Advanced Electromagnetics (E-Journal)
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Metamaterial Based Circular Disc Patch Antenna Miniaturization
No full textA novel metamaterial structure has been proposed for its operation at 2.4 GHz. A circular disc patch antenna resonating at dual band frequency with 2.4 GHz and 3.36 GHz has been designed using full field solver CST MWS tool and the loading effect of the metamaterial has been shown. The loading of metamaterial shows a radial size reduction of 56.71% in the circular disc patch (dimensional space reduction by 81.26%) while the effect of loading the metamaterial array and loading the metamaterial with defected ground plane show that without reducing the disc patch radius, the patch antenna can resonate at 1.00 and 1.942 GHz respectively, these yield a lower frequency shift of 58.33% and 19.79%. The designed metamaterial consists of two copper conductive concentric circular rings over a polyimide substrate. Various antenna parameters such as S11, VSWR, Bandwidth, Gain, Directivity and Radiation efficiency have been obtained for the circular disc patch antenna, circular disc patch antenna loaded with the metamaterial, circular disc patch antenna loaded with an array of metamaterial and are compared. A spice circuit has been derived for the reflection coefficient of the circular disc patch without loading the metamaterial, circular disc patch loaded with metamaterial using Keysight based ADS tool for its inclusion in a traditional electrical circuit solver tool
A Novel Circular Slotted Microstrip-Fed Patch Antenna with three Triangle Shape Defected Ground Structure for Multiband Applications
No full textIn this paper, a novel circular slotted rectangular patch antenna with three triangle shape Defected Ground Structure (DGS) has been proposed. Radiating patch is made by cutting circular slots of radius 3 mm from the three sides and center of the conventional rectangular patch structure and three triangle shape defects are presented on the ground layer. The size of the proposed antenna is 38 X 25 mm2. Optimization is performed and simulation results have been obtained using Empire XCcel 5.51 software. Thus, a miniaturized antenna is designed which has three impedance bandwidths of 0.957 GHz, 0.779 GHz, 0.665 GHz with resonant frequencies at 3.33 GHz, 6.97 GHz and 8.59 GHz and the corresponding return loss at the three resonant frequencies are -40 dB, -43 dB and -38.71 dB respectively. A prototype is also fabricated and tested. Fine agreement between the measured and simulated results has been obtained. It has been observed that introducing three triangle shape defects on the ground plane results in increased bandwidth, less return loss, good radiation pattern and better impedance matching over the required operating bands which can be used for wireless applications and future 5G applications
Reconfigurable Multi-Beam Dual-Band Antenna based on Vee Dipoles
No full textThis paper presents a novel antenna configuration to support reconfigurable multi-beam feature with dual-band capability. The proposed design uses four double Vee dipoles with their arms printed on either sides of a substrate and fed through a single coaxial input probe. A single directional beam that can be configured in four directions at quadrature angle in the azimuth (xy-plane) and corresponding dual, triple and quad beams have been obtained by controlling the state of four PIN diodes. A prototype of the proposed antenna has been designed and fabricated. Measured antenna parameters are in good agreement with that of simulated parameters. This highly planar antenna shows similar radiation patterns at both design frequencies enabling concurrent dual-band communication for all fifteen possible beam configurations
Design of Circularly Polarized Modified Minkowski Fractal Based Antenna for UHF RFID Reader Applications
No full textA compact, square shaped microstrip fractal antenna with asymmetrical pairs of T-slits for circularly polarized (CP) radiation and radio frequency identification (RFID) reader applications is proposed and experimentally investigated. Design is based on narrow slit modified Minkowski island fractal geometry. Circular polarization along with size reduction is achieved by inserting four symmetrical pairs of T-slits at the square patch boundary of the single-probe-feed radiator. Proposed geometry is tuned at resonant frequency of 914 MHz by optimization of dimensions of the two T-slits. Compactness of the antenna is achieved by increasing the overall sizes of the slits. Antenna is fabricated on FR4 substrate with a size of 47.2×47.2×1.6 mm3 (0.143λ0 X 0.143λ0 X 0.005λ0) and tested to validate the simulated results. The 3-dB axial-ratio (AR) bandwidth and impedance bandwidth of the proposed antenna design are found to be 7 MHz (911-918 MHz) and 24 MHz (909-933 MHz) respectively. A design equation is develped based on the parametric study that can be used to design a compact antenna with CP for UHF RFID applications covering the frequency range from 887 to 1023 MHz
Survey on Electrical Activity in Earth’s Atmosphere
No full textLightning discharge is a spectacular, luminous and one of the most dangerous short lived phenomenon which occurs in the Earth’s atmosphere ranging from troposphere to the lower ionosphere. Lightning in troposphere is mainly classified as cloud-to-ground (CG) lightning, intra-cloud lightning and inter-cloud lightning discharges. It is assumed that these discharges are caused by the electrically charged thunderclouds. CG lightning has been studied more and is further categorized as positive CG and negative CG lightning. Positive CG lightning is more powerful and accounts only (5-10) percent of the total global lightning and may carry a peak current of >300 kA. An entire family of other electrical discharges also has been reported by the scientific community. They are called “Transient’s Luminous Events (TLE’s)”. TLEs occur from top of the thunderclouds up to the lower ionospheric altitudes. Their first visual evidence was documented in 1989. TLE’s are included as blue starters, blue jets, gigantic jets, red sprites, halos, and elves. They are named according to their optical properties, terminal altitudes and different shapes. It has been observed that TLE’s are associated with underlying thunderstorm activity and strong CG lightning.
The exact physical mechanism of lightning and TLE’s and their association with the underlying thunderstorms is still unknown and the research is going on. In this paper, we will study the possible mechanisms of these electrical discharges, their inter-connection and impacts on the atmosphere. This papers is aimed at the readers generally are unfamiliar with the lightning characteristics. We hope that this article will increase the interest among the researchers
An Insight into Impact of Partial Ground and Dual Trapezoidal Slots on Bandwidth and Gain considerations for a Microstrip Antenna Array for WiMax Application
No full textIn this work, design and analysis of microstrip patch antenna is carried out. A (2 X 1) antenna array is considered, with dimensions (W x L) as 35.11 mm x 27.13 mm. The dielectric substrate is taken to be FR4 epoxy with dielectric constant as 4.3 and loss tangent of 0.02. Dual trapezoidal slots are introduced to improve the gain considerations for the considered antenna array. The simulations are carried out and it is observed that the gain is improved. As a second stage in the work, to improve the bandwidth of operation for the dual trapezoidal antenna array, the concept of partial ground is taken into consideration. The simulations are carried in HFSS. It is found out that the introduction of partial ground improved the bandwidth of the antenna structure considered while preserving the gain to the maximum extent possible. The gain was found to be 7.0875 dB with centre frequency 2.4020 GHz. The frequency range below -10dB for the considered antenna array structure with partial ground was around 2.3 GHz to 2.6 GHz. This range is utilized in the WiMax application which covers the frequency ranges (2.3 GHz to 2.4 GHz) and (2.496 GHz to 2.690 GHz)
A High Gain Microstrip Patch Array for 5 GHz WLAN Applications
No full textThis paper presents the design, fabrication and measurement of a high gain 4-elements linear patch array, which uses the corporate feed technique with inset for excitation resonating at 5.21
A New Approach to the Analysis of Electromagnetic FEM Simulations Results at Electric Field Singularities
No full textA new methodology to the analysis of the results of Finite-Element Modeling (FEM) simulations at electric field singularities is proposed. The method, that can be easily applied in the post-processing phase of the electromagnetic FEM analysis workflow, is based on the weighted averaging of the calculated electric field magnitude within small volumes including the singularity point under investigation. In the paper, the proposed approach is applied to the electrical stress analysis of a high-voltage device modeled by means of a commercial electromagnetic FEM tool. In comparison to the conventional metric of the maximum field evaluation usually adopted for the analysis of electrical stress in insulators, our approach features several advantages: (i) the outcome of the analysis is independent of the numerical grid refinement at the singularity, thus allowing direct comparison of calculated electric field with the material dielectric strength; (ii) the method is robust against slight modifications of the geometrical shape of the singularity; (iii) on the other hand, for a given shape, the analysis outcome responds to significant variations of the singularity size or, in other words, of its sharpness; (iv) in the analysis of highvoltage devices, the approach can be applied for the estimation of the discharge volumes corresponding to different singularity types of different device geometries. In the paper, the new methodology is explained in details and is applied to simple but significant case studies
Spectral and Dispersion Properties of Long Period Fiber Grating for Optical Communication Systems
No full textPresent work deals with the analytical study of spectral and dispersion properties of long period fiber grating (LPFG) under linear regime. The standard parameters in the understanding of the optical features of an LPFG have been analyzed using the linear coupling processes such that one can appreciate without going through the cumbersome mathematical treatment of coupled mode equations the basic characteristics of the grating. We have analyze transmittance, phase factor, group delay and group velocity dispersion (GVD) of the LPFG as functions of physical parameters like operating wavelength, grating length, induced index change, and detuning parameter. Special attention is paid to the study of GVD with second and third order dispersion contribution as well as the filter characteristics and delay response of the grating. In case of strong grating, we find that at a particular grating strength the resonance band splits into two bands. Negative group delay for certain values of coupling strength suggested that an LPFG can also be used as dispersion compensator in optical fiber communication
Triple band Compact Fractal Antenna with Defected Ground Plane for Bluetooth, WiMAX, and WLAN Applications
No full textThis paper presents a novel compact coplanar waveguide (CPW) monopole fractal-shaped antenna using fractal patch composed of hexagons with defected ground plane. Inclusion of a pair of S-shaped slots on the ground plane is used to extend the antenna impedance bandwidth and to provide multiband operation. The antenna has a compact size of 35×35×1.27 mm3 which is compact. The antenna is designed, fabricated and measured. Good performances in terms of return loss, gain and radiation pattern are obtained in the operating bands, which makes the proposed antenna a good candidate for multiband wireless systems. The obtained results show that the antenna operates at Bluetooth,Worldwide Interoperability for Microwave Access (WiMAX), and Wireless Local Area Network (WLAN)