ACES Publication Search
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| Title: | ACES Journal June 2021 Cover |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 2220 KB |
| Title: | ACES Journal June 2021 Front/Back Matter |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 12111 KB |
| Title: | ACES Journal June 2021 Full |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 32900 KB |
| Title: | Computational Performance of GTD-RT Applied for Evaluation of Electromagnetic Scattering on Rough Surfaces |
| Abstract: | In this paper, a new robust computational method that applies the geometrical theory of diffraction (GTD) in conjunction with the ray tracing (RT) technique is developed to evaluate the electromagnetic scattering pattern due to a plane wave represented as beam of parallel rays incident on a rough surface of quite arbitrary statistical parameters. The development of the proposed technique is explained in detail taking into consideration the generation of the geometrical model of the rough surface. The Fresnel reflection model is applied under the assumption of arbitrary electrical and optical properties of the rough surface material. Also the polarization of the plane wave primarily incident on the rough surface is taken into consideration. The algorithm developed in the present work accounts for multiple bounces of an incident ray and, hence, it can be considered arbitrary higher-order GTD-RT technique. The accuracy of the obtained results is verified through the comparison with the experimental measurements of the scattering pattern of a light beam incident on rough sheets with specific statistical properties. The numerical results of the present work are concerned with investigating the dependence of the scattering pattern on the surface roughness, refractive index, angle of incidence, and the resolution of the geometric model of the rough surface. Also, it is shown that, for limited resolution of the rough surface model, the accuracy of the calculated scattered field depends on the angle of incidence of the primary beam and the surface roughness. |
| Author(s): | A. E. Farahat, K. F. A. Hussein |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 2235 KB |
| Title: | Interpretation Method of GATEM Data based on PID Controller Iteration Downward Continuation Method |
| Abstract: | The Ground-source Airborne Time-domain Electromagnetic (GATEM) system has advantages for high efficiency and complex areas such as mountainous zone. Because of ignoring the impact of flight height, the section interpretation method seriously affects the interpretation and imaging accuracy of shallow anomalies. The PID controller iteration downward continuation method is proposed. Based on the original iteration continuation method, the differential coefficient and integral coefficient are added. The result shows that the new method remarkably decreases the iteration number, and the accuracy are verified by comparison with the numerical integration solution. The PID controller iteration downward continuation method is applied to the interpretation of GATEM data. For synthetic data, the interpretation results of continued electromagnetic response are closer to the true model than the z = 30 m interpretation results. The method is also applied to GATEM field data in Yangquan City, Shanxi Province, China. The interpretation results perform reliability using PID controller iteration downward continuation method in a GATEM field. |
| Author(s): | S. Guan, B. Du, D. Li, Y. Wang, Y. Zhu, Q. Wu, Y. Ji |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 2198 KB |
| Title: | The Behavior of Electromagnetic Wave Propagation in Photonic Crystals with or without a Defect |
| Abstract: | In this study, the electromagnetic wave propagation behavior of two-dimensional photonic crystal plates with a defect is investigated. For this purpose, the partial differential equation for the electromagnetic wave propagation in various photonic crystal plates containing a defect or not is obtained by using Maxwell’s equations. The defect is also defined in the electromagnetic wave propagation equation appropriately. In order to solve the electromagnetic wave propagation equation, the finite differences method is used. The material property parameters of the photonic crystal plates are determined with respect to the defects. Accordingly, the effects of material property parameters on electromagnetic wave propagation frequencies, phase velocities, and group velocities are examined. The effects of the size and position of the defects on the electromagnetic wave propagation frequencies are also discussed. The highest electromagnetic wave propagation fundamental frequency value obtained from the analyses performed is 1.198 Hz. This fundamental frequency value is obtained for the electromagnetic wave propagation in the t-shaped photonic crystal plate. Electromagnetic field distribution maps for the fundamental frequencies of the photonic crystal plates whose electromagnetic wave propagation behaviors are examined are obtained with the ANSYS package program based on the finite differences time-domain (FDTD) method. |
| Author(s): | A. N. Basmaci |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1878 KB |
| Title: | A Modified Hybrid Integral Equation to Electromagnetic Scattering from Composite PEC-Dielectric Objects Containing Closed-Open PEC Junctions |
| Abstract: | To efficiently analyze the electromagnetic scattering from composite perfect electric conductor (PEC)-dielectric objects with coexisting closed-open PEC junctions, a modified hybrid integral equation (HIE) is established as the surface integral equation (SIE) part of the volume surface integral equation (VSIE), which employs the combined field integral equation (CFIE) and the electric field integral equation (EFIE) on the closed and open PEC surfaces, respectively. Different from the traditional HIE modeled for the objects whose closed and open PEC surfaces are strictly separate, the modified HIE can be applied to the objects containing closed-open junctions. A matrix equation is obtained by using the Galerkin’s method of moments (MoM), which is augmented with the spherical harmonics expansion-based multilevel fast multipole algorithm (SE-MLFMA), improved by the mixed-potential representation and the triangle/tetrahedron-based grouping scheme. Because in the improved SE-MLFMA, the memory usage for storing the radiation patterns of basis functions is independent of the SIE type in the VSIE, it is highly appropriate for the fast solution of the VSIE that contains the HIE. Various numerical experiments demonstrate that during the calculation of composite objects containing closed-open PEC junctions, the application of the modified HIE in the VSIE can give reliable results with fast convergence speed. |
| Author(s): | J. Liu, H. Chen, H. Zhang, J. Yuan, Z. Li |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1359 KB |
| Title: | Gain Enhancement Planar Lens Antenna based on Wideband Focusing Gradient Meta-surface |
| Abstract: | A three-layered transmitting focusing gradient meta-surface (FGMS) has been proposed, which can achieve broadband gain enhancement from 8.2 GHz to 10 GHz. The element of broadband transmitting FGMS has high transmitting efficiencies that over 0.7 and achieve [0, 2π] phase range with a flat and linear trend in the operating band. The FGMS can transform the spherical waves into plane waves. Three patch antennas working at 8.2 GHz, 9.1 GHz, and 10 GHz respectively are placed the focus of broadband FGMS as the spherical-wave source to build a broadband planar lens antenna system. It achieves a simulation gain of 15.44 dBi which is 7.51dB higher than that of the bare patch antenna at 10 GHz with satisfying SLLs and beamwidths. However, it enhanced the gain of the bare patch antenna in a wide operating band. Finally, the FGMS and the patch antenna are fabricated and measured. The measured results are in good agreement with the simulations. |
| Author(s): | Q. Yu, S. Liu, Z. Huang, X. Kong, Y. Hu, Y. Wen |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 2164 KB |
| Title: | Design of Microstrip Parallel-Coupled Lines with High Directivity using Symmetric-Centered Inductors |
| Abstract: | A technique for directivity improvement of the microstrip parallel-coupled lines using symmetriccentered inductors is presented in this paper. The design procedure of the symmetric-centered inductors using the closed-form equations is given. The proposed technique was performed with a design at the operating frequency of 0.9 GHz on an FR4 substrate. Validity of the proposed technique is verified by simulations and measurements in comparisons with conventional parallel-coupled lines. The measured results exhibit the isolation of -30.10 dB and directivity of 19.28 dB at the operating frequency of 0.9 GHz. The directivity from the measured results is improved by more than 4 dB at 0.9 GHz and more than 6 dB at 1.05 GHz compared with the conventional parallel-coupled lines. In addition, the proposed technique for the microstrip parallel-coupled line can achieve a high directivity with the compact size (21.0 mm x 4.70 mm). The novelty of this paper is by introducing the proposed and closed-form design equations for the compact symmetric-centered inductors with high directivity. |
| Author(s): | S. Sonasang, N. Angkawisittpan |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1423 KB |
| Title: | Compact Dual-Passband Three-Dimensional FSS with Good Angular Stability and Both-Side Fast Roll-Off Characteristics |
| Abstract: | A compact dual-passband three-dimensional (3D) frequency selective surface (FSS) is proposed based on multiple square coaxial waveguides (SCWs), which exhibits good angular stability and both-side fast roll-off characteristics. The unit cell of the proposed 3D FSS is composed of one parallel plate waveguide (PPW) propagation path and two SCW propagation paths. By etching a centered annular slot, each SCW path forms two identical short SCWs. Each short SCW inherently generates one square slot resonance. In each SCW path, on the account of electromagnetic coupling between two square slot resonators provided by two short SCWs, the square slot resonant mode will split into even-/oddresonant modes. Accordingly, each SCW path can provide a flat second-order passband with two transmission poles. Due to the reflection and out of phase of electromagnetic waves, four transmission zeros located at both sides of the passbands are introduced for high frequency selectivity, realizing both-side fast roll-off performances. In order to explain the operating principle, the electricfield distributions at transmission-zero/pole frequencies are investigated. Finally, an FSS prototype is fabricated and measured, and the results exhibit good angular stability for both TE and TM polarizations under incident angles from 0° to 60°. In addition, the proposed 3D FSS has a compact unit cell. |
| Author(s): | Z. Yu, B. Li, S. Ding, W. Tang |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1567 KB |
| Title: | Development and Verification of Indirect Lightning-Induced Transient Protection Circuit for Avionics System |
| Abstract: | In this paper, an indirect lightning-induced transient protection circuit for avionics system is proposed, and its effectiveness is verified. The proposed circuit consists of a metal oxide varistor (MOV), a transient voltage suppression (TVS) diode, and a resistor. Compared with the conventional circuits (MOV or TVS diode), the improved noise suppression of the proposed circuit against indirect lightning strikes are experimentally verified in accordance with radio technical commission for aeronautics (RTCA) DO-160G Sec. 22. The highest attenuation levels of indirect lightning strike WF5A reference voltage and current signals are approximately 91.0% and approximately 98.4% for the input lightning signals, respectively. |
| Author(s): | S.-Y. Kim, J.-S. Park, W.-S. Lee |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1532 KB |
| Title: | Tunable Terahertz Plasmon-Induced Transparency in Resonator-Coupled Dirac Semimetal Waveguides |
| Abstract: | The bulk Dirac semimetal (BDS) is an interesting material, similar to graphene, which can dynamically adjust its optical properties via a variation in its Fermi energy or electrical voltage. In this work, a BDS-based plasmonic device, which enables tunable terahertz plasmon-induced transparency, was proposed and designed. By using the finite element method, the surface plasmon polariton and plasmon-induced transparency of this device were systematically investigated. The results demonstrate that the plasmoninduced transparency of such device can be dynamically tuned by varying its Fermi energy. When the Fermi energy changes from 55 meV to 95 meV, the maximum group delay time of the device increases from 13.2 ps to 21 ps. In the case of a cascading device, the maximum group delay time can be further pushed up to 44.57 ps. The influence of the ambient refractive index on the optical properties of the proposed device was also considered and investigated. |
| Author(s): | D. Wang, J. Yang, W. Wang, L. Yuan, X. Li |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1609 KB |
| Title: | On Electric Field Distribution and Temperature Rise Effect of High Power VLF Antenna |
| Abstract: | When a high-power very low frequency (VLF) communication system is in operation, the end of the antenna is in an alternating strong electric field environment. Due to dielectric loss, abnormal temperature rise may occur at the end of the antenna. To solve the problem, analysis on the electric field distribution and temperature rising effect at the end of the antenna is first carried out in this paper. The factors that affect the electric field distribution and temperature rising, including the amplitude and frequency of the excitation voltage, the diameter of the antenna conductor and the material properties of the outer sheath of the antenna, are studied in detail. A novel approach to improve the electric field distribution and to suppress temperature rising is proposed by designing a dielectric loss eliminator, and the effectiveness of the designed device is verified by simulation. |
| Author(s): | X. Li, K. Mao, A. Wang, J. Tian, W. Zhou |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1990 KB |
| Title: | Design and Analysis of a Triple-band Non-zonal Polarization Electromagnetic Metamaterial Absorber |
| Abstract: | A facile design of a novel triple-band electromagnetic metamaterial absorber (MMA) with polarization insensitive property is proposed in this paper. Each unit of the MMA consists of upper copper resonator and bottom copper plate with middle dielectric FR-4 between them. The MMA performs three absorption peaks at 16.919 GHz, 21.084 GHz and 25.266 GHz with absorption rates 99.90%, 97.76% and 99.18%, respectively. The influence of the main structural parameters on the frequencies and absorption rates is analyzed. The absorption mechanism of the absorber is explained by electric field, magnetic field and surface current distributions, which is supported by the electromagnetic parameters, affected with magnetic resonance. The polarization-insensitivity of TE wave is verified by observing the effects of the polarization angle change from 0-90º. The MMA can be applied in radiation, spectrum imaging detector, electromagnetic wave modulator, and so on. |
| Author(s): | H. Wu, S. Ji, J. Zhao, Z. Luo, H. Dai |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 2308 KB |
| Title: | Radiation Pattern Synthesis and Mutual Coupling Compensation in Spherical Conformal Array Antennas |
| Abstract: | This paper presents a novel technique based on Hybrid Spatial Distance Reduction Algorithm (HSDRA), to compensate the effects of deformity and mutual coupling occurred due to surface change in conformal arrays. This antenna surface deformation shifts the position of null points and loss of the main beam resulting in reduced antenna gain along with substantial undesirable effects on the antenna performance. The proposed algorithm, which cumulatively incorporates the Linearly Constraint Least Square Optimization (LCLSO) and Quadratically Constraint Least Square Optimization (QCLSO) techniques, is formulated to minimize/reduce the absolute distance between the actual (simulated/measured) radiation pattern and the desired radiation pattern while keeping the direction of mainbeam and nulls position under control. In particular, a 4x4 conformal microstrip phased array from planar surface is deformed to prescribe spherical-shape surface with various radii of curvature, is validated. For the enhancement of Gain of the conformal array antenna, Gain Maximization Algorithm is also proposed, the simulated results of which is compared to the traditional Phase compensation technique and unconstraint least squares optimization. The analytical results for both planar and spherical deformed configurations are first evaluated in MATLAB and then validated through Computer Simulation Technology (CST). |
| Author(s): | T. A. Khan, M. I. Khattak, A. Tariq |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1941 KB |
| Title: | Reduced Cross-Polarization Patch Antenna with Optimized Impedance Matching Using a Complimentary Split Ring Resonator and Slots as Defected Ground Structure |
| Abstract: | An innovative method is proposed to improve the cross-polarization performance and impedance matching of a microstrip antenna by integrating a complimentary split ring resonator and slots as a defected ground structure. An equivalent circuit model (ECM) enables the design take into consideration the mutual coupling between the antenna patch and the Defected Ground Structure. The input impedance and surface current density analysis confirms that the integration of a CSRR within a rectangular microstrip patch antennaleads to uniform comparative crosspolarization level below 40 dB in the H-plane, over an angular range of ± 50°. Introducing parallel slots, as well, leads to a reduction of spurious antenna radiation, thereby improving the impedance matching. Measurements conducted on a fabricated prototype are consistent with simulation results. The proposed antenna has a peak gain of 4.16 dB at 2.6 GHz resonating frequency, and hence is good candidate for broadband service applications. |
| Author(s): | N. RajeshKumar, P. D. Sathya, S. K. A. Rahim, A. A. Eteng |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1581 KB |
| Title: | Parameter Design of Conformal PML Based on 2D Monostatic RCS Optimization |
| Abstract: | In this study, 2D finite element (FE) solving process with the conformal perfectly matched layer (PML) is elucidated to perform the electromagnetic scattering computation. With the 2D monostatic RCS as the optimization objective, a sensitivity analysis of the basic design parameters of conformal PML (e.g., layer thickness, loss factor, extension order and layer number) is conducted to identify the major parameters of conformal PML that exerts more significant influence on 2D RCS. Lastly, the major design parameters of conformal PML are optimized by the simulated annealing algorithm (SA). As revealed from the numerical examples, the parameter design and optimization method of conformal PML based on SA is capable of enhancing the absorption effect exerted by the conformal PML and decreasing the error of the RCS calculation. It is anticipated that the parameter design method of conformal PML based on RCS optimization can be applied to the cognate absorbing boundary and 3D electromagnetic computation. |
| Author(s): | Y. J. Zhang, X. F. Deng |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1460 KB |
| Title: | Analysis and Development of an Efficient Cross-Slot Loaded Compact Electromagnetic Band Gap Antenna |
| Abstract: | This paper is devoted to a novel Electromagnetic Band Gap (EBG) single-feed circularly polarized microstrip EBG antenna with compact size proposed for C-Band applications. The antenna structure will include eight slits introduced at the boundary and the corners in the radiating square patch with a cross-slot at the center. The provided study will effectively approve the various proposed structures and interest occupied by these types of antennas in the enhancement of output parameters (gain, directivity, radiation efficiency, and bandwidth) without much affecting the operating bandwidth at C-band. At first, the concept and the realization of a directive and circularly polarized antenna using an electromagnetic band gap material whose circular polarization is generated by the structure itself is discussed. The analysis and simulation results are presented for an antenna operating at 6.1 GHz using computer Simulation Technologies (CST). Furthermore, the new compact circular polarized EBG antenna, compared to experimental results, will confirm the pre-studied goal of these kinds of antennas such as radiation efficiency, polarization purity, radiation efficiency, high directivity, and gain. |
| Author(s): | E. A. Hajlaoui, Z. M. Almohaimeed |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1421 KB |
| Title: | A Low-Profile Broadband Circularly Polarised Wide-Slot Antenna with an Artificial Magnetic Conductor Reflector |
| Abstract: | In this letter, a novel broadband circularly polarisation (CP) wide-slot antenna with an artificial magnetic conductor (AMC) as the reflector is presented. The wide-slot antenna is composed of a knife-shaped radiator and an improved ground plane. A broadband CP characteristic can be achieved by slotting the ground plane to make it an asymmetric ground shape. However, the average gain of the wide-slot antenna is only about 3 dBic because of bidirectional radiation. An AMC reflector is adopted to enhance the gain of the wide-slot antenna without introducing a high profile similar to the PEC reflector. In addition, the four metal plates are vertically placed around the antenna to broaden the axial ratio (AR) bandwidth of the antenna with the AMC reflector. The measurement results show that the 3dB AR bandwidth of the proposed CP antenna is 32.4% (2.35GHz─3.26GHz), the average gain is 6.5dBic in the AR bandwidth and the value of VSWR in the AR bandwidth is less than 2. The size of the antenna is 0.84λ0× 0.84λ0× 0.13λ0 at the centre frequency of 2.805 GHz. The proposed antenna has a low profile, broad AR bandwidth and high gain, thereby being a good candidate for various wireless communication systems. |
| Author(s): | F. Fan, X. Fan, X. Wang, Z. Yan |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1526 KB |
| Title: | Broadband CPW-Fed Circularly Polarized Square Slot Antenna for Universal UHF RFID Handheld Reader |
| Abstract: | This paper presents a new coplanar waveguide (CPW)-fed circularly polarized square slot antenna (CPSSA). The proposed antenna uses an inverted Z-shaped feedline protruded from the signal line of the feeding CPW. Circularly polarized (CP) radiation can be achieved by adequately inserting the arc-shaped grounded strip into the upper right corner of the square slot. The widened vertical tuning stub on the L-shaped grounded strip can improve impedance matching and axial ratio (AR) performance. The measured results indicate that the 10 dB impedance bandwidth is 620 MHz (652-1272 MHz), and the 3 dB axial ratio bandwidth is 320 MHz (840-1160 MHz), which has a broadband characteristic. In the range of the universal UHF RFID band, the measured peak gain is about 4.4 dBi. The proposed CPSSA uses low-cost FR4 material as the dielectric substrate. The overall size of the antenna is 119 × 119 × 0.5 mm3. The proposed antenna has a simple structure, easy processing, good performance, wide operating bandwidth, and dual circular polarization characteristic. It can be applied to the universal UHF RFID handheld reader environment. |
| Author(s): | R. Ma, Q. Feng |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1336 KB |
| Title: | Ultra-wideband Flexible Implantable Antenna for Wireless Capsule Endoscopy System with Performance Improvement |
| Abstract: | The implantable antenna is an important part of the wireless capsule endoscopy (WCE) system to achieve wireless communication. This paper designed an ultra-wideband flexible implantable antenna for wireless capsule endoscopy system. With a very wide bandwidth, the antenna can completely cover the industrial, scientific, and medical frequency bands (ISM, 2.4-2.48 GHz) and Wireless Medical Telemetry Service (WMTS, 1.395-1.4 GHz). The expanded size of the proposed antenna is 18mm× 10mm× 0.1mm. The conformal technology of the antenna has further reduced the space of the system and achieved miniaturization. The capsule antenna in this paper is a compact planar monopole antenna fed by a coplanar waveguide, and it uses a flexible material as a dielectric substrate to achieve the conformal shape of the antenna. U-shaped ground branch (UGB) and a loaded split ring resonator (SRR) structure were used to further improve the antenna performance. Simulation and measurement results were basically the same. On the premise of radiation safety and miniaturization of the antenna, the ultra-wideband operation of the antenna was realized. This antenna design provided reference value for the design and application of the capsule antenna. |
| Author(s): | Y. Feng, P. Chen, S. Pan, G. Li |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1325 KB |
| Title: | Compact 2x2 and 4x4 MIMO Antenna Systems for 5G Automotive Applications |
| Abstract: | In this paper, three Vehicular multiple-input multiple-output (MIMO) 5G antenna systems have been constructed from using a newly developed 5G cellular branched Monopole element are presented. The MIMO systems operates in the 5G frequency bands (617MHz- 5GHz) with a compact structure that allows for up to four elements to be integrated in the same Sharkfin. The 3 configurations of MIMO systems have been simulated using HFSS, measured on a 1-meter ground plane (GND), then measured on a vehicle roof and the individual antenna parameters in terms of reflection coefficient and efficiency have captured. The MIMO antenna systems performance in terms of passive isolation, combined radiation pattern, envelope correlation coefficient (ECC), and diversity gain (DG) have been reported and discussed. |
| Author(s): | M. O. Khalifa, A. M. Yacoub, D. N. Aloi |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 2454 KB |
| Title: | Complementary SRR-Based Reflector to Enhance Microstrip Antenna Performance |
| Abstract: | In this paper, complementary split ring resonator (SRR) based reflector to enhance the printed slot dipole (PSD) antenna performance is introduced. The numerically calculated return-loss, directivity and radiation pattern results of the PSD antenna, with (w/) and without (w/o) CSRR element etched on reflector plane are presented and investigated. Numerical analysis and modelling of the proposed design are carried out using CST Microwave Studio simulator based on the finite integration technique. According to the simulation results, with the inclusion of the CSRR-based reflector into the PSD antenna, the directivity is increased by values changes from 0.6 dB to 4.25 dB through the operation band, while an improvement in bandwidth (~2.1%) is seen. It is also shown that this improvement in antenna performance is due to the ε-negative (ENG) behavior of CSRR structures. Prototype of the proposed antenna is fabricated using Arlon DiClad 880 substrate with electrical permittivity of εr= 2.2. A quite good agreement between simulation and measurement is obtained. In this study, it is shown that the radiation performance of the antenna can be increased easily by using the CSRR element as a reflector in the antenna structure with a new enhancement approach. Also, the proposed antenna with a compact size of 0.27λ × 0.41λ is appropriate for operating in IEEE 802.11b/g/n/ax (2.4 GHz) WLAN applications. |
| Author(s): | M. H. B. Ucar |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1864 KB |
| Title: | Reconfigurable 2×1 CPW-Fed Rectangular Slot Antenna Array (RSAA) Based on Graphene for Wireless Communications |
| Abstract: | This article presents a 2×1 CPW ultra wideband rectangular slot antenna array (UWB-RSAA) with a modified circular slot shape to support a high data rate for wireless communications applications. The proposed antenna array dimensions are 0.7λo×0.8λo×0.064λo at the resonant frequency 1.8 GHz. It is fabricated on Rogers RO4003 substrate and fed by using a coplanar waveguide (CPW). A graphene layer is added on one side of the substrate to realize frequency reconfigurability and improve the array gain. The proposed array acquires -10 dB impedance bandwidth of the RSAA that extends from 1.7 GHz to 2.6 GHz, from 3.2 to 3.8 GHz, and from 5.2 GHz to 7 GHz. The proposed array achieved a realized peak gain of 7.5 dBi at 6.5 GHz at 0 Volt bias with an average gain of 4.5 dBi over the operating band. When the graphene bias is increased to 20 Volt, the antenna bandwidth extends from 1 GHz to 4 GHz and from 5 to 7 GHz with a peak gain of 14 dBi at 3.5 GHz and an average gain of 7.5 dBi. The linearly polarized operation of the proposed array over the operating bands makes it suitable for short-range wireless communications . |
| Author(s): | D. M. Elsheakh, O. M. Dardeer |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1678 KB |
| Title: | Improved Thevenin Equivalent Model of MMC Considering Pre-charge Conditions and DC Side Fault Conditions |
| Abstract: | The traditional Thevenin equivalent Modular Multilevel Converter (MMC) model has poor versatility for the two working conditions of pre-charging and DC-side faults. In this paper, an improved Thevenin equivalent MMC model considering pre-charge conditions and DC side fault conditions is proposed. The model divides the pre-charging condition into a Controllable charging stage and an Uncontrollable charging stage. The DC-side fault condition is divided into the pre-blocking and post-blocking conditions of the converter. The circuit characteristics are analyzed, and the equivalent model topology is comprehensively improved to make it suitable for full-condition simulation, and a control strategy suitable for the equivalent model is proposed. The detailed model and the proposed improved equivalent model were built in PSCAD/ EMTDC for comparison and analysis. The simulation results shows that the improved equivalent model can be applied to various working conditions, and the versatility of the traditional Thevenin equivalent model is improved |
| Author(s): | E. Jin, Z. Song, X. Yang, X. Yu |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1569 KB |
| Title: | Characteristic Analysis and Control of a Rotary Electromagnetic Eddy Current Brake |
| Abstract: | This article designs an electromagnetic rotating eddy current brake (ECB), which has the advantages of no wear and low noise compared with traditional friction brake. First, using the magnetic circuit analysis model, a theoretical calculation formula of the ECB’s braking characteristics is given. The results show that the braking torque is negatively correlated with the thickness of the air gap as well as the electrical conductivity and the relative magnetic permeability of the brake disc material, and positively correlated with the number of ampere turns and the number of electromagnet poles. Secondly, a three-dimensional finite element (FE) model of the brake is established. The results of braking torque-speed characteristics between finite element calculation and theoretical analysis are compared, and the reasons for the differences between the two are explained. Using the FE model, the influence of the design parameters on torque characteristics is studied. Combined with the theoretical analysis model, the results are explained accordingly, providing a reference for the optimal design of the brake. Finally, a controller for the electromagnetic rotating eddy current brake is designed to control the amplitude of the desired braking torque. |
| Author(s): | Q. Ren, J. Zhang, J. Luo |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1781 KB |
| Title: | Modeling the Microwave Transmissivity of Row Crops |
| Abstract: | We develop a method to model the microwave transmissivity of row crops that explicitly accounts for their periodic nature as well as multiple scattering. We hypothesize that this method could eventually be used to improve satellite retrieval of soil moisture and vegetation optical depth in agricultural regions. The method is characterized by unit cells terminated by periodic boundary conditions and Floquet port excitations solved using commercial software. Individual plants are represented by vertically oriented dielectric cylinders. We calculate canopy transmissivity, reflectivity, and loss in terms of S-parameters. We validate the model with analytical solutions and illustrate the effect of canopy scattering. Our simulation results are consistent with both simulated and measured data published in the literature. |
| Author(s): | J. Park, P. Gurrala, B. K. Hornbuckle, J. Song |
| File Type: | Journal Paper |
| Issue: | Volume: 36 Number: 6 Year: 2021 |
| Download Link: | Click here to download PDF File Size: 1726 KB |