Publisher: Advanced Electromagnetics   (Total: 1 journals)   [Sort alphabetically]

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Advanced Electromagnetics     Open Access   (Followers: 17, SJR: 0.154, CiteScore: 1)
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Advanced Electromagnetics
Journal Prestige (SJR): 0.154
Citation Impact (citeScore): 1
Number of Followers: 17  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2119-0275
Published by Advanced Electromagnetics Homepage  [1 journal]
  • Simple Giant Magnetoresistance Probe Based Eddy Current System of Defect
           Characterization for Non-Destructive Testing

    • Authors: D. R. Touil; A. Daas, B. Helifa, A. C. Lahrech, L. Ibn Khaldoun
      Abstract: The purpose of this paper is to present a new giant magnetoresistance (GMR) sensor, in eddy current testing technique for surface defect detection, in conducting materials, we show that the GMR based eddy currents probe is more sensitive than the inductive probe. A flat coil mounted on ferrite pot used to produce an alternate magnetic field, which gives rise to eddy currents in the material under test. Aluminum plates use with defects have nominal depths, widths, and lengths. The defects scanned with the sensing axis perpendicular to the defect length. Two parameters extracted from the GMR output voltage signal obtained, and a simple correlation between the defect’s dimensions and the GMR output voltage proposed.
      PubDate: Wed, 11 May 2022 00:00:00 +020
  • An Efficient Approximate Method for Scattering Response from Infinite
           Arrays of Nonlinearly Loaded Antenna in the Frequency Domain

    • Authors: S. R. Ostadzadeh; M. Salehi, B. Jafari
      Abstract: In this paper, different arrangements of infinite arrays of nonlinearly loaded antennas are analyzed in the frequency domain by an efficient approximate method and compared with the exact one which are respectively based on the nonlinear current and harmonic balance techniques. In one hand, although the exact method is suitable for strongly nonlinear load, it is suffering from gradient operation and initial guess in the iteration process especially under multi-tone excitations. On the other hand, although the approximate method is very efficient, it is limited to weakly nonlinear loads and low-valued incident waves. Finally, acceptable ranges for application of the approximate method versus different parameters such as nonlinearity effect of the load and the magnitude of incident wave are extracted.
      PubDate: Tue, 03 May 2022 00:00:00 +020
  • Study on Impact of Mutual Coupling on Performance of Dual Polarized Phased
           Array Antenna

    • Authors: S. Benny; S. Sahoo, A. Mukundan
      Abstract: This study involves the determination of the impact of mutual coupling between antenna elements on the performance of a dual-polarized, wide-angle scanning, phased array antenna for weather radar applications. Weather radars require dual linearly polarized antennas with low cross-polarization, and a narrow beam phased array for wide scanning angle. For this simulation-based study, a microstrip dual linearly polarized 2x20 phased array antenna operating at S-band (2.65 to 3.0 GHz) is designed. This antenna has been designed to have a cross-polarization level less than -45 dB at both polarizations and for the scan angle range of -55o to 55o, which is better than most of the existing dual-pol phased array antennas. This antenna has been used to analyze the impact of mutual coupling on cross-polarization, beamwidth, and antenna gain at various scan angles. Mutual coupling is studied in terms of antenna active element pattern and the corresponding cross-polarization value as well as the active reflection coefficient and impedance values for inter-element spacings of 0.4λ and 0.5λ. It has been found in this study that cross-polarization levels of the whole array (at various scan angles) are affected significantly because of mutual coupling between elements.
      PubDate: Mon, 02 May 2022 00:00:00 +020
  • A Low-Profile Hollow Waveguide Slot Array Antenna with Full-Corporate
           Feeding Network at K-Band

    • Authors: Y. E. Yamaç; A. Çalışkan, A. S. Türk, A. Kızılay
      Abstract: A hollow waveguide slot array antenna with a total of 338x106.5x28.9 mm3 is proposed as a sensor for radar applications at K-band. The proposed antenna consists of a radiating slot plate with 8x32 slots, a middle plate with 64 cavities and apertures, and a full-corporate-feeding network. The antenna is fabricated with these three parts in which the sub-array feeding technique is employed. The proposed antenna is designed for millimeter-wave short-range radar applications. For this purpose, the antenna radiates and achieves reasonable gain values between 23.72–25.30 GHz frequencies with 6.45% bandwidth. The measurement directivity is 32.1 dBi, and the realized gain of the antenna is measured as 30.83 dBi at 24.5 GHz center frequency with 74.8% total efficiency. The antenna achieves high gain and efficiency with straightforward fabrication. Although there are some fabrication errors and connector losses, antenna measurements are obtained sufficiently consistent with simulations.
      PubDate: Mon, 02 May 2022 00:00:00 +020
  • Compact 2-step Septulum Polarization Converters for Radars and Satellite

    • Authors: S. Piltyay; A. Bulashenko, I. Fesyuk, O. Bulashenko
      Abstract: This article presents the results of analysis, numerical simulations and optimization of new narrowband guide septulum polarization converters. Orthomode duplexers and polarization converter designs based on septulums are widely used in modern microwave systems with orthogonal circularly polarized signals. Septulum guide polarizer is an effective compact device, which transforms right-hand circularly polarized (RHCP) and left-hand circularly polarized (LHCP) electromagnetic modes into linearly polarized ones. At the same time it divides RHCP and LHCP modes and directs them to two different rectangular guides with high signal discrimination to each other. Thus, a septulum-based guide device integrates performance of a polarization transformer and of an orthomode duplexer. The main electromagnetic characteristics of the polarization converter were simulated in software based on the finite elements method in the frequency domain. The proposed design of a compact narrowband guide polarization converter has a septulum with two steps. Several designs of septulum polarization converters were developed and compared for different relative bandwidths of 5%, 10%, and 15%. The comparative investigation of the obtained designs was carried out. Main electromagnetic characteristics of optimal septulum polarization converters were compared. These include return losses, cross-polarization discrimination, ellipticity parameter, and ports discrimination. It was demonstrated that in 5% fractional bandwidth a compact 2-stepped septulum polarization converter has return losses greater than 22 dB. Its cross-polarization discrimination and ports discrimination are greater than 25 and 27 dB. Developed compact septulum polarization converters can be applied in modern antenna systems for radars and satellite communication systems.
      PubDate: Mon, 02 May 2022 00:00:00 +020
  • Highly Directive Array Pattern Synthesis in Different phi Planes of a
           Large CCRAA Using Array Thinning Technique

    • Authors: S. K. Dubey; D. Mandal, A. K. Mishra
      Abstract: This paper presents a pattern synthesis method of a sizeable concentric circular ring array (CCRAA) of isotropic antennas using Evolutionary Algorithms. In this method, the array is thinned using the optimum set of binary excitations to achieve the desired highly directive pencil beam patterns with lower peak side lobe level(SLL). The half-power beam width and first null beam width is kept constant to obtain such highly directive beam patterns with lower peak SLL. This pattern is not synthesized to a particular azimuth plane rather in four different ' planes from entire azimuth planes. The isotropic elements are uniformly spaced in the concentric ring. The achieved set of optimum amplitudes are constructed with either 1 or 0 using Differential Evolutionary Algorithm(DE), Genetic Algorithm (GA), and Particle Swarm Optimization Algorithm (PSO). These excitations show the state of the elements. The elements are in “ON” state or in “OFF” state depending upon the excitation ‘1’ or ‘0’. It is also helpful to reduce the complexity of the feed networks. The excitations are also verified in the whole range (0o <phi<360o) of ' planes by selecting four phi planes arbitrarily. The outcomes established the superiority of GA and DE over PSO and also the effectiveness of the proposed method.
      PubDate: Tue, 05 Apr 2022 00:00:00 +020
  • Design of Microstrip Tchebyscheff Phased Array Antennas for
           Inter-Vehicular Communication

    • Authors: J. S. Roy
      Abstract: To enhance the safety and comfort of a driver, the wireless technology is used for inter-vehicular communication (IVC). During the lane change in highways, the driver of a high speed vehicle can exploit the antenna technology using a microcontroller. Here, a 4-element Tchebyscheff phased array of microstrip antennas for IVC application is designed at millimeter wave frequency band of 60GHz. The details of this array design with feed network, its design layout and fabricated prototype are presented.  Another 4-element microstrip Tchebyscheff phased array for 6GHz IVC application is designed and the measured result is compared with the simulated result.
      PubDate: Sun, 03 Apr 2022 00:00:00 +020
  • Band Pass Negative Group Delay demonstration on a VHF RLC parallel passive
           lumped circuit

    • Authors: E. J. R. Sambatra; Y. C. Mombo Boussougou, Lucius Ramifidisoa, J.-P. Kouadio, S. Ngoho, A. Jaomiary, N. M. Murad
      Abstract: This paper demonstrates the bandpass (BP) negative group delay (NGD) function on a passive RLC-parallel lumped network at Very High Frequencies (VHF). After the topological description of the RLC cell, the BP NGD analysis is introduced. The NGD circuit is modelled theoretical by means of voltage transfer function (VTF) expression. The analytical equations illustrating the BP NGD specifications as the NGD center frequency, NGD value, NGD bandwidth and the VTF attenuation are established in function of the R, L and C component parameters. A proof of concept is designed, fabricated as a SMD on printed circuit board, and measured. As expected, the different models (calculated, simulated and measured) present a BP NGD and are significantly corelated. The POC prototype (resp the calculated and simulated model), presents an NGD value of - 8 ns (resp -12 ns) and attenuation of - 10 dB (resp -8 dB) around a 225 MHz (resp 240 MHz) NGD center frequency. Uncertainties analysis (UA) of BP NGD specifications is also studied in order to show the influence of quality and tolerance of components for NGD circuit. The theoretical formulas of NGD specification UAs in function of R, L and C tolerances are derived. UAs with respect to 1%, 2% and 5% relative tolerances of R, L and C components constituting the POC designed circuit are performed.
      PubDate: Fri, 18 Feb 2022 00:00:00 +010
  • Temporal Spectrum of a Scattered Electromagnetic Waves in the Conductive
           Collision Turbulent Magnetized Plasma

    • Authors: G. Jandieri; A. Ishimaru, B. Rawat, N. Tugushi
      Abstract: Using WKB method the peculiarities of the temporal spectrum of an ordinary and extraordinary electromagnetic wave scattered in a weakly randomly inhomogeneous three-dimensional nonstationary and conductive magnetized plasma are investigated. On the basis of the stochastic differential transport equation for the frequency fluctuation the broadening and the displacement of the temporal spectrum for both waves are obtained for the polar terrestrial ionosphere. These statistical characteristics contains anisotropic parameters: velocity of a plasma stream, conductivities of the ionosphere, elongated electron density irregularities are characterized by the anisotropy factor and inclination angle with respect to the geomagnetic lines of forces. The analysis of the power spectrum of the waves as a function of the propagation distance and the nondimensional frequency parameter containing the carrier frequency and characteristic temporal scale of electron density fluctuations are carried out. Analytical and numerical calculations have shown that the terrestrial conductivity and anisotropy factors exert a substantial influence on evaluation of the temporal spectrum than the inclination angle. It was found that the wave spectrum increases initially as the square root of the propagation distance, but at large distances it approaches a limiting value. Statistical moments of a scattered ordinary and extraordinary waves do not depend on an absorption sign and valid for both absorptive and active media.
      PubDate: Thu, 06 Jan 2022 00:00:00 +010
  • Exploring microwave absorption by non-periodic metasurfaces

    • Authors: J. K. Hamilton; I. R. Hooper, C. R. Lawrence
      Abstract: In recent years there has been a large body of work investigating periodic metasurface microwave absorbers. However, surprisingly few investigations have focused on the absorption performance of similar non-periodic designs. In this work, the electromagnetic response of a large area (310 mm x 310 mm) microwave absorber that lacks a global periodicity is experimentally studied. The top metallic layer of the ultra-thin (0.3 mm) absorber is structured with rectangular patches given by a procedurally generated non-periodic pattern, known as the toothpick sequence. The specular reflectivity of both p-polarised and s-polarised incident radiation shows coupling to an additional low frequency mode when compared to a standard square patch periodic absorber. To further explore the coupling efficiency of such non-periodic absorbers, finite element models were used to investigate the influence of increasing sample size.
      PubDate: Thu, 14 Oct 2021 00:00:00 +020
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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