailed analysis about the noise suppression of the differential configuration with two feedings is presented. A layer of thin film is coated around the proposed antenna to isolate the effect of human tissues and alleviate the electromagnetic coupling with human body. Moreover, to draw a design methodological guideline, the key geometrical parameters are analysed numerically and theoretically. Health safety considerations, radiation performance, and link budgets are also discussed to validate the proposed antenna's applicability in biomedical telemetry.

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.

Compact and miniaturized metamaterial-based microstrip fractal antenna with reconfigurable qualification

Design procedure of a small dual-band antenna based on composite right/left-handed (CRLH) transmission line is proposed in this article. The conventional microstrip patch is assumed as a primary antenna and then, Minkowski-like fractal geometry is applied. The antenna has a compact size of 20 × 20 mm2, and operates efficiently at 4.4 GHz and 6.1 GHz. The antenna provides high gain of 3.8 dB and 6.2 dB in the two operating bands, respectively. It also has an omnidirectional radiation pattern with low cross-polarization level. The effect of the fractal structure along with CRLH transmission line concepton the miniaturization and multiband performance of the antenna have been studied. The related results show the accuracy of the theoretical studies and good agreement between simulated and measured results, which verify that the antenna is a suitable candidate for wireless communication applications.

Elliptical monopole based super wideband fractal antenna

AbstractAn elliptical monopole based third iterative fractal antenna for super wideband applications is investigated in this article. It consists of microstrip line fed three iterations of elliptical monopole in tree shaped manner and modified semielliptical ground plane. It has an impedance bandwidth of 0.65 to 35.61 GHz, that is, ratio bandwidth of 54.78:1. The overall footprint of the antenna is 170 × 150 mm2. A peak realized gain of 6.51 dB with an average gain of 3.24 dB is achieved. The investigated antenna has advantages of miniaturized dimensions, simple geometry, and wider bandwidth over previously reported structures.

Design and development of virtual instrument for fault diagnosis in fractal antenna array

This paper deals with the development of a virtual instrument for fault diagnosis in fractal antenna array using Lab-VIEW software. Faults in antenna array are considered on the basis of the radiation pattern. In this study, theta and gain values of radiation patterns for each fault are used in Lab-VIEW for curve fitting. An artificial neural network (ANN) has been developed for fitted data points using the Leavenberg Marquard algorithm in MATLAB software and mean square error (MSE) is minimized. The designed ANN model has been embedded in the virtual instrument. The proposed virtual instrument system gets test patterns as input and generates output for several faults present in antenna array. Simulated and measured results of the fractal antenna array are validated experimentally. This virtual instrument model has not been developed for fractal antenna array so far.

Double split labyrinth resonator-based CPW-fed hybrid fractal antennas for PCS/UMTS/WLAN/Wi-MAX applications

ABSTRACTIn this manuscript, the design of double split labyrinth resonator (DSLR)-based Coplanar waveguide (CPW)-fed hybrid fractal antennas has been presented for distinct wireless applications. The proposed hybrid antennas are designed by fusing the Hilbert and Koch fractal geometries together and the resulted structure is named Hilbert Koch–Koch Hybrid Fractal Antenna (HKKHFA). The proposed antennas differ from each other in the feed line locations only. The CPW feed line is applied to excite the antennas at two different locations as Left and Right CPW-fed, and the proposed antennas are also named HKKHFA with Left CPW-fed and HKKHFA with Right CPW-fed. The ground plane of the proposed antennas is being modified to attain the better results. The proposed HKKHFA with Left and Right CPW-fed are also being loaded with DSLR on the reverse side of substrate for attaining wideband characteristics, better impedance matching and enhanced gain. The overall size of the proposed HKKHFAs is 30 × 30 × 1.6 mm3 and is being designed on low-cost FR4 glass epoxy substrate with a relative permittivity of 4.4 and a thickness of 1.6. The results of unloaded and loaded proposed antennas (HKKHFA with Left and Right CPW-fed) are juxtaposed with each other and revealed that the loaded HKKHFA exhibits wider bandwidth and better impedance matching. Prototypes of HKKHFAs loaded with DSLR for both the feed locations are fabricated and tested for their results, and found good agreement between simulated and experimental results. The proposed HKKHFA loaded with DSLR for both CPW-feds exhibits the peak gain of 4.40/4.95 dB and a maximum bandwidth of 7.69/7.36 GHz, and it is useful for different wireless standards.

Novel sunflower MIMO fractal antenna with low mutual coupling and dual wide operating bands

AbstractA novel multiple-input and multiple-output (MIMO) fractal antenna excited by a coplanar waveguide was investigated in this study. A novel technique was used to improve the isolation of 20 dB between the dual radiating elements by inserting a strip line into the outer edges of the ground plane. A sunflower structure was used to configure the antenna in three steps. At each step, an additional sunflower structure was added with half the size of that used in the previous step to enhance the impedance bandwidth. The measured values of envelop correlation coefficient and total active reflection coefficient indicated that the proposed MIMO antenna has high-diversity performance between radiating elements. Wide dual operating bands of 2–2.9 and 5–10 GHz were obtained, which can support different wireless communications, such as 3G, LTE (2.6 GHz), WLAN (2.4 GHz/5 GHz), WiMAX (2.4 GHz/5GHz), ISM (2.4 GHz/5 GHz), 5G (5–6 GHz), and satellite communications (6–8 GHz). The MIMO fractal antenna with a small size achieved a maximum efficiency of 85% and a peak value gain of 6 dBi, low-channel capacity loss of 0.15–0.4 b/s/Hz, and high isolation between radiating elements is suitable for portable communication devices.

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.

A quad‐band Sierpenski based fractal antenna fed by co‐planar waveguide

AbstractIn this article, A Sierpenski based octagonal carpet fractal antenna is introduced for quad‐band applications. The proposed antenna developed with FR‐4 substrate material with relative permittivity of 4.4, thickness chosen is 1.6 mm and co‐planar waveguide feed is used in this design. The antenna is designed, simulated with computer simulation technology studio suite, printed and tested. The measurement results of proposed antenna resonates at 2.4, 4.45, 9.1, 10.24, 12.46 GHz and are well suited for C‐band(2.4 GHz), L‐band (4.45 GHz), X‐band (9.1 GHz, 10.24 GHz), Ku‐band (12.46 GHz) applications. Good agreement between the results of simulation and measurement is observed with applications.

Hexagonal fractal antenna for super wideband terahertz applications

A hexagonal fractal superwideband antenna operating at terahertz frequencies is presented in this paper. It consists of three iterations of a hexagonal slot loaded hexagonal radiator fed by a microstrip line, defected irregular partial ground plane along with a backed plane rectangular ring resonator. This antenna has an operating bandwidth of 0.2 THz–11.5 THz for VSWR≤2. Other frequency domain characteristics like distorted omnidirectional radiation patterns in both E & H planes and peak realized gain of 10.82 dB are observed. HFSS simulator is used for analyzing this antenna geometry.

Wireless sensor node remote supply using a compact stacked rectenna array with voltage multipliers at 2.45 GHz

AbstractThis paper presents compact rectenna arrays for ambient RF energy harvesting on the 2.45 GHz ISM band. The arrays are based on four and nine series-connected rectenna cells. Each cell is composed of a stacked fractal antenna and an RF-to-dc conversion circuit. The antenna is a compact third Koch fractal shape, fed by a coaxial probe for more compactness. The conversion circuit is a full-wave rectifier with a differential output, each DC polarity is provided by a two-stage Dickson voltage multiplier. Measurement results show a significant increase of the output DC voltage for the one, four, and nine cells rectenna arrays. They provide, for power density of 1.7 μW/cm2, an output DC voltage of 0.9, 2.2, and 4.1 Volts, respectively. The 9 cells rectenna array is used in a remote supply experiment of a temperature and acceleration wireless sensor, where the data are transmitted via a Bluetooth low energy link to a distant smartphone every 1 min.

Fractal Yagi-Uda antenna for WLAN applications

This paper describes the development of a Fractal printed Yagi-Uda antenna for Wireless Local Area Network (WLAN) applications operating at 2.4 GHz frequency. In miniaturizing the dimensions of an antenna, fractal method is applied where the 1st iteration and 2nd iteration is implemented. The Computer Simulation Technology (CST) software is used as the platform to design and simulate the antenna. The substrate material used is the FR-4 board which has a dielectric constant of 5.4, the thickness of 1.6mm and tangent loss of 0.019. The antenna performance interm of the reflection coefficient, radiation pattern and gain are compared and analyzed. For the 1st iteration, 22.81% of reduction size has been achieved and 30.81% reduction of the antenna size for 2nd iteration has been achieved.

Design of ultra-wide band fractal microstrip antenna

Design of ultra-wide band fractal microstrip antenna