Fractal Patch Research Articles

Design and analysis of reconfigurable fractal antenna with RF-switches on a flexible substrate for X-band applications

This paper presents a compact reconfigurable elliptical shaped fractal patch (ESFP) antenna with elliptical shaped RF MEMS switch is used for satellite applications at X-band. The proposed work involves the incorporation of RF MEMS switches loaded using parasitic elements with ease of simpler implementation without using DC bias lines. The proposed antenna is integrated with two MEMS switches and reconfigurability is obtained for varying the capacitance of the switch by actuating the switch to ON and OFF states. The elliptical shape is considered for the proposed microstrip patch antenna is to attain large flexibility in the design and attain good return loss, radiation patterns, gain and bandwidth of the antenna. The proposed antenna is designed on flexible polyamide substrate and resonating frequency is obtained at 9.07 GHz frequency with − 43 dB return loss with gain of 6.05 dB. When the proposed switch is integrated on to the elliptical patch fractal antenna it resonates at four different operating frequencies. Among all the four states the state-4 resonates at 9.02 GHz frequency with − 52.8 dB return loss with gain of 6.36 dB. The ESFP antenna has perform four operating frequencies with two RF-MEMS switches for reconfigurability applications. The simulated results are in good agreement between the measured results. A small deviation is observed between simulated and measured results.

MULTIBAND ELLIPTICAL PATCH FRACTAL AND DEFECTED GROUND STRUCTURES MICROSTRIP PATCH ANTENNA FOR WIRELESS APPLICATIONS

MULTIBAND ELLIPTICAL PATCH FRACTAL AND DEFECTED GROUND STRUCTURES MICROSTRIP PATCH ANTENNA FOR WIRELESS APPLICATIONS

MIMO Antenna Design and Optimization with Enhanced Bandwidth for Wireless Applications

This paper demonstrates a compact MIMO (Multi Input Multi Output) fractal type antenna for ultra-wide band applications. The proposed antenna is manufactured on a lowcost substrate material and the design is analyzed for various iterations in terms of reflection coefficient, gain, and bandwidth. The 50 Ω transmission line feed is used for both fractal patches and a metamaterial structure is used as the ground plane. The proposed design achieved a wide-band frequency response between 5.8 and 15 GHz, with the reflection coefficient of less than –10 dB. Reduced mutual coupling, positive gain and stable radiation patterns were observed throughout the operating band as well. The bandwidth of 9.2 GHz is achieved with the use of a metamaterial structure on the ground plane. The ECC and diversity gain obtained prove the excellent diversity performance of the antenna. The design was simulated using HFSS software and was tested in a lab.

Development of an Inverted-h Shaped Fractal Microstrip Patch Antenna for Cognitive Radio

In this paper, development of an inverted-h shaped multiband fractal microstrip antenna is presented for spectrum sensing in cognitive radio applications. An attempt is further made to optimize the proposed antenna using nature-inspired metaheuristic Moth flame optimization to achieve desired performance in 1.382 GHz, 2.623–3.101 GHz, 4.628–11.98 GHz and 13.22–20 GHz. This antenna is having multiple wide bands and almost omnidirectional radiation pattern, as per the requirements of spectrum sensing antennas for cognitive radio applications.

Design and Optimization of Micro-Machined Sierpinski Carpet Fractal Antenna Using Ant Lion Optimization

This study investigates the optimized Sierpinski carpet fractal patch antenna and also explores the possibility of the integration of the proposed design with monolithic microwave integrated circuits. The optimization process has been performed using an ant lion optimization algorithm to achieve the required operating frequency and impedance matching. Further, due to surface waves excitation in the high index substrates used for the antenna design, the performance of the antenna degrades. Therefore, a process of micro-machining has been adopted to overcome this limitation. The micro-machining process creates an air cavity underneath the patch which further creates the low index environment in the patch antenna causing drastic improvement in the performance parameters along with the compatibility with monolithic microwave integrated circuits. The design shows multiple resonance frequencies in X-band and Ku-band. The proposed micro-machined design shows the resonance at 7.9 GHz, 9.6 GHz, 13.6 GHz, and 19 GHz with a maximum gain of 6 dBi.

Synthesis and Mechanical Reconfiguration of Ground Plane Tilted Microstrip Antennas Based on Tetra-Circle Fractals

Abstract A synthesis procedure of a mechanically reconfigurable antenna based on tetra-circle fractal patch elements is presented, enabling to change both resonant frequencies and radiation pattern performance. The antenna geometry reconfiguration is implemented by tilting the ground plane of the microstrip antenna with respect to the fractal patch and substrate layer. The tilt angle is defined as the angle between the back of the dielectric substrate and the tilted ground plane and is electromechanically varied using a thin rod of dielectric material sliding up and down, in a simple geometry. Simulation results for the proposed antenna parameters are obtained using Ansoft HFSS software. In addition to promoting frequency and pattern reconfiguration, the tilting of the ground plane has proven to be an alternative to increase the antenna gain and enable single-band or dual-band operation. Prototypes were fabricated and measured for comparison purpose showing a good agreement between simulation and measurement results.

A Circular Shaped Fractal Patch Antenna for Multiband Applications

The principle purpose of this paper is to design a microstrip patch antenna using the circular fractal shape through HFSS software so that the designed antenna would be beneficial in multifarious bands with low cost, less physical size and most vitally high bandwidth. The results obtained are also very close and even accurate to match with the current world.

A complementary Sierpinski gasket fractal antenna array integrated with a complementary Archimedean defected ground structure for portable 4G/5G UWB MIMO communication devices

AbstractThis article presents the design, development, and experimental validation of an aperture coupled complementary Sierpinski gasket equilateral triangular fractal antenna array for portable 4G/5G UWB communication devices. The proposed antenna array is printed on two FR‐4 substrate layers (ε r = 4.4, height = 1.57 mm, and tan δ = 0.024) with two fractal triangular patches on the top layer (separated by a distance of 3λ/2) and feed network on the bottom layer of FR‐4. The fractal patches (optimized up to second order of iteration) are fed using an aperture‐coupled feeding mechanism, where the aperture slots in the ground layer are modified to complementary Archimedean spiral slots which are interconnected by a modified “X” shaped slot to improve the impedance matching at the operational bands. The proposed array has overall volumetric dimensions of 41 × 99.4 × 3.245 mm3 and provides a size reduction of 46% for the metallic area using the fractal geometry. The proposed array shows a simulated UWB response from 4.3 to 11.6 GHz (fractional bandwidth of 91.8% at 7.95 GHz) with a simulated peak gain of 4.7 dB (at 9.2 GHz) and port‐to‐port isolation of ≤−15.8 dB for the entire band. For validation of simulated responses, the proposed array is fabricated and tested for S‐parameters (S11, S22, S12, and S21). A measured impedance bandwidth of 6.3 GHz is observed for a frequency band from 5.7 to 12 GHz. Two additional frequency bands are also exhibited by the array from 4.1 to 4.25 GHz and 4.7 to 5.3 GHz. The array diversity parameters such as envelope correlation coefficient (≤0.007 [simulated], ≤0.0057 [measured]), diversity gain (≥9.999 [simulated], ≥9.971 [measured]), mean effective gain (≥−3.9 dB [simulated], ≥−5.1 dB [measured]), and channel capacity loss, (≤0.37 bits/s/Hz [simulated], ≤0.4 bits/s/Hz [measured]) which are calculated using the simulated and measured S‐parameters of the array are also observed. These parameters allow the proposed fractal array to be implemented in a diversity combining technique to improve the overall SNR and hence support a high data rate for 4G/5G multimedia services.

Square microstrip multi band fractal antenna using EBG structure for wireless applications

PurposeApplication of electromagnetic band gap (EBG) i.e. electromagnetic band gap technique and its use in the design of microstrip antenna and MIC i.e. microwave integrated circuits is becoming more attractive. This paper aims to propose a new type of EBG fractal square patch microstrip multi band fractal antenna structures that are designed and developed. Their performance parameters with and without EBG structures are investigated and minutely compared with respect to the resonance frequency, return loss, a gain of the antenna and voltage standing wave ratio.Design/methodology/approachThe fractal antenna geometries are designed from the fundamental square patch and then EBG structures are introduced. The antenna geometry is optimized using IE3D simulation tool and fabricated on low cost glass epoxy FR4, with 1.6 mm height and dielectric materials constant of 4.4. The prototype is examined by means of the vector network analyzer and antenna patterns are tested on the anechoic chamber.FindingsCombining the square fractal patch antenna with an application of EBG techniques, the gain of microstrip antenna has been risen up and attained good return loss as compared to the antennas without EBG structures. The designs exhibit multi-frequency band characteristics extending in between 1.70 and 7.40 GHz. Also, a decrease in antenna size of 34.84 and 59.02 per cent for the first and second iteration, respectively, is achieved for the antenna second and third without EBG. The experimental results agree with that of simulated values. The presented microstrip antenna finds uses in industrial, scientific and medical (ISM) band, Wi-Fi and C band. This antenna can also be used for satellite and radio detection and range devices for communication purposes.Originality/valueA new type of EBG fractal square patch microstrip antenna structures are designed, developed and compared with and without EBG. Because of the application of EBG techniques, the gain of microstrip antenna has been risen up and attained good return loss as compared to the antennas without EBG structures. The designs exhibit multi-frequency band characteristics extending in between 1.70 and 7.40 GHz, which are useful for Wi-Fi, ISM and C band wireless communication.

UWB Pentagonal Shaped Fractal Patch Antenna for Wireless Capsule Endoscopy

The capsule endoscopy device is one of the most important devices that have been invented recently because of its importance in facilitating the process of imaging the digestive system. The process of developing and improving the transmitter in the capsule is one of the most important things to improve images and accelerate the process of imaging. Microstrip antenna will be used because it has several benefits such as small size, ease of manufacture and low cost. In this paper, the microstrip antenna was designed with ultra-wideband technology (UWB) by using fractal geometry. The proposed antenna has a return loss of -25.1 at 5.45 GHz and VSWR of 1.13. Also, the radiation patterns are Omni-directional radiations over the UWB bandwidth.

SAW-TOOTH SHAPED SEQUENTIALLY ROTATED FRACTAL BOUNDARY SQUARE MICROSTRIP PATCH ANTENNA FOR WIRELESS APPLICATION

SAW-TOOTH SHAPED SEQUENTIALLY ROTATED FRACTAL BOUNDARY SQUARE MICROSTRIP PATCH ANTENNA FOR WIRELESS APPLICATION

PERFORMANCE COMPARISON OF DIFFERENT FRACTAL SHAPE ANTENNAS FOR ULTRA WIDE BAND APPLICATIONS

A related analysis of fractal antennas with distinct geometry is done in this paper. Patch shapes (square, hexagon, and circle), which are suitable for ultra-wideband applications have been considered. The fractal monopole square fractal is designed by novel Giuseppe Peano geometry, hexagon fractal patch antenna is formed by Koch structure and circle by Minkowski fractal elements. Matching for microstrip feed input is provided by rectangular ground plane. FR4 substrate has been used for fabrication purpose. The analogy is established on the output values of return loss, bandwidth, VSWR, group delay, gain, directivity and axial ratio. This investigation will help the design engineers to select the preferred aerial according to fractal geometry. The proposed antennas find its application in X-ray, W-LAN, WI-max, biomedical applications and so on.

A Design of Compact T- Shaped Fractral Patch Antenna for X- Band Applications

In this paper, a compact T-shaped fractal patch antenna has been designed and simulated using IE3D software for X-band applications with 9.0GHz as resonant frequency. Iterations of 3rd order have been performed to enhance efficiency, improvise antenna parameters like return loss, VSWR, directivity, fractional bandwidth, etc. The designed antenna is very compact having dimensions (16mm x 18mm x 1.6mm) and uses FR4 glass epoxy substrate with thickness of 1.6 mm, dielectric constant εr=4.4 and loss tangent δ = 0.025. Probe feeding method has been used. The designed antenna can be used for various X-band (i.e. 8GHz to 12GHz) applications like in radar applications, terrestrial communications and networking, space communications, etc

Dual-Band Dual-Linear Polarization Reflectarray for mmWaves/5G Applications

A dual-band dual-linear polarization reflectarray configuration is developed for future 5G cellular applications. A single layer unit cell including two pairs of miniaturized fractal patches is designed to operate at two distinct frequencies within the Ka-band (27/32 GHz), in a dual-polarization mode. An in-depth analysis of the unit cell behavior is carried out, to demonstrate the total independence between the designed frequency bands and polarizations. The proposed configuration offers a very simply and thin structure, small unit cell sizes, and low losses, while leading to an independent optimization of the phase at each frequency and polarization. A dual-band/dual-polarized reflectarray prototype is designed and tested, thus demonstrating the unit cell flexibility to offer arbitrary beam directions/shapes at each frequency, for both polarizations.

Triple Frequency CPW Fed Fractal Antenna for Wireless Applications

A Triple Frequency CPW feed fractal patch antenna has been designed for the S and C band applications with the operating frequencies of 2.29GHz, 3.46GHz and 5.89GHz. Patch has been etched with slots in a periodic manner which led for the generation of triple band of resonance. Flame Retardant Glass epoxy is taken as substrate material which is having a thickness of 1.6mm and a 50Ω stripline has been used to excite the antenna. Fractal technique has been implemented to attain the triple frequency of operation. The overall dimension of the antenna is 60mm×60mm×1.6mm. The Proposed antenna is having resonance which is covering the S and C band frequencies with a return loss value less than -10dB for entire bandwidth. Commercially available 3D simulator Ansys HFSS software has been used to design the proposed antenna.

Compact asymmetric fractal frequency and pattern reconfigurable monopole antenna

A compact frequency and pattern reconfigurable monopole for LTE and WLAN applications is presented. The antenna consists of an asymmetric fractal patch which is derived from a bow-tie antenna and optimized using Pattern search algorithm. The antenna operates at 1.8 GHz and 5.2 GHz frequency with a different radiation pattern for each case. A single PIN diode is used to achieve frequency and pattern reconfigurability. The antenna is simulated using Ansoft High Frequency Structural Simulator (HFSS) software and fabricated on FR4 substrate with the relative permittivity of 4.4; having size of 30 mm * 24 mm and thickness of 1.6 mm.

Defected Ground Based Fractal Antenna for S and C Band Applications

Defected ground based modified rectangular fractal patch antenna for mobile devices communication in Delay Tolerant Networks, Wireless sensor networks and Mobile Adhoc networks is being presented in this paper. In view of the overwhelming demand of small and light weight micro-chip patch antenna in wireless communication in the recent years the size of antenna has been reduced considerably. Wideband behaviour of antenna is achieved with improved values of performance parameters like gain, reflection coefficient (S11), Voltage Standing Wave Ratio (VSWR), radiation pattern and bandwidth. The proposed antenna covers various frequency bands like earth to space communication (2.17–2.2 GHz), satellite communication (2.3 GHz), wireless local area networks (2.4–2.484 GHz), Wi Fi (2.4 GHz for 802.11b and 802.11g), Radio Frequency Identification, Microwave oven, Bluetooth (2.45 GHz), Wireless Computer Networking (2.4 GHz), Mobile Wi-Max (2.5–2.69 GHz), Direct to home services (2.5–2.7 GHz), Wi-Max (3.3–3.6) Satellite Communication for Downlink (3.7–4.2 GHz) at various resonating frequencies. High Frequency Structural Simulator; v13 has been used to simulate the proposed antenna. The antenna has been designed and simulated using FR4 epoxy substrate with relative permittivity 4.4 and having size of 32 mm × 30 mm × 1.6 mm with line feeding technique. Ground plane has also made defective. The antenna shows the bandwidth of 2830 MHz with gain of 6.83 dB, reflection coefficient (S11) − 19.72 dB and VSWR of 1.23 at resonant frequency 2.85 GHz. Size of the antenna stands reduced by 38.73% with deflective ground surface and frequency shifted towards the lower side. The antenna operates from 2.05 to 4.88 GHz covering S and C band applications.

Frequency Reconfigurable Fractal Patch Circularly Polarized Antennas for GSM/Wi-Fi/Wi-MAX Applications

Frequency reconfigurable circularly polarized (CP) fractal antennas are presented. At first, a fractal shaped slot is inscribed on the bigger size fractal structure. Inside the scratched opening, a small size asymmetrical fractal patch is embedded and switching diodes are brought along x and y – sides to attach these internal and external patches. By applying asymmetrical fractal curves as boundaries, imbalance is developed inside the structure for CP. The sizes of the inner and outer patches are chosen in the sort of manner to resonate the antenna at GSM (1.8 GHz), WLAN (2.45 GHz) and Wi-MAX (3.4 GHz) bands, respectively. The fractal curve parameters are optimized to enhance CP radiation. Four switches are used to govern the antenna. Measured and simulation outcomes are in near agreement, which proves that the suggested antennas are well ideal for WLAN/Wi-MAX, GSM/Wi-Fi, GSM/Wi-Fi/Wi-MAX applications. Similarly, several frequency reconfigurable antennas have been studied by using various fractal curves.

Ultra-thin flexible fractal antenna for 2.45 GHz application with wideband harmonic rejection

This paper presents, the design, and characterization of a coplanar waveguide (CPW) fed ultra-thin, low-profile, and flexible fractal antenna with a wideband harmonic rejection for 2.45-GHz ISM band spectrum applications. The antenna consists of rectangular fractal patches and a stub, etched on a very thin substrate. The fractal patch is utilized to achieve miniaturization of 30% with respect to conventional quadrilateral patch antenna. A rectangular stub is introduced perpendicular to the feedline to minimize the harmonics over a wide frequency band 3.3–11.0 GHz. Simulated and measured results demonstrate that the antenna offers an operating band 2.276–2.72 GHz, which fully covers the ISM band (2.4–2.5 GHz). Along with this, the antenna exhibits promising radiation characteristics of omnidirectional gain around 2.2 dBi and radiation efficiency of better than 95%. The proposed antenna has a compact overall size of 0.24λo × 0.20λo × 0.0005λo (λo is the free-space wavelength at 2.45 GHz) along with other advantages, including ultra-thin geometry and wide harmonic rejection. These features make the proposed antenna become a potential candidate for ISM band applications.

A Sierpinski Carpet Five Band Antenna for Wireless Applications

A compact Sierpinski Carpet square fractal multiband antenna operating at 3.9 (WiMAX) /6.6 (Satellite TV) /8.1/10.7/11.8 GHz (X-band) is presented. The proposed Microstrip Patch Antenna (MSPA) consists of a Sierpinski Carpet square fractal radiator in which square slots are etched out and a tapered microstrip feed line. The Sierpinski Carpet square fractal patch modifies the current resonant path thereby making the antenna to operate at five useful bands. Impedance matching at these bands are solely achieved by using Sierpinski square slot and tapered feedline, thus eliminating the need of any external matching circuit. The dimensions of the compact antenna is and exhibits S 11 <-10dB bandwidth of about 4.8% (4.01-3.82 GHz), 2.1% (6.62-6.48 GHz), 2.7% (8.24-8.02 GHz), 2.1% (10.77-10.54 GHz) and 21% (12.1-11.60 GHz) with the gain of 7.57/3.91/3.77/6.74/1.33 dB at the operating frequencies 3.9/6.6/8.1/10.7 and 11.8 GHz, respectively under simulation analysis carried out by using HFSS v.13.0.