A Comprehensive Classification and Analysis of Geomagnetic Storms Over Solar Cycle 24

A geomagnetic storm is a global disturbance of Earth?s magnetosphere,occurring as a result of the interaction with magnetic plasma ejected from the Sun.Despite considerable research,a comprehensive classification of storms for a complete solar cycle has not yet been fully developed,as most previous studies have been limited to specific storm types.This study,therefore,attempted to present complete statistics for solar cycle 24,detailing the occurrence of geomagnetic storm events and classifying them by type of intensity(moderate,intense,and severe),type of complete interval(normal or complex),duration of the recovery phase(rapid or long),and the number of steps in the storm?s development.The analysis was applied to data from ground-based magnetometers,which measured the Dst index as provided by the World Data Center for Geomagnetism,Kyoto,Japan.This study identified 211 storm events,comprising moderate(177 events),intense(33 events),and severe(1 event)types.About 36%of ICMEs and 23%of CIRs are found to be geoeffective,which caused geomagnetic storms.Up to four-step development of geomagnetic storms was exhibited during the main phase for this solar cycle.Analysis showed the geomagnetic storms developed one or more steps in the main phase,which were probably related to the driver that triggered the geomagnetic storms.A case study was additionally conducted to observe the variations of the ionospheric disturbance dynamo(Ddyn)phenomenon that resulted from the geomagnetic storm event of 2015July 13.The attenuation of the Ddyn in the equatorial region was analyzed using the H component of geomagnetic field data from stations in the Asian sector(Malaysia and India).The variations in the Ddyn signatures were observed at both stations,with the TIR station(India)showing higher intensity than the LKW station(Malaysia).

Royal Crown Shaped Polarization Insensitive Perfect Metamaterial Absorber for C-, X-, and Ku-Band Applications

This study proposed a new royal crown-shaped polarisation insensitive double negative triple band microwave range electromagnetic metamaterial absorber(MA).The primary purpose of this study is to utilise the exotic characteristics of this perfect metamaterial absorber(PMA)for microwave wireless communications.The fundamental unit cell of the proposed MA consists of two pentagonal-shaped resonators and two inverse C-shaped metallic components surrounded by a split ring resonator(SRR).The bottom thin copper deposit and upper metallic resonator surface are disjoined by an FR-4 dielectric substrate with 1.6 mm thickness.The CST MW studio,a high-frequency electromagnetic simulator has been deployed for numerical simula-tion of the unit cell in the frequency range of 4 to 14 GHz.In the TE mode,the offered MA structure demonstrated three different absorption peaks at 6.85 GHz(C-band),8.87 GHz(X-band),and 12.03 GHz(Ku-band),with 96.82%,99.24%,and 99.43%absorptivity,respectively.The electric field,magnetic field,and surface current distribution were analysed using Maxwell’s-Curl equations,whereas the angle sensitivity was investigated to comprehend the absorption mechanism of the proposed absorber.The numerical results were verified using the Ansys HFSS(high-frequency structure simulator)and ADS(advanced design system)for equivalent circuit models.Moreover,the proposed MA is polarisation and incident angle independent.Hence,the application of this MA can be extended to a great extent,including airborne radar applications,defence,and stealth-coating technology.

Low Profile UHF Antenna Design for Low Earth-Observation CubeSats

This paper reveals a new design of UHF CubeSat antenna based on a modified Planar Inverted F Antenna(PIFA)for CubeSat communication.The design utilizes a CubeSat face as the ground plane.There is a gap of 5 mm beneath the radiating element that facilitates the design providing with space for solar panels.The prototype is fabricated using Aluminum metal sheet and measured.The antenna achieved resonance at 419 MHz.Response of the antenna has been investigated after placing a solar panel.Lossy properties of solar panels made the resonance shift about 20 MHz.This design addresses the frequency shifting issue after placing the antenna with the CubeSat body.This phenomenon has been analyzed considering a typical 1U and 2U CubeSat body with the antenna.The antenna achieved a positive realized gain of 0.7 dB and approximately 78%of efficiency at the resonant frequency with providing 85%of open space for solar irradiance onto the solar panel.

Inkjet Printed Metamaterial Loaded Antenna for WLAN/WiMAX Applications

In this paper,the design and performance analysis of an Inkjetprinted metamaterial loaded monopole antenna is presented for wireless local area network(WLAN)and worldwide interoperability for microwave access(WiMAX)applications.The proposed metamaterial structure consists of two layers,one is rectangular tuning fork-shaped antenna,and another layer is an inkjet-printed metamaterial superstate.The metamaterial layer is designed using four split-ring resonators(SRR)with an H-shaped inner structure to achieve negative-index metamaterial properties.The metamaterial structure is fabricated on low-cost photo paper substrate material using a conductive inkbased inkjet printing technique,which achieved dual negative refractive index bands of 2.25–4.25 GHz and 4.3–4.6 GHz.The antenna is designed using a rectangular tuning fork structure to operate at WLAN and WiMAX bands.The antenna is printed on 30×39×1.27 mm3 Rogers RO3010 substrate,which shows wide impedance bandwidth of 0.75 GHz(2.2 to 2.95 GHz)with 2 dB realized gain at 2.4 GHz.After integrating metamaterial structure,the impedance bandwidth becomes 1.25 GHz(2.33 to 3.58 GHz)with 2.6 dB realized gain at 2.4 GHz.The antenna bandwidth and gain have been increased using developed quad SRR based metasurface by 500 MHz and 0.6 dBi respectively.Moreover,the proposed quad SRR loaded antenna can be used for 2.4 GHz WLAN bands and 2.5 GHz WiMAX applications.The contribution of this work is to develop a cost-effective inject printed metamaterial to enhance the impedance bandwidth and realized the gain of a WLAN/WiMAX antenna.