Fractal Defected Ground Structure Research Articles

Circularly polarized fractal defected ground monopole antenna for Bluetooth/LTE/CNSS/S-band and CA- band applications

ABSTRACT In this article, an antenna structure consisting fractal defected ground monopole antenna for circularly polarized radiation is presented. The characteristics of circular polarization in the proposed structure are obtained by fractal defected ground structure. The third iterative h-shaped fractal slot antenna is fabricated and examined on Rogers RT/duroid 5880 substrate for validating the simulated results. The best circular polarization radiation is obtained by varying the key parameters of the proposed geometry. The simulated and measured results confirmed that the proposed antenna can be adequately produced an impedance bandwidth (2.15 GHz – 3.55 GHz) of 49.12% with 3 dB axial ratio bandwidth (2.54 GHz – 3.03 GHz) of 17.59%, while the measured peak gain of the proposed structure is 2.99 dBic. The proposed work is suitable for Bluetooth/LTE/CNSS/S-band and CA-band applications.

Circularly polarized parasitic patch slot antenna using I-tree fractal defected ground structure for CA band applications

Abstract In this article, a single feed antenna design which consists of a parasitic patch slot with an I-tree shaped fractal defected ground structure for circularly polarized radiation is presented. In the proposed design, circular polarization characteristics are achieved by deploying fractal slotted defected ground structures. The antenna design with a third iterative I-tree shaped fractal slot on an Fr4 substrate is fabricated and tested for verifying the simulated results. The circular polarization mechanism is performed using parametric studies. The measured and simulated results confirmed that the proposed structure can adequately generate an impedance bandwidth of 10.6% with 3 dB axial ratio bandwidth of 4.89%, with the measured peak gain of the proposed antenna being 5.16 dBic. The proposed article is suitable for C-band and CA-band applications.

Monostatic Radar-Based Microwave Imaging of Breast Tumor Using an Ultra-wideband Dielectric Resonator Antenna (DRA) with a Sierpinski Fractal Defected Ground Structure

Monostatic Radar-Based Microwave Imaging of Breast Tumor Using an Ultra-wideband Dielectric Resonator Antenna (DRA) with a Sierpinski Fractal Defected Ground Structure

Design and Performance Study of Single and Multi-Layered Fractal Based Miniaturized Patch Antennas for 2.4 GHz Applications

The design and characterization of single and multi-layered miniaturized microstrip antennas resonating at 2.4 GHz are proposed. The miniaturization is accomplished by fractal Defected Ground Structure (DGS). The DGS used for miniaturization is a Modified Minkowski Fractal DGS (M-MFDGS). The proposed size reduction process with M-MFDGS follows the selection of the best antenna configuration and its design parameters through sensitivity analysis and pattern search optimization. Microstrip patch antennas with three different feeding mechanisms are considered here to validate the effect of DGS over the size reduction and performance improvement. Incorporating M-MFDGS in three antennas, the first one with microstrip line feed accomplishes a maximum patch area reduction of 70% among the three proposed structures with a gain of 1.43 dBi. Likewise, with a slightly higher dimension than the first structure, the second antenna with proximity-coupled feed achieves a higher gain (5.11 dBi) and bandwidth (110 MHz). Although the size reduction in the third antenna with aperture-coupled feed is a little less it has the highest gain (5.91 dBi) among all the three. All three compact antennas are physically fabricated and the simulated results are validated with the measured results.

Triple Band Notch Microstrip Patch Antenna with Fractal Defected Ground Structure

ABSTRACT Microstrip patch antenna compatible in size with fractal defected ground structure (FDGS) has been designed and fabricated to enable successful implementation in modern communication systems. This attempt is dedicated to the wireless application of emergency management. In this paper, the presented structures are based on the coplanar waveguide (CPW) fed patch radiating element in conjunction with fractal geometry as a tuning stub. CPW feed is utilized to obtain the ultra-wideband (UWB) capacity of the presented antenna. Fractal structure as patch stub is employed to decrease the size of the antenna. The employed structure is tuned with the proficient Particle Swarm Optimization (PSO) technique for required frequency of emergency management. In light of investigating the band notching properties, slot of meander curve geometry and FDGSs is critically analyzed and discussed. Experimental tests on the manufactured prototype are conducted to examine the effectiveness of the antenna.

Analysis and Design of Microstrip Filters Using Photonic Band Gap Ground Plane with Fractal Periodic Pattern (Dept.E)

In the present work, four different techniques are used in designing the microstrip low pass filters (LPF). These techniques include LPF with fractal defected ground structure (DGS), LPF with continuous minkowiski fractal element, multi-stop band filter with discontinuous minkowiski element, and finally a wide multi-stop filter with separated interdigcap shape. A microstrip PBG filter of minkowiski element and interdigcap shape was designed to operate as a multifrequency band stop filter. With an appropriate fractal geometry of minkowiski and interdigcap elements, a wide stop-band at different frequencies are obtained. A continuous sinusoidal fractal slots are designed to work as a wide LPF. A novel fractal DGS for the microstrip LPF is proposed. The proposed fractal DGS can provide better band gap, and slow-wave characteristics. The numerical results show that a LPF of continuous and discontinuous fractal minkowiski elements in ground plane is obtained with a bandwidth 0 - 3 GHz for a slot width 0.5mm. However, if the slot width is taken equal 0.2 mm, the bandwidth is increased up to 10 GHZ. With suitable choice of number of elements, one can control the filter bandwidth. With a discontinuous fractal minkowiski and interdigcap element in ground plane, the filter response is forced to have a stop band at resonance frequency of fo and repeated at 2fo, .. etc. The numerical results obtained using an analytical technique with the aid of a numerical package (Sonnet) which is used in microstrip analysis.

Design of circularly polarized antenna using inclined fractal defected ground structure for S-band applications

ABSTRACT A single feed square patch with inclined fractal defected ground structure (IFDGS) microstrip antenna for circular polarization (CP) is proposed in this article. The CP radiation is achieved by an inclined fractal-shaped slot is embedded along the diagonal axis of a ground plane. To enhance the performance parameters of this antenna like axial ratio bandwidth, return loss bandwidth, and gain, an inclined fractal structure is slotted into the ground plane. The parameter studies of the IFDGS are given to illustrate the way to obtain CP radiation. The CP antenna with the third iterative IFDGS is fabricated and measured. The measured results validate simulated results and show good agreement. The proposed antenna achieved CP radiation at 2.61 GHz with an overall size of 41 × 41 × 1.6 mm3. It shows an impedance bandwidth of 5.53% at center frequency of 2.6 GHz and 3-dB axial ratio (AR) bandwidth of 1.14% at center frequency of 2.61 GHz. The measured peak gain for the proposed antenna is found as 4.12 dBi. The proposed antenna can be suitable for wireless communication in S-band.

Analysis and design of inclined fractal defected ground-based circularly polarized antenna for CA-band applications

AbstractDesign of single-feed circularly polarized (CP) microstrip antenna is proposed in this article. The design employs the concept of E-shape patch with inclined fractal defected ground structure (IFDGS), which can improve the impedance bandwidth, gain, and axial ratio (AR) bandwidth. The excellent enhanced impedance bandwidth, axial ratio bandwidth, and gain are achieved by an inclined E-shaped fractal etched on the ground plane. The parameter studies of the E-shaped IFDGS are given to illustrate the way to obtain CP radiation. The third iterative IFDGS is fabricated on easily available FR4 substrate with a size of 0.494 λ0 × 0.494 λ0 × 0.019 λ0 (λ0 is the wavelength in free space at 3.624 GHz). The measured results verify the simulated results and show good agreement. The proposed antenna shows an impedance bandwidth of 12.7% at a centre frequency of 3.47 GHz and 3-dB AR bandwidth for this band is 2.39% at a centre frequency of 3.626 GHz. The measured peak gain for the proposed antenna is found as 8.1 dBi. The proposed antenna can be suitable for mobile WIMAX operation (IEEE 802.16e-2005 standard), wireless communication in CA-band and FCC.

Highly compact microstrip patch design based on improved capacitive Minkowski fractal defected ground structure

This article proposes an effective approach for designing a highly compact patch antenna for wireless applications at 2.4 GHz. Size reduction is realized here by adding a modified Minkowski fractal defected ground structure (M-MFDGS) under the center of the radiating patch. The antenna miniaturization procedure follows a sensitivity study for the selection of appropriate DGS shape. Incorporating this highly capacitive M-MFDGS, the resonant frequency of the patch is reduced from 4.16 GHz to 2.4 GHz without any alteration in the physical size of the microstrip patch. This enables a 71% reduction in the radiating patch compared to the conventional antenna at the same operating frequency. The variation in the antenna resonance characteristics is also validated by an equivalent transmission-line model. The fabricated antenna prototype with a very low patch size of 0.15 λ0 × 0.13 λ0, has a 10-dB return loss bandwidth of 5.20%, a realized gain of 1.4 dBi, and radiation efficiency of 65% centered at 2.41 GHz. With this novel approach, the proposed miniaturized patch antenna is found to be a suitable candidate for portable wireless communications.

The Circular Polarization Diversity Antennas Achieved by a Fractal Defected Ground Structure

This paper proposes the circularly polarized (CP) antennas with a restored radiation pattern for the polarization diversity applications. The proposed CP antennas have dual polarizations, the left-handed circularly polarized (LHCP) antenna is designed for transmitting and the right-handed circularly polarized (RHCP) antenna is designed for receiving. The CP antenna operation and the radiation pattern restoration are realized by a fractal defected ground structure (FDGS). When achieving the radiation pattern restoration, the proposed CP antennas forward efficiencies are improved from 66.8% to 81% and the forward realized gains are improved from 2.56 dBi to 5.38 dBic, respectively.

Compact CPW-fed UWB MIMO antenna with a novel modified Minkowski fractal defected ground structure (DGS) for high isolation and triple band-notch characteristic

A compact printed ultra-wideband (UWB) multiple input multiple output (MIMO) antenna with coplanar waveguide feed for portable UWB applications is presented. The radiator and ground plane of the antenna are etched with an overall size of 26.75 mm × 41.5 mm. The UWB MIMO antenna consists of two planar identical monopole antenna elements and a novel modified Minkowski fractal defect is introduced in the ground plane for enhancing the isolation of the MIMO system. The proposed antenna has an impedance bandwidth (for │S11│ < −10 dB) ranging from 3.1 to 11.5 GHz (VSWR ≤ 2) and an isolation of more than 15 dB is achieved between the adjacent planar monopoles. The band rejection phenomenon in wireless local area network band is achieved by etching rotated C-shaped slots from the respective patches. Also, two identical rectangular slots are etched on the respective ground planes which enhances the lower UWB bandwidth and cause interference suppression at Wi-Max and C-band (3.3–3.7 and 3.7–4.2 GHz), respectively. A further improvement in isolation from 14.71 to 21.81 dB is achieved by the addition of parallel rectangular strips at the back side of the antenna. Acceptable agreement is obtained between the simulated and measured antenna performance parameters.

A New Technique to Design Circularly Polarized Microstrip Antenna by Fractal Defected Ground Structure

A new technique to design single-feed circularly polarized (CP) microstrip antenna is proposed. The CP radiation is obtained by adjusting the dimension of the etched fractal defected ground structure (FDGS) in the ground plane. Parameter studies of the FDGS are given to illustrate the way to achieve CP radiation. The CP microstrip antennas with the second and third iterative FDGS are fabricated and measured. The measured 10-dB return-loss bandwidth of the CP microstrip antenna is about 30 MHz (1.558 to 1.588 GHz), while its 3-dB axial-ratio bandwidth is 6 MHz (1.572 to 1.578 GHz). The gain across the CP band is between 1.7 and 2.2 dBic.

Design of Compact Bandpass Filters based on Fractal Defected Ground Structure (DGS) Resonators

Modified Minkowski fractal geometry has been found to be attractive for microwave circuit designers because of its high space-filling property. This property will lead to the design of compact circuits; meeting the requirements of the modern communications systems to be with small size. In this paper, the design of a compact microstrip BandPass Filters (BPF) has been proposed based on the modified Minkowski fractal (DGS) resonators. The proposed BPF structure is composed of two coupled resonators etched as fractal DGS structures. Results reveal that as the iteration level of fractal based DGS becomes higher, more compact filter structure will result in. Furthermore, the presented DGS structures with fractalshaped resonators can be adopted to design compact planar BPFs with reasonable performances. The performance curves offered by the resulting filters are characterized by the low loss across the passband and high rejection levels outside it with steep roll-off in both edges of passband. Measured results of a fabricated prototype of a 2nd iteration fractal DGS BPF have shown reasonable agreement with those predicted by simulation. Measured results of a 2nd iteration fractal DGS BPF have shown satisfactory agreement as compared with simulation results. There is a slight shift of the lower edge of the passband response of the transmission characteristics, while the upper edge is s very close. The results have shown that the filter has reasonable performance characteristics with considerable reduction of higher harmonics. The compact size of the proposed filter together with the realized high selectivity will make it suitable for a broad range of the recently available wireless communication services.

Mutual Coupling Reduction by Novel Fractal Defected Ground Structure Bandgap Filter

This paper presents a novel fractal defected ground structure (FDGS) to reduce mutual coupling between coplanar spaced microstrip antenna elements. The structure of the proposed FDGS is studied. Bandgap characteristic of second and third iterative FDGS is achieved. The second and third iterative FDGSs are used to reduce mutual coupling between microstrip antenna elements. Mutual coupling reduction performance of third iterative FDGS is better than that of second iterative FDGS. And dimension of FDGS can be decreased by using higher level iterative FDGS. The third iterative FDGS is fabricated and measured. Simulated and measured results both show that more than 35-dB mutual coupling reduction is obtained by using the third iterative FDGS. Moreover, the envelope correlation of antenna elements with FDGS is quite smaller than that of antenna elements without FDGS.

Compact substrate integrated waveguide filter using dual-plane resonant cells

A dual-plane resonant cell wideband bandpass filter is proposed and designed on substrate integrated waveguide (SIW) cavities using U-shape slots and H-shape fractal defected ground structure (DGS). The U-shape slots etched on the top meta layer of the SIW cavity are used to constitute a multiple-mode resonator and the H-shape fractal DGS etched on the bottom metal layer can greatly improve the filter performance while keeping the overall size of the filter circuit to be much compact. The proposed filter can lead to a size reduction of approximately one-third compared with the traditional SIW filters only using U-shape slots on the top metal plate of the SIW cavity. The filter has been fabricated and experimentally measured. The measured data are in good agreement with the simulated results. The measured 3 dB bandwidth is from 7.15 to 11.25 GHz, representing a fractional bandwidth of 44.6% at a center frequency of 9.2 GHz. Within the passband, the measured return loss performance is quite good (below −22dB), and the insertion loss is measured to be 1.05 dB, including the loss from two SMA connectors. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:111–114, 2016

Design and testing of a compact circularly polarised microstrip antenna with fractal defected ground structure for L‐band applications

A compact circularly polarised (CP) microstrip antenna for mobile satellite communication band of India (1.492-1.518 GHz) is presented. Two asymmetric length rectangular shape slots, perpendicular to each other are printed on the circular patch for realisation of CP radiation. To improve the performance parameters of patch antenna such as axial ratio (AR) bandwidth, return loss bandwidth, radiation efficiency and so on a new technique of combination of fractal theory and defected ground structure (DGS) is proposed for the first time in design of CP antennas. 44.74% size reduction in patch size, enhancements of 62.73% in AR bandwidth, 70.74% in return loss bandwidth and 4.03% in radiation efficiency is achieved as compared with conventional patch antenna, after incorporation of Koch curve fractal DGS in the ground plane. The performance of the developed antenna has been compared with other available L-band planar antennas in the literature, and it is found that the developed structure is better one in many aspects. Laboratory prototype of the antenna is fabricated and experimentally measured for cross verifying the simulated results.

Compact dual-band truncated patch antenna with fractal defected ground structure for wireless applications

In this paper, a compact, dual-band patch antenna is proposed over Minkowski fractal defected ground structure (DGS) for bandwidth enhancement of global positioning system (GPS) applications. The proposed design combines the truncated dual L-shaped slits cut on diagonal corners of radiating patch and fractal defect on the metallic ground plane. This concept shifts the frequencies to lower bands with improvement in antenna radiation properties. By deploying symmetrical and asymmetrical boundaries to the structure for the fractal DGS on metallic ground plane, improvement in bandwidth and gain are obtained. Compact antenna size is achieved for dual-band GPS frequencies of L1 (1.575 GHz) and L2 (1.227 GHz). The measured results for antenna prototype are (1.2–1.245 GHz): L2 band and (1.51–1.59 GHz): L1 band for 10 dB return loss bandwidth with better pattern radiation. Gain value with and without DGS is observed for compact antenna overall volume of 0.32λ0 × 0.32λ0 × 0.024λ0.

A novel antenna design with fractal-shaped DGS using PSO for emergency management

This article presents an analysis and design of a novel planar antenna in corporation with fractal-shaped defected ground structure (DGS) for wireless communication devoted to emergency management. The conventional ground plane can be replaced by a fractal DGS ground plane to get size reduction, better efficiency and suppress surface-waves. The synthesis of the proposed antenna is carried out by means of particle swarm optimisation (PSO) to identify the geometrical descriptors of the structure. The representative results reveal that the proposed geometry exhibits better impedance matching and multiband characteristics in comparison to conventional planar antenna (without any defects). The analyses from simulations and numerical validations are reported in order to illustrate the effectiveness of varying scale factor that contributes 69.08% size reduction of ground plane.

A novel antenna design with DGS for emergency management

This paper presents an analysis and design of a novel planar antenna in corporation with fractal shaped defected ground structure (DGS) for wireless communication devoted to emergency management. The conventional ground plane can be replaced by a Fractal DGS ground plane to get size reduction, better efficiency and suppress surface-waves. The synthesis of proposed antenna is carried out by means of particle swarm optimization (PSO) to identify the geometrical descriptors of the structure. The representative results reveals that the proposed geometry exhibit better impedance matching and multiband characteristics in comparison to conventional planar antenna (without any defects). The analyses from simulations, numerical and experimental validations are reported in order to illustrate the effectiveness of varying scale factor that contributes 69.08% size reduction of ground plane.

Lowpass filter with reduced fractal defected ground structure

Presented is the design of a planar lowpass filter with stubs separated by transmission lines. To minimise dimensions, the filter is completed by a fractal defected-ground structure (DGS). The fractal DGS filter requires a 20% smaller substrate compared to a conventional filter with stubs.