Fractal Monopole Research Articles

A CPW‐fed fractal monopole antenna with a reduced ground plane in frequency range of 500 MHz‐5.5 GHz

AbstractIn this article, the authors propose a super wide band CPW‐fed fractal monopole antenna suitable for phased array antennas with a shaped beam radiation pattern, operating in the frequency ranges below and above 1 GHz at the same time. The antenna has an octagonal radiator with fractals of the same shape added to its edges and sides. Also, the symmetrical elliptical ground planes have reduced the antenna size and, consequently, the mutual coupling in the antenna array. Despite the super‐wide frequency range, the antenna's radiation pattern is relatively steady in the E‐plane, and the negligible ripple on the radiation pattern makes it suitable for shaped beam radiation patterns in phased array design. The single‐element antenna with an overall size of 0.24λ × 0.38λ at 500 MHz is printed on an FR‐4 substrate. The outcomes of the simulation and measurement are well agreed in the frequency band of [500 MHz to 5.5 GHz] with an impedance bandwidth (|S11|< −10dB) of 166.67% and VSWR< 2. Also, the fidelity factor of the antenna is studied to investigate the SWB performance.

Fractal Sectoral Monopole Antenna for UWB Band Applications

This paper proposes a fractal monopole antenna based on a sectoral-shaped patch. To improve thegain of the proposed antenna over a larger bandwidth, the matching was enhanced by attaching two rectangular stubs to the feeding line. The antenna, which is built on an FR4 epoxy substrate with εr =4.3 and a loss tangent of 0.018 has a compact size of 28 mm×31 mm×1.6 mm. The antenna covers the UWB range and extends to about the 22 GHz frequency, as well as offers omnidirectional radiation patterns. The optimized configuration was fabricated and tested. The impedance bandwidth of the proposed antenna is about 155% with a reflection coefficient better than −10 dB and has a maximum gain of nearly 4 dBi with a relatively stable omnidirectional radiation pattern.

A Fractal Monopole Antenna With Dual Polarization Reconfigurable Characteristics for X-Band Applications

A Fractal Monopole Antenna With Dual Polarization Reconfigurable Characteristics for X-Band Applications

A Compact High Isolation Four Elements MIMO Antenna System for 5G Mobile Devices

A Compact high isolation Multi Input Multi Output Antenna system working on 3.5 GHz (3400 - 3600) MHz is presented for the 5G mobile terminals. Four-antenna elements are employed to construct the proposed MIMO antenna system. These antennas are located over two slim side-edges frame of a mobile device to meet the present trend requirements of slim and full-screen smartphone devices. A modified Hilbert fractal monopole antenna and an I-shaped feeding line construct the antenna element’s front part, while an L-shaped shorted to the system’s ground plane are used to the antenna element’s back part. The overall monopole antenna element’s size printed on the mobile frame’s side edge is (9.72 mm × 5.99 mm) so the desirable antenna miniaturization is achieved. Based on the spatial diversity and self-isolated techniques, high isolation (better than 16.3 dB) is attained by the proposed four-element MIMO antenna system. To assess the proposed antenna element’s performance, the scattering parameters, antenna gains, antenna efficiencies, and radiation pattern characteristics have been evaluated. Besides, the MEGs and ECCs are investigated to appreciate the proposed system’s MIMO performance. Desired antenna and MIMO performances are achieved by the proposed four-element MIMO antenna system so it can be a good candidate for the future 5G mobile handsets.

Sierpinski carpet fractal monopole antenna for ultra-wideband applications

Microstrip antenna is broadly used in the modern communication system due to its significant features such as light weight, inexpensive, low profile, and ease of integration with radio frequency devices. The fractal shape is applied in antenna geometry to obtain the ultra-wideband antennas. In this paper, the sierpinski carpet fractal monopole antenna (SCFMA) is developed for base case, first iteration and second iteration to obtain the wideband based on its space filling and self-similar characteristics. The dimension of the monopole patch size is optimized to minimize the overall dimension of the fractal antenna. Moreover, the optimized planar structure is proposed using the microstrip line feed. The monopole antenna is mounted on the FR4 substrate with the thickness of 1.6 mm with loss tangent of 0.02 and relative permittivity of 4.4. The performance of this SCFMA is analyzed in terms of area, bandwidth, return loss, voltage standing wave ratio, radiation pattern and gain. The proposed fractal antenna achieves three different bandwidth ranges such as 2.6-4.0 GHz, 2.5-4.3 GHz and 2.4-4.4 GHz for base case, first and second iteration respectively. The proposed SCFMA is compared with existing fractal antennas to prove the efficiency of the SCFMA design. The area of the SCFMA is 25×20 mm<sup>2</sup>, which is less when compared to the existing fractal antennas.

Proposed Multiband Fractal Monopole Antenna for WLAN and WiMax Applications

Proposed Multiband Fractal Monopole Antenna for WLAN and WiMax Applications

A Compact Self-Isolated MIMO Antenna System for 5G Mobile Terminals

A compact self-isolated Multi Input Multi Output (MIMO) antenna array is presented for 5G mobile phone devices. The proposed antenna system is operating at the 3.5 GHz band (3400–3600 MHz) and consists of eight antenna elements placed along two side edges of a mobile device, which meets the current trend requirements of full-screen smartphone devices. Each antenna element is divided into two parts, a front part and back part. The front part consists of an I-shaped feeding line and a modified Hilbert fractal monopole antenna, whereas the back part is an L-shaped element shorted to the system ground by a 0.5 mm short stub. A desirable compactness can be obtained by utilizing the Hilbert space-filling property where the antenna element’s overall planar size printed on the side-edge frame is just (9.57 mm × 5.99 mm). The proposed MIMO antenna system has been simulated, analyzed, fabricated and tested. Based on the self-isolated property, good isolation (better than 15 dB) is attained without employing additional decoupling elements and/or isolation techniques, which increases system complexity and reduces the antenna efficiency. The scattering parameters, antenna efficiencies, antenna gains, and antenna radiation characteristics are investigated to assess the proposed antenna performance. For evaluating the proposed antenna array system performance, the Envelope Correlation Coefficients (ECCs), Mean Effective Gains (MEGs) and channel capacity are calculated. Desirable antenna and MIMO performances are evaluated to confirm the suitability of the proposed MIMO antenna system for 5G mobile terminals.

A Novel Energy Harvesting Antenna Design for Battery-less IoT devices

Energy harvesting is a process in which small amounts of energy are captured from radiative radio frequencies (RF) that would otherwise be lost as heat, light, sound, or movement. The captured energy allows improving the efficiency of wireless communications, where it enables new technologies such as battery-less devices or power internet of things (IoT) devices without the need for batteries. This paper presents a novel antenna design, called an icosahedron-Sierpiński fractal monopole antenna, where the advantage of such a geometry is in its ability to capture a wide range of frequencies due to its multi-band characteristic and three-dimensional characteristics. The performance of the antenna has been evaluated by numerical simulations and compared with the already existing research. The proposed antenna geometry has been designed using AUTOCAD2020 and simulated on COMOSOL 5.4 to operate at frequencies between 0.84GHz, 1GHz, 1.6 GHz, 2.4GHz, and 3GHz.

Compact wideband hybrid fractal antenna loaded on AMC reflector with enhanced gain for hybrid wireless cellular networks

A wideband hybrid fractal monopole antenna loaded with artifical magnetic conductor (AMC) is proposed. Using a hybrid fractal generator, the monopole antenna achieves self-similarity compactness, reduced size and good wideband performances. The ground is semi-elliptic and has defected steps aiming to improve impedance matching and X-pol. reduction. The AMC reflector has 3× 3 array of cesaro shaped unit cells looped in a square metallic conductor. The AMC enhances radiation gain with back-lobe reduction. The AMC unit cell produce a 00 phase reflection at fAMC = 4.5 GHz and then loaded to optimize antenna performance. To validate the design, a prototype antenna is fabricated and measured. The antenna operates from (3.7–7.0) GHz with 61.68% impedance bandwidth, realized gain of (8.7–13.8) dBi, and radiation efficiency > 82.5%. The proposed antenna leverages on compactness, low-profile AMC height and good boresight radiation gain, which shows its potential for hybrid wireless cellular networks.

Flexible polymer/fabric fractal monopole antenna for wideband applications

Flexible polymer/fabric fractal monopole antenna for wideband applications

A Wideband Rectenna Using High Gain Fractal Planar Monopole Antenna Array for RF Energy Scavenging

This paper introduces a wideband rectenna that can scavenge ambient wireless power to a range of frequency band from 0.91 GHz to 2.55 GHz efficiently. The proposed rectenna is based on a wideband 2 × 2 fractal monopole antenna array with omnidirectional radiation patterns and high gains of 5 to 8.3 dBi at the desired bands. An improved two-branch impedance matching technique is presented which is designed to enhance the rectifier circuit performance with a relatively low input power ranging from −25 dBm to 10 dBm. Also, a full-wave wideband rectifier that can suitably improve the RF-to-DC power conversion efficiency is designed for the rectenna. A peak efficiency of 76%, 71%, 61%, and 62% is obtained at 950, 1850, 2100, and 2450 MHz, respectively. Measurement results show that a conversion efficiency of 68% has been achieved over an optimal 4.7 kΩ resistor when the simultaneous four-band input power level is −10 dBm. Moreover, an output DC voltage of around 243 mV with voltage varying within 160–250 mV can be achieved by gathering the low ambient wireless power inside laboratory. This study proves that the proposed rectenna can be applied to a range of many low-power electronic applications.

Design and Analysis of Fractal Based Monopole Antenna Backed with Modified Jerusalem Cross Frequency Selective Surface for Wireless Personal Area Communications

This paper presents a low profile Single-layer Modified Jerusalem Cross Frequency Selective Surface (SMJC FSS) which functions as a band-stop filter to shield the 2.45 GHz Industrial, Scientific and Medical (ISM) band with a unit cell size of 0.249λg × 0.249λg × 0.027λg. Compared to JC FSS, 50% size reduction is achieved by the effect of capacitive and inductive loading. The proposed FSS exhibits a fractional bandwidth of 14.69% and fractional bandwidth dimension ratio (FBDR) of 8775.4, which is one of the highest among the single layer FSS. The Koch curve inspired fractal monopole antenna is backed by 5 × 5 FSS array, which contributes enhanced gain and fractional bandwidth of 6.28 dB and 23.75% respectively and has a net dimension of 75 × 75mm ×31.2 mm. The specific absorption rate (SAR) is analyzed on human arm model where proposed antenna attains 0.183 W/Kg, which makes it appropriate for the application of body area communication. The measured results agree well with the simulated results and hence it is validated for wireless personal area communications in the ISM band at 2.45 GHz.

A Multiband antenna using plus‐shaped fractal‐like elements and stepped ground plane

A multiband planar symmetrical plus-shaped fractal monopole antenna with stepped ground plane is presented in this study. Measured results show that the proposed antenna operates with 10 dB return loss bandwidths from 1.630 to 1.88 GHz and from 4.5 to 8.5 GHz covering The Global System for Mobile Communications (GSM) 1800 MHz 2G spectrum band, 4400 to 4900 MHz 5G spectrum band adopted by Japan and China for future 5G communication in sub-6 GHz band, 5.15 to 5.925 GHz LTE band 46, WLAN IEEE 802.11 y/a/h/j/n/P bands, and 5.8 to 7.707 GHz military band. The antenna gain varies between 1.73 and 1.97 dB in lower band and 3.6 to 5.05 dBi in upper band with radiation efficiencies more than 90% in lower band and more than 80% in upper band. The antenna has more than 64 and 28 dB isolations between the copolar and cross-polar radiation patterns in the lower and upper bands, respectively.

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.

Miniaturised low‐profile super‐wideband Koch snowflake fractal monopole slot antenna with improved BW and stabilised radiation pattern

This communication explores the super-wideband Koch snowflake fractal monopole slot antenna for different wireless/multiband applications. The antenna comprises of a modified star-shaped patch, a 50 Ω triangular tapered feedline, a partial slot loaded ground plane and an I-shaped parasitic element located beneath the radiating element. The self-similarity and space-filling features of Koch iteration technique have been employed at the triangular patch to acquire the antenna compactness and broadband performances. Further by placing a pair of symmetrical L-shaped slots and an inverted U-shaped slot in the ground plane, a super-wide-impedance bandwidth (BW) ( ) of 650 MHz–20 GHz with a ratio BW of 30.7:7 is attained. The proposed antenna has a compact size of 17 × 29 × 0.787 mm 3 and has a stable radiation pattern over the entire frequency spectrum. For pattern stability, an I-shaped parasitic element was utilised. Moreover, the typical antenna parameters such as return loss, gain, radiation pattern and group delay have been simulated and verified experimentally. Time-domain characteristics have also been studied.

An UWB trapezoidal rings fractal monopole antenna with dual‐notch characteristics

An ultra-wideband planar fractal monopole antenna with dual-notch characteristics is presented in this article. The microstrip fed antenna consists of nested trapezoidal rings and defected ground plane. Measured results show that the proposed antenna operates with a 10 dB return loss bandwidth from 2.2 to 10.8 GHz with notch bands at (2500-2690) MHz and (3300-4200) MHz covering LTE 2500, WiMAX and part of C-band.

Corrugated fractal monopole antenna with enhanced bandwidth for ultrawideband applications

A very compact coplanar waveguide (CPW)-fed fractal monopole antenna with a modified ground plane is presented. The main objective is to obtain ultra wideband (UWB) characteristics from a simple microstrip monopole antenna. A wideband behaviour and good impedance matching are obtained by modifying the ground plane to semi-trapezoidal shape. Further, the self-similar fractal nature is introduced in the radiating element to enhance the bandwidth. The proposed antenna shows a wider impedance bandwidth from 3 GHz to 11.2 GHz for S11 &–10 dB. A fractional bandwidth of about 115.5% (impedance bandwidth ratio 3.73:1) is achieved for the third fractal iteration. The total volume of the presented antenna is 18×12×1.6 mm³. The measurements are carried out to validate the simulations and the performance of the proposed antenna is analysed.

Corrugated fractal monopole antenna with enhanced bandwidth for ultrawideband applications

Corrugated fractal monopole antenna with enhanced bandwidth for ultrawideband applications

Design of Compact Dual-band Fractal Monopole Antenna with Virtually Extended Ground Plane

Achieving a particular response to serve multiple wireless applications is regarded as the primary demand in our modern age because of the considerable development of the communication devices. In this paper, a compact monopole antenna with reduced ground plane has been suggested to meet the requirements of the dual-band WLAN applications. The antenna miniaturization has been carried out in employing two techniques. Initially, the fractal geometry has been applied to the antenna radiating element. Two-sided Koch fractal curves up to the third iteration have been used to increase the path of electrical current on the surface of the radiating element which is in the form of a square with dimensions. To gain more miniaturization, the antenna ground plane has been further reduced by using different lengths of two open-ended parallel stubs to form a virtually extended ground plane. This supportive technique has been adopted as a tuning means to control the path of the electrical currents exciting the resulting resonances. The proposed antenna and has been printed on an FR-4 substrate with a thickness of 1.6 mm and 4.4 relative dielectric constant and is fed by 50-ohm microstrip feed line. The resulting antenna dimensions are of about 19.1 mm × 19.1 mm. A parametric study has been carried out, and the results reveal that the proposed antenna offers a dual-band performance with a considerable ratio of resonant frequencies covering the existing 2.4/5.2/5.8 GHz WLAN applications, besides many other communication services.

Microstrip Line Fed Fractal Monopole Antenna with Defected Ground Structure

This paper presents a wideband polarized antenna that is designed and analyzed for the cellular communication applications. The proposed antenna is designed with the coplanar wave guide feeding (CPW) by using the RT/ duroid 5880 material with a dielectric constant 2.2. It is observed that in the proposed model the return loss is -21.40dB for ungrounded CPW where as for the grounded CPW the loss is reduced to -39.13dB. The gain for the ungrounded CPW fed antenna is 2.95 dB and is enhanced to 3.2dB with grounded CPW structure. It is observed that there is an improvement in the bandwidth upto 6.03 GhZ for grounded CPW when DGS is applied. The antenna designing and simulation is done using ANSOFT HFSS software.