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Publisher: Hindawi   (Total: 281 journals)

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Showing 1 - 200 of 281 Journals sorted alphabetically
Abstract and Applied Analysis     Open Access   (Followers: 3, SJR: 0.512, h-index: 32)
Active and Passive Electronic Components     Open Access   (Followers: 7, SJR: 0.157, h-index: 15)
Advances in Acoustics and Vibration     Open Access   (Followers: 33, SJR: 0.259, h-index: 6)
Advances in Aerospace Engineering     Open Access   (Followers: 52)
Advances in Agriculture     Open Access   (Followers: 8)
Advances in Artificial Intelligence     Open Access   (Followers: 15)
Advances in Astronomy     Open Access   (Followers: 33, SJR: 0.351, h-index: 17)
Advances in Bioinformatics     Open Access   (Followers: 17, SJR: 0.421, h-index: 8)
Advances in Chemistry     Open Access   (Followers: 20)
Advances in Civil Engineering     Open Access   (Followers: 37, SJR: 0.338, h-index: 8)
Advances in Condensed Matter Physics     Open Access   (Followers: 10, SJR: 0.248, h-index: 10)
Advances in Decision Sciences     Open Access   (Followers: 3, SJR: 0.231, h-index: 6)
Advances in Electronics     Open Access   (Followers: 63)
Advances in Fuzzy Systems     Open Access   (Followers: 5, SJR: 0.258, h-index: 7)
Advances in Hematology     Open Access   (Followers: 10, SJR: 0.892, h-index: 18)
Advances in High Energy Physics     Open Access   (Followers: 18, SJR: 0.892, h-index: 19)
Advances in Human-Computer Interaction     Open Access   (Followers: 19, SJR: 0.439, h-index: 9)
Advances in Materials Science and Engineering     Open Access   (Followers: 30, SJR: 0.263, h-index: 11)
Advances in Mathematical Physics     Open Access   (Followers: 3, SJR: 0.332, h-index: 10)
Advances in Medicine     Open Access   (Followers: 2)
Advances in Meteorology     Open Access   (Followers: 19, SJR: 0.498, h-index: 10)
Advances in Multimedia     Open Access   (Followers: 1, SJR: 0.191, h-index: 10)
Advances in Nonlinear Optics     Open Access   (Followers: 6)
Advances in Numerical Analysis     Open Access   (Followers: 4)
Advances in Nursing     Open Access   (Followers: 27)
Advances in Operations Research     Open Access   (Followers: 12, SJR: 0.343, h-index: 7)
Advances in Optical Technologies     Open Access   (Followers: 3, SJR: 0.283, h-index: 16)
Advances in OptoElectronics     Open Access   (Followers: 5, SJR: 0.973, h-index: 16)
Advances in Orthopedics     Open Access   (Followers: 8)
Advances in Pharmacological Sciences     Open Access   (Followers: 7, SJR: 0.695, h-index: 13)
Advances in Physical Chemistry     Open Access   (Followers: 9, SJR: 0.297, h-index: 7)
Advances in Power Electronics     Open Access   (Followers: 29, SJR: 0.26, h-index: 6)
Advances in Preventive Medicine     Open Access   (Followers: 5)
Advances in Public Health     Open Access   (Followers: 24)
Advances in Software Engineering     Open Access   (Followers: 10)
Advances in Tribology     Open Access   (Followers: 12, SJR: 0.267, h-index: 6)
Advances in Urology     Open Access   (Followers: 9, SJR: 0.629, h-index: 16)
Advances in Virology     Open Access   (Followers: 7, SJR: 1.04, h-index: 12)
AIDS Research and Treatment     Open Access   (Followers: 3, SJR: 1.125, h-index: 14)
Analytical Cellular Pathology     Open Access   (Followers: 2, SJR: 0.334, h-index: 12)
Anatomy Research Intl.     Open Access   (Followers: 2)
Anemia     Open Access   (Followers: 5, SJR: 0.991, h-index: 11)
Anesthesiology Research and Practice     Open Access   (Followers: 13, SJR: 0.513, h-index: 12)
Applied and Environmental Soil Science     Open Access   (Followers: 16, SJR: 0.53, h-index: 9)
Applied Bionics and Biomechanics     Open Access   (Followers: 8, SJR: 0.23, h-index: 13)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Archaea     Open Access   (Followers: 3, SJR: 1.248, h-index: 27)
Arthritis     Open Access   (Followers: 5)
Autism Research and Treatment     Open Access   (Followers: 25)
Autoimmune Diseases     Open Access   (Followers: 3, SJR: 0.909, h-index: 17)
Behavioural Neurology     Open Access   (Followers: 9, SJR: 0.696, h-index: 34)
Biochemistry Research Intl.     Open Access   (Followers: 6, SJR: 1.085, h-index: 17)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9, SJR: 0.286, h-index: 19)
BioMed Research Intl.     Open Access   (Followers: 4, SJR: 0.725, h-index: 59)
Biotechnology Research Intl.     Open Access   (Followers: 1)
Bone Marrow Research     Open Access   (Followers: 2)
Canadian J. of Gastroenterology & Hepatology     Open Access   (Followers: 5, SJR: 0.856, h-index: 53)
Canadian J. of Infectious Diseases and Medical Microbiology     Open Access   (Followers: 5, SJR: 0.409, h-index: 25)
Canadian Respiratory J.     Open Access   (Followers: 1, SJR: 0.503, h-index: 42)
Cardiology Research and Practice     Open Access   (Followers: 8, SJR: 0.941, h-index: 17)
Case Reports in Anesthesiology     Open Access   (Followers: 10)
Case Reports in Cardiology     Open Access   (Followers: 3)
Case Reports in Critical Care     Open Access   (Followers: 8)
Case Reports in Dentistry     Open Access   (Followers: 5)
Case Reports in Dermatological Medicine     Open Access   (Followers: 2)
Case Reports in Emergency Medicine     Open Access   (Followers: 14)
Case Reports in Endocrinology     Open Access   (Followers: 1, SJR: 0.326, h-index: 1)
Case Reports in Gastrointestinal Medicine     Open Access   (Followers: 2)
Case Reports in Genetics     Open Access   (Followers: 1)
Case Reports in Hematology     Open Access   (Followers: 5)
Case Reports in Hepatology     Open Access   (Followers: 1)
Case Reports in Immunology     Open Access   (Followers: 4)
Case Reports in Infectious Diseases     Open Access   (Followers: 5)
Case Reports in Medicine     Open Access   (Followers: 2)
Case Reports in Nephrology     Open Access   (Followers: 4)
Case Reports in Neurological Medicine     Open Access   (Followers: 1)
Case Reports in Obstetrics and Gynecology     Open Access   (Followers: 10)
Case Reports in Oncological Medicine     Open Access   (Followers: 2)
Case Reports in Ophthalmological Medicine     Open Access   (Followers: 3)
Case Reports in Orthopedics     Open Access   (Followers: 5)
Case Reports in Otolaryngology     Open Access   (Followers: 6)
Case Reports in Pathology     Open Access   (Followers: 5)
Case Reports in Pediatrics     Open Access   (Followers: 6)
Case Reports in Psychiatry     Open Access   (Followers: 12)
Case Reports in Pulmonology     Open Access   (Followers: 3)
Case Reports in Radiology     Open Access   (Followers: 8)
Case Reports in Rheumatology     Open Access   (Followers: 5)
Case Reports in Surgery     Open Access   (Followers: 11)
Case Reports in Transplantation     Open Access  
Case Reports in Urology     Open Access   (Followers: 8)
Case Reports in Vascular Medicine     Open Access  
Case Reports in Veterinary Medicine     Open Access   (Followers: 6)
Child Development Research     Open Access   (Followers: 16)
Chinese J. of Engineering     Open Access   (Followers: 2)
Chinese J. of Mathematics     Open Access  
Cholesterol     Open Access   (Followers: 1, SJR: 0.906, h-index: 12)
Chromatography Research Intl.     Open Access   (Followers: 6)
Complexity     Hybrid Journal   (Followers: 6, SJR: 0.526, h-index: 27)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2, SJR: 0.415, h-index: 22)
Computational Intelligence and Neuroscience     Open Access   (Followers: 10, SJR: 0.232, h-index: 30)
Contrast Media & Molecular Imaging     Open Access   (Followers: 3, SJR: 0.932, h-index: 34)
Critical Care Research and Practice     Open Access   (Followers: 10, SJR: 0.916, h-index: 14)
Current Gerontology and Geriatrics Research     Open Access   (Followers: 9, SJR: 0.8, h-index: 12)
Depression Research and Treatment     Open Access   (Followers: 13, SJR: 0.77, h-index: 11)
Dermatology Research and Practice     Open Access   (Followers: 3, SJR: 0.576, h-index: 15)
Diagnostic and Therapeutic Endoscopy     Open Access   (SJR: 0.651, h-index: 18)
Discrete Dynamics in Nature and Society     Open Access   (Followers: 5, SJR: 0.323, h-index: 24)
Disease Markers     Open Access   (Followers: 1, SJR: 0.774, h-index: 49)
Education Research Intl.     Open Access   (Followers: 19)
Emergency Medicine Intl.     Open Access   (Followers: 7)
Enzyme Research     Open Access   (Followers: 3, SJR: 0.457, h-index: 18)
Evidence-based Complementary and Alternative Medicine     Open Access   (Followers: 20, SJR: 0.615, h-index: 50)
Experimental Diabetes Research     Open Access   (Followers: 14, SJR: 1.591, h-index: 30)
Gastroenterology Research and Practice     Open Access   (Followers: 2, SJR: 0.664, h-index: 21)
Genetics Research Intl.     Open Access   (Followers: 1)
Geofluids     Open Access   (Followers: 4, SJR: 0.693, h-index: 38)
HPB Surgery     Open Access   (Followers: 4, SJR: 0.798, h-index: 22)
Infectious Diseases in Obstetrics and Gynecology     Open Access   (Followers: 5, SJR: 0.976, h-index: 34)
Interdisciplinary Perspectives on Infectious Diseases     Open Access   (Followers: 1, SJR: 0.763, h-index: 15)
Intl. J. of Aerospace Engineering     Open Access   (Followers: 71, SJR: 0.241, h-index: 6)
Intl. J. of Agronomy     Open Access   (Followers: 5, SJR: 0.223, h-index: 2)
Intl. J. of Alzheimer's Disease     Open Access   (Followers: 11, SJR: 1.193, h-index: 25)
Intl. J. of Analysis     Open Access  
Intl. J. of Analytical Chemistry     Open Access   (Followers: 20, SJR: 0.157, h-index: 2)
Intl. J. of Antennas and Propagation     Open Access   (Followers: 11, SJR: 0.385, h-index: 15)
Intl. J. of Atmospheric Sciences     Open Access   (Followers: 21)
Intl. J. of Biodiversity     Open Access   (Followers: 4)
Intl. J. of Biomaterials     Open Access   (Followers: 4, SJR: 0.485, h-index: 10)
Intl. J. of Biomedical Imaging     Open Access   (Followers: 3, SJR: 0.581, h-index: 23)
Intl. J. of Breast Cancer     Open Access   (Followers: 13)
Intl. J. of Cell Biology     Open Access   (Followers: 3, SJR: 2.658, h-index: 25)
Intl. J. of Chemical Engineering     Open Access   (Followers: 7, SJR: 0.361, h-index: 10)
Intl. J. of Chronic Diseases     Open Access   (Followers: 1)
Intl. J. of Computer Games Technology     Open Access   (Followers: 9, SJR: 0.213, h-index: 12)
Intl. J. of Corrosion     Open Access   (Followers: 10, SJR: 0.19, h-index: 7)
Intl. J. of Dentistry     Open Access   (Followers: 6, SJR: 0.558, h-index: 11)
Intl. J. of Differential Equations     Open Access   (Followers: 7, SJR: 0.363, h-index: 11)
Intl. J. of Digital Multimedia Broadcasting     Open Access   (Followers: 5, SJR: 0.144, h-index: 10)
Intl. J. of Electrochemistry     Open Access   (Followers: 8)
Intl. J. of Endocrinology     Open Access   (Followers: 3, SJR: 0.961, h-index: 24)
Intl. J. of Engineering Mathematics     Open Access   (Followers: 5)
Intl. J. of Food Science     Open Access   (Followers: 3)
Intl. J. of Forestry Research     Open Access   (Followers: 3)
Intl. J. of Genomics     Open Access   (Followers: 2, SJR: 0.721, h-index: 7)
Intl. J. of Hepatology     Open Access   (Followers: 4)
Intl. J. of Hypertension     Open Access   (Followers: 6, SJR: 0.823, h-index: 20)
Intl. J. of Inflammation     Open Access   (SJR: 0.876, h-index: 14)
Intl. J. of Mathematics and Mathematical Sciences     Open Access   (Followers: 3, SJR: 0.346, h-index: 27)
Intl. J. of Medicinal Chemistry     Open Access   (Followers: 5)
Intl. J. of Microbiology     Open Access   (Followers: 4, SJR: 1.006, h-index: 18)
Intl. J. of Navigation and Observation     Open Access   (Followers: 20, SJR: 0.411, h-index: 7)
Intl. J. of Nephrology     Open Access   (Followers: 1, SJR: 0.926, h-index: 14)
Intl. J. of Optics     Open Access   (Followers: 7, SJR: 0.262, h-index: 7)
Intl. J. of Otolaryngology     Open Access   (Followers: 3)
Intl. J. of Pediatrics     Open Access   (Followers: 5)
Intl. J. of Peptides     Open Access   (Followers: 4, SJR: 0.73, h-index: 16)
Intl. J. of Photoenergy     Open Access   (Followers: 2, SJR: 0.348, h-index: 28)
Intl. J. of Plant Genomics     Open Access   (Followers: 4, SJR: 1.578, h-index: 20)
Intl. J. of Polymer Science     Open Access   (Followers: 24, SJR: 0.265, h-index: 11)
Intl. J. of Population Research     Open Access   (Followers: 2)
Intl. J. of Quality, Statistics, and Reliability     Open Access   (Followers: 15, SJR: 0.345, h-index: 4)
Intl. J. of Reconfigurable Computing     Open Access   (SJR: 0.182, h-index: 8)
Intl. J. of Reproductive Medicine     Open Access   (Followers: 4)
Intl. J. of Rheumatology     Open Access   (Followers: 4, SJR: 1.015, h-index: 18)
Intl. J. of Rotating Machinery     Open Access   (Followers: 2, SJR: 0.402, h-index: 19)
Intl. J. of Spectroscopy     Open Access   (Followers: 6)
Intl. J. of Stochastic Analysis     Open Access   (Followers: 3, SJR: 0.234, h-index: 19)
Intl. J. of Surgical Oncology     Open Access   (Followers: 1, SJR: 0.753, h-index: 11)
Intl. J. of Telemedicine and Applications     Open Access   (Followers: 4, SJR: 0.757, h-index: 14)
Intl. J. of Vascular Medicine     Open Access   (SJR: 0.865, h-index: 16)
Intl. J. of Zoology     Open Access   (Followers: 1, SJR: 0.389, h-index: 8)
Intl. Scholarly Research Notices     Open Access   (Followers: 190)
ISRN Astronomy and Astrophysics     Open Access   (Followers: 6)
J. of Addiction     Open Access   (Followers: 12)
J. of Advanced Transportation     Hybrid Journal   (Followers: 12, SJR: 0.911, h-index: 24)
J. of Aging Research     Open Access   (Followers: 6, SJR: 1.259, h-index: 23)
J. of Analytical Methods in Chemistry     Open Access   (Followers: 1, SJR: 0.296, h-index: 13)
J. of Applied Chemistry     Open Access   (Followers: 4)
J. of Applied Mathematics     Open Access   (Followers: 2, SJR: 0.341, h-index: 22)
J. of Biomedical Education     Open Access   (Followers: 3)
J. of Blood Transfusion     Open Access   (Followers: 1)
J. of Botany     Open Access   (Followers: 3, SJR: 0.101, h-index: 2)
J. of Cancer Epidemiology     Open Access   (Followers: 5, SJR: 1.427, h-index: 12)
J. of Chemistry     Open Access   (Followers: 5, SJR: 0.225, h-index: 11)
J. of Combustion     Open Access   (Followers: 22, SJR: 0.27, h-index: 8)
J. of Complex Analysis     Open Access   (Followers: 3)
J. of Composites     Open Access   (Followers: 80)
J. of Computer Networks and Communications     Open Access   (Followers: 4, SJR: 0.257, h-index: 8)
J. of Construction Engineering     Open Access   (Followers: 8)
J. of Control Science and Engineering     Open Access   (Followers: 1, SJR: 0.299, h-index: 9)
J. of Diabetes Research     Open Access   (Followers: 12, SJR: 1.024, h-index: 13)
J. of Drug Delivery     Open Access   (Followers: 6, SJR: 4.523, h-index: 2)
J. of Electrical and Computer Engineering     Open Access   (Followers: 9, SJR: 0.225, h-index: 10)
J. of Energy     Open Access   (Followers: 2)
J. of Engineering     Open Access  
J. of Environmental and Public Health     Open Access   (Followers: 15, SJR: 1.136, h-index: 16)
J. of Food Quality     Hybrid Journal   (Followers: 7, SJR: 0.497, h-index: 30)
J. of Function Spaces     Open Access   (SJR: 0.414, h-index: 10)
J. of Geological Research     Open Access   (Followers: 1)
J. of Healthcare Engineering     Open Access   (Followers: 3, SJR: 0.345, h-index: 10)

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Journal Cover International Journal of Antennas and Propagation
  [SJR: 0.385]   [H-I: 15]   [11 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Print) 1687-5869 - ISSN (Online) 1687-5877
   Published by Hindawi Homepage  [281 journals]
  • A Literature Survey on Wireless Power Transfer for Biomedical Devices

    • Abstract: This paper provides a review and survey of research on power transfer for biomedical applications based on inductive coupling. There is interest in wireless power transfer (WPT) for implantable and wearable biomedical devices, for example, heart pacemaker or implantable electrocardiogram (ECG) recorders. This paper concentrates on the applications based on near-field power transfer methods, summarizes the main design features in the recent literature, and provides some information about the system model and coil optimization.
      PubDate: Thu, 12 Apr 2018 09:11:55 +000
       
  • The Application of Improved Spherical Harmonics Expansion-Based Multilevel
           Fast Multipole Algorithm in the Solution of Volume-Surface Integral
           Equation

    • Abstract: During the solution of volume-surface integral equation (VSIE), to reduce the core memory requirement of the radiation patterns (RPs) of the basis functions, an improved spherical harmonics expansion-based multilevel fast multipole algorithm (SE-MLFMA) using the mixed-potential representation and the triangle-/tetrahedron-based grouping scheme is applied. Numerical results show that accompanying with a faster speed, the memory requirement of the RPs in the improved SE-MLFMA is several times less than that in the conventional MLFMA without compromising accuracy. A result employing the OpenMP parallelization and vector arithmetic logic unit (VALU) hardware acceleration technique is also shown to illustrate the robustness and scalability of the improved SE-MLFMA method.
      PubDate: Wed, 11 Apr 2018 00:00:00 +000
       
  • Study on the Relationships between Eigenmodes, Natural Modes, and
           Characteristic Modes of Perfectly Electric Conducting Bodies

    • Abstract: We specify the corresponding relationships between eigenmodes, natural modes, and characteristic modes of perfectly electric conducting (PEC) bodies. The internal resonant frequencies, external resonant frequencies, current distributions, and radiation patterns of the three kinds of modes are compared to identify the relationships. Firstly, we review the definitions of the three kinds of modes and discuss their characteristics of the electromagnetic power. After that, we illustrate the relationships between these modes with three typical structures, that is, the infinite circular cylinder, sphere, and rectangular plate.
      PubDate: Tue, 10 Apr 2018 00:00:00 +000
       
  • An Extended Newmark-FDTD Method for Complex Dispersive Media

    • Abstract: Based on polarizability in the form of a complex quadratic rational function, a novel finite-difference time-domain (FDTD) approach combined with the Newmark algorithm is presented for dealing with a complex dispersive medium. In this paper, the time-stepping equation of the polarization vector is derived by applying simultaneously the Newmark algorithm to the two sides of a second-order time-domain differential equation obtained from the relation between the polarization vector and electric field intensity in the frequency domain by the inverse Fourier transform. Then, its accuracy and stability are discussed from the two aspects of theoretical analysis and numerical computation. It is observed that this method possesses the advantages of high accuracy, high stability, and a wide application scope and can thus be applied to the treatment of many complex dispersion models, including the complex conjugate pole residue model, critical point model, modified Lorentz model, and complex quadratic rational function.
      PubDate: Tue, 10 Apr 2018 00:00:00 +000
       
  • Design of a Suspended Stripline Narrow Bandpass Filter with Ultrawideband
           Harmonic Suppression

    • Abstract: A design method of narrow bandpass filters (NBPFs) of 4–6% bandwidth with ultrawideband suppression of harmonic passbands, utilizing two cascaded step impedance resonators (SIRs) in a suspended stripline, is proposed in this paper. The proposed design utilized the characteristics of a suspended stripline, which provides a much higher characteristic impedance ratio as compared with that of the microstripline, enabling ultrawideband harmonic suppression. As an example of the NBPF, a filter with a passband center frequency of 0.75 GHz and bandwidth of 5% was implemented and proved to suppress the harmonic passbands up to . Since the proposed filter was implemented on the suspended stripline, the passband insertion loss was only −0.9 dB, which is low as compared with other previous designs. The proposed filter is a compact high-performance low-loss NBPF, which can be applicable to various wireless systems.
      PubDate: Thu, 05 Apr 2018 00:00:00 +000
       
  • Design of the Variable Inclination Continuous Transverse Stub Antenna
           Based on Rectangular Grating Slow-Wave Structure

    • Abstract: In order to solve difficulty in designing nonlinear slow-wave structure (SWS) of the variable inclination continuous transverse stub (VICTS) antenna, we combine the study of the semiopen rectangular grating SWS in the PPW with equivalent circuit theory of leaky-wave antenna to propose a theoretical model for SWS of VICTS element. The computations that the propagation characteristics of VICTS element are calculated by the theoretical model. The results are consistent with the full-wave simulation, which prove the validity and accuracy of the theoretical model. Lastly, by using the theoretical model, an approach for nonlinearly designing SWS is introduced and carried out. The approach improves the gain of the VICTS antenna 0.4 dB.
      PubDate: Mon, 02 Apr 2018 05:46:43 +000
       
  • Analysis of Electromagnetic Propagation from MHz to THz with a
           Memory-Optimised CPML-FDTD Algorithm

    • Abstract: FDTD method opened a fertile research area on the numerical analysis of electromagnetic phenomena under a wide range of media and propagation conditions, providing an extensive analysis of electromagnetic behaviour like propagation, reflection, refraction, and multitrajectory phenomena. In this paper, we present an optimised FDTD-CPML algorithm, focused in saving memory while increasing the performance of the algorithm. We particularly implement FDTD-CPML method at high frequency bands, used in several telecommunications applications as well as in nanoelectromagnetism. We show an analysis of the performance of the algorithm in single and double precision, as well as a stability of the algorithm analysis, from where we conclude that the implemented CPML ABC constitutes a robust choice in terms of precision and accuracy for the high frequencies herein considered. It is important to recall that the CPML ABC parameters provided in this paper are fixed for the tested range of frequencies, that is, from MHz to THz.
      PubDate: Mon, 02 Apr 2018 00:00:00 +000
       
  • Parabolic Equation Accumulated Split Error and Its Correction Method for
           Tropospheric Radio Propagation

    • Abstract: An increasingly popular approach of modeling electromagnetic wave propagation in the troposphere is to use the slip-step Fourier transform (SSFT) numerical algorithm to solve a parabolic equation (PE). However, available SSFT does not provide perfect solutions by introducing accumulated split error (ASE) for its step-by-step iteration process with a fixed propagation range step. The common analysis on one step split error is only a simple discussion on the split error of PE. Therefore, the main motivation of this study is to provide improvement on the accuracy of the PE by proposing an error correction method for the first time in the literature for PE. This method is on the basis of defining and deriving the accumulated split error. Its performance is then demonstrated with measured radar sea clutter data from Huanghai Sea, China.
      PubDate: Mon, 02 Apr 2018 00:00:00 +000
       
  • Investigating Equations Used to Design a Very Small Normal-Mode Helical
           Antenna in Free Space

    • Abstract: A normal-mode helical antenna (NMHA) has been applied in some small devices such as tire pressure monitoring systems (TPMS) and radio frequency identification (RFID) tags. Previously, electrical characteristics of NMHA were obtained through electromagnetic simulations. In practical design of NMHA, equational expressions for the main electrical characteristics are more convenient. Electrical performances of NMHA can be expressed by a combination of a short dipole and small loops. Applicability of equations for a short dipole and a small loop to very small normal-mode helical antennas such as antennas around 1/100 wavelengths was not clear. In this paper, accuracies of equations for input resistances, antenna efficiency, and axial ratios are verified by comparisons with electromagnetic simulation results by FEKO software at 402 MHz. In addition, the structure of the antenna equal to 0.021 λ is fabricated, and measurements are performed to confirm the design accuracy.
      PubDate: Mon, 02 Apr 2018 00:00:00 +000
       
  • Vehicle-to-Vehicle Radio Channel Characteristics for Congestion Scenario
           in Dense Urban Region at 5.9 GHz

    • Abstract: This paper reports the results of a car-following measurement of the wireless propagation channel at 5.9 GHz on a seriously congested urban road in Wuhan, China. The small-scale amplitude-fading distribution was determined to be a Ricean distribution using the Akaike information criterion. This result shows that this car-following scenario can be regarded as a line-of-sight radio channel. Moreover, the statistical K-factor features follow a Gaussian distribution. According to the power delay profile and average power delay profile, we found that street buildings in this dense urban environment contributed to very strong reflection phenomena. The impact of a powerful reflection is analyzed through path loss, delay, and Doppler spreads in the channel statistical properties. In the frequency domain, we observe a U-shape delay-Doppler spectrum that proved that the dense urban scenario consists of scattering channels. All these results are summarized in tabular form that will be useful in the modeling of vehicle-to-vehicle wireless communication systems.
      PubDate: Sun, 01 Apr 2018 00:00:00 +000
       
  • Finite-Difference Time Domain Techniques Applied to Electromagnetic Wave
           Interactions with Inhomogeneous Plasma Structures

    • Abstract: Motivated by the emerging field of plasma antennas, electromagnetic wave propagation in and scattering by inhomogeneous plasma structures are studied through finite-difference time domain (FDTD) techniques. These techniques have been widely used in the past to study propagation near or through the ionosphere, and their extension to plasma devices such as antenna elements is a natural development. Simulation results in this work are validated with comparisons to solutions obtained by eigenfunction expansion techniques well supported by the literature and are shown to have an excellent agreement. The advantages of using FDTD simulations for this type of investigation are also outlined; in particular, FDTD simulations allow for field solutions to be developed at lower computational cost and greater resolution than equivalent eigenfunction methods for inhomogeneous plasmas and are applicable to arbitrary plasma properties such as spatially or time-varying inhomogeneities and collision frequencies, as well as allowing transient effects to be studied as the field solutions are obtained in the time domain.
      PubDate: Thu, 29 Mar 2018 00:00:00 +000
       
  • Active Surface Compensation for Large Radio Telescope Antennas

    • Abstract: With the development of radio telescope antennas with large apertures, high gain, and wide frequency bands, compensation methods, such as mechanical or electronic compensation, are obviously essential to ensure the electrical performance of antennas that work in complex environments. Since traditional compensation methods can only adjust antenna pointing but not the surface accuracy, which are limited for obtaining high surface precision and aperture efficiency, active surface adjustment has become an indispensable tool in this field. Therefore, the development process of electrical performance compensation methods for radio telescope antennas is introduced. Further, a series of analyses of the five key technologies of active surface adjustment is presented. Then, four typical large antennas that have been designed with active main reflector technology are presented and compared. Finally, future research directions and suggestions for reflector antenna compensation methods based on active surface adjustment are presented.
      PubDate: Thu, 29 Mar 2018 00:00:00 +000
       
  • Analysis and Synthesis of Double Negative Dielectric Media Rectenna
           Systems for Ambient Microwave Energy Harvesting

    • Abstract: The concept of harvesting the ambient electromagnetic radiation energy, coming from public telecommunication wireless networks, has been recently subject of extensive research. Techniques proposed for this target use mainly antennas, as the grade gathering the radiation power. In this work, a method introducing the usage of specific dielectric structures with artificially negative electric permittivity and magnetic permeability (double negative media or DNG) in combination with wire dipole antenna sensors is proposed as an RF harvesting system. Theoretical study of the synthesized DNG medium’s performance and the distribution of the electromagnetic field in its interior is made, with the intention of finding the areas of maximum electric field intensity at which the antenna sensors would be positioned for maximum power scavenging. The received numerical results show that the synthesized schemes are capable of enhancing the energy gathering ability. Compared to the same antenna sensors positioned in free space, they ensure higher input voltage to the rectifier and also an increase of the available power about 10 dB. Moreover, they exhibit this performance for every direction of arrival of the incoming waves. The hybrid schemes DNG dipole antenna were designed for the Universal Mobile Telecommunication System (UMTS) frequency band, but the method is general and would be applied to any other frequency band and also with other antenna types.
      PubDate: Wed, 28 Mar 2018 06:22:31 +000
       
  • Inkjet-Printed Flexible MEMS Switches for Phased-Array Antennas

    • Abstract: This paper presents a fully inkjet-printed flexible MEMS switch for phased-array antennas. The physical structure of the printed MEMS switch consists of an anchor with a clamp-clamp beam, a sacrificial layer, and bottom transmission lines. 5-mil Kapton® polyimide film is used as a flexible substrate material. Two different types of conductive ink PEDOT : PSS from Sigma Aldrich and silver nanoparticle ink from NovaCentrix are used for the fabrication of different printed layers. Layer-by-layer fabrication process and material evaluation are illustrated. Layer characterization is done with respect to critical thickness and resistance using 2D/3D material analysis. Fujifilm Dimatix Material Printer (DMP-2800) is used for fabrication, and KLA-Tencor (P-7) profiler is used for 2D and 3D analysis of each layer. The MEMS switch has a low actuation voltage of 1.2 V, current capacity of 0.2195 mA, a current on-off ratio of 2195 : 1, and an RF insertion loss of 5 dB up to 13.5 GHz. Printed MEMS switch technology is a promising candidate for flexible and reconfigurable phased-array antennas and other radio frequency (RF) and microwave frequency applications.
      PubDate: Wed, 28 Mar 2018 00:00:00 +000
       
  • Fast Estimation Method of Space-Time Two-Dimensional Positioning
           Parameters Based on Hadamard Product

    • Abstract: The estimation speed of positioning parameters determines the effectiveness of the positioning system. The time of arrival (TOA) and direction of arrival (DOA) parameters can be estimated by the space-time two-dimensional multiple signal classification (2D-MUSIC) algorithm for array antenna. However, this algorithm needs much time to complete the two-dimensional pseudo spectral peak search, which makes it difficult to apply in practice. Aiming at solving this problem, a fast estimation method of space-time two-dimensional positioning parameters based on Hadamard product is proposed in orthogonal frequency division multiplexing (OFDM) system, and the Cramer-Rao bound (CRB) is also presented. Firstly, according to the channel frequency domain response vector of each array, the channel frequency domain estimation vector is constructed using the Hadamard product form containing location information. Then, the autocorrelation matrix of the channel response vector for the extended array element in frequency domain and the noise subspace are calculated successively. Finally, by combining the closed-form solution and parameter pairing, the fast joint estimation for time delay and arrival direction is accomplished. The theoretical analysis and simulation results show that the proposed algorithm can significantly reduce the computational complexity and guarantee that the estimation accuracy is not only better than estimating signal parameters via rotational invariance techniques (ESPRIT) algorithm and 2D matrix pencil (MP) algorithm but also close to 2D-MUSIC algorithm. Moreover, the proposed algorithm also has certain adaptability to multipath environment and effectively improves the ability of fast acquisition of location parameters.
      PubDate: Mon, 26 Mar 2018 00:00:00 +000
       
  • Miniaturized Printed Inverted-F Antenna for Internet of Things: A Design
           on PCB with a Meandering Line and Shorting Strip

    • Abstract: This paper focuses on a printed inverted-F antenna (PIFA) with meandering line and meandering shorting strip under 2.4 GHz industrial, scientific, and medical (ISM) band for Internet of things (IoT) applications. Bluetooth Low Energy (BLE) technology is one of potential platforms and technologies for IoT applications under ISM band. Printed circuit board (PCB) antenna commonly used in commercial and medical applications because of its small size, low profile, and low cost compared to low temperature cofired ceramic (LTCC) technology. The proposed structure of PIFA is implemented on PCB to gain all these advantages. Replacing conventional PCB line in PIFA by the meandering line and meandering shorting strip improves the efficiency of the PIFA as well as the bandwidth. As a case study, design and measurement results of the proposed PIFA are presented.
      PubDate: Mon, 26 Mar 2018 00:00:00 +000
       
  • Mixed Far-Field and Near-Field Source Localization Algorithm via Sparse
           Subarrays

    • Abstract: Based on a dual-size shift invariance sparse linear array, this paper presents a novel algorithm for the localization of mixed far-field and near-field sources. First, by constructing a cumulant matrix with only direction-of-arrival (DOA) information, the proposed algorithm decouples the DOA estimation from the range estimation. The cumulant-domain quarter-wavelength invariance yields unambiguous estimates of DOAs, which are then used as coarse references to disambiguate the phase ambiguities in fine estimates induced from the larger spatial invariance. Then, based on the estimated DOAs, another cumulant matrix is derived and decoupled to generate unambiguous and cyclically ambiguous estimates of range parameter. According to the coarse range estimation, the types of sources can be identified and the unambiguous fine range estimates of NF sources are obtained after disambiguation. Compared with some existing algorithms, the proposed algorithm enjoys extended array aperture and higher estimation accuracy. Simulation results are given to validate the performance of the proposed algorithm.
      PubDate: Mon, 26 Mar 2018 00:00:00 +000
       
  • Beam-Doppler Unitary ESPRIT for Multitarget DOA Estimation

    • Abstract: High-resolution direction of arrival (DOA) estimation is a critical issue for mainbeam multitarget tracking in ground-based or airborne early warning radar system. A beam-Doppler unitary ESPRIT (BD-UESPRIT) algorithm is proposed to deal with this problem. Firstly, multiple snapshots without spatial aperture loss are obtained by using the technique of time-smoothing. Then the conjugate centrosymmetric discrete Fourier transform (DFT) matrix is used to transform the extracted data into beam-Doppler domain. Finally, the rotational invariance property of the space-time beam is exploited to estimate DOA of the target. The DOA estimation accuracy is improved greatly because the proposed algorithm takes full advantage of temporal information of the signal. Furthermore, the computational complexity of the presented algorithm is reduced dramatically, because the degree of freedom after beam transformation is very small and most of the operations are implemented in real-number domain. Numerical examples are given to verify the effectiveness of the proposed algorithm.
      PubDate: Mon, 26 Mar 2018 00:00:00 +000
       
  • Theoretical and Experimental Comparison Results of Dual-Channel 3D
           Quasi-Optical Network System between Frequency Selective Surface and Wire
           Grid Polarizer

    • Abstract: A dual-channel 3D quasi-optical network (QON) system is analyzed and compared by theoretical and experimental results. It is divided into dual-channel signals by frequency selective surface (FSS) or wire grid polarizer (WGP) for transmitting the 324 GHz signal on the top layer while diverting the 183 GHz signal to the bottom layer. The system structure based on the beam radius is traced by the complex beam parameter and system transfer matrix for deciding the positions of cascade mirrors. The design principles and test results of FSS with perforated hexagonal array and WGP printed on the dielectric substrate are discussed together. In order to evaluate channel performance, the output planar near-fields of QON system are simulated and tested by the four reflections and three transmission results, respectively, where both scalar and vector conversion efficiencies are used to evaluate the quality of output beams. For the distortion phenomenon and energy loss in planar field, the aperture modes of corrugated horn feeds are analyzed by spherical wave expansion (SWE) to explain the asymmetrical pattern characteristic. The cut section of the far-field pattern is also directly measured in the compact antenna test range (CATR), comparing with the far-field patterns that are indirectly obtained based on the principle of near-to-far-field transformation and ideal aperture field integral of quiet zone (QZ). The differences between the near- and far-field test in QON have been compared, and discussion that the corresponding experimental results verify the WGP has better work performance in the good pattern symmetry, high cross-polarization isolation, low energy loss, and side-lobe level.
      PubDate: Mon, 26 Mar 2018 00:00:00 +000
       
  • Beam Synthesis with Low-Bit Reflective Coding Metamaterial Antenna:
           Theoretical and Experimental Results

    • Abstract: Coding metamaterials are the new technology where the aperture coding provides the hardware foundation for the miniaturization of the devices. As a synthetic 2-D plane, metamaterial antennas are composed of subwavelength resonant particles. It can realize real-time control of electromagnetic wave and build multifunction radar array system. We make a detailed explanation of its array structure, working principle, and hardware system. However, it is usually difficult to synthesize flexible beams because the phase value is very limited in this antenna. Two methods are proposed in this paper to demonstrate the beam synthesis based on repetitive coding and convolution, and the distribution of beam pointings is analysed on the basis of this mechanism. Experiments that measure the radiation pattern of this antenna are carried out to verify the simulated results using only 1-bit coding metasurface in a radar system, whose phase value is controlled by pin diode on the surface.
      PubDate: Mon, 26 Mar 2018 00:00:00 +000
       
  • Multiobjective Optimization Design of Time-Modulated Concentric Circular
           Ring Arrays

    • Abstract: A multiobjective approach based on the third evolution step of generalized differential evolution (GDE3) algorithm is proposed for optimizing the time-modulated array (TMA) in this paper. Different from the single-objective optimization, which optimizes a weighted sum of the peak sidelobe level (PSLL) and the peak sideband level (PSBL) of the array, the multiobjective algorithm treats the PSLL and the PSBL as two distinct objectives that are to be optimized simultaneously. Furthermore, not only one outstanding optimization result can be acquired but also a set of solutions known as Pareto front is obtained by using the GDE3 algorithm, which will guide the design of time-modulated array more effectively. Users can choose one appropriate outcome which has a suitable tradeoff between the PSLL and the PSBL. This approach is illustrated through a time-modulated concentric circular ring array (CCRA). The optimal parameters and the corresponding radiation patterns are presented at last. Experimental results reveal that the multiobjective optimization can be an effective approach for the TMA synthesis problems.
      PubDate: Sun, 25 Mar 2018 00:00:00 +000
       
  • 2D Gain Enhancement Based on Single-Layer SIW Corrugated Technique with
           Slot Array Feeder

    • Abstract: Novel slot-array-based SIW corrugated technique is demonstrated to achieve 2D gain enhancement, namely, sharpening the beamwidths in both E-plane and H-plane. Compared to other metallic corrugated methods to realize 2D gain enhancement, the proposed design, with SIW grooves to reduce the beamwidth in E-plane and slot array to increase the directivity in H-plane, has a lower profile, weight, and design complexity, which can be easily fabricated with the common printed circuit board (PCB) technique. A prototype is designed and fabricated, with measurement presenting a low reflection coefficient less than −10 dB from 26.4 GHz to 28.2 GHz and an enhanced gain up to 18 dB. Overall, our proposed technique will be beneficial for the design of high-gain antenna in 5G wireless terminals.
      PubDate: Sun, 25 Mar 2018 00:00:00 +000
       
  • Parabolic Equation Modeling of Propagation over Terrain Using Digital
           Elevation Model

    • Abstract: The parabolic equation method based on digital elevation model (DEM) is applied on propagation predictions over irregular terrains. Starting from a parabolic approximation to the Helmholtz equation, a wide-angle parabolic equation is deduced under the assumption of forward propagation and the split-step Fourier transform algorithm is used to solve it. The application of DEM is extended to the Cartesian coordinate system and expected to provide a precise representation of a three-dimensional surface with high efficiency. In order to validate the accuracy, a perfectly conducting Gaussian terrain profile is simulated and the results are compared with the shift map. As a consequence, a good agreement is observed. Besides, another example is given to provide a theoretical basis and reference for DEM selection. The simulation results demonstrate that the prediction errors will be obvious only when the resolution of the DEM used is much larger than the range step in the PE method.
      PubDate: Wed, 21 Mar 2018 00:00:00 +000
       
  • Improved Microstrip Antenna with HIS Elements and FSS Superstrate for
           2.4 GHz Band Applications

    • Abstract: This research presents a microstrip antenna integrated with the high-impedance surface (HIS) elements and the modified frequency selective surface (FSS) superstrate for 2.4 GHz band applications. The electromagnetic band gap (EBG) structure was utilized in the fabrication of both the HIS and FSS structures. An FR-4 substrate with 120 mm × 120 mm × 0.8 mm in dimension (W × L × T) and a dielectric constant of 4.3 was used in the antenna design. In the antenna development, the HIS elemental structure was mounted onto the antenna substrate around the radiation patch to suppress the surface wave, and the modified FSS superstrate was suspended 20 mm above the radiating patch to improve the directivity. Simulations were carried out to determine the optimal dimensions of the components and the antenna prototype subsequently fabricated and tested. The simulation and measured results were agreeable. The experimental results revealed that the proposed integrated antenna (i.e., the microstrip antenna with the HIS and FSS structures) outperformed the conventional microstrip antenna with regard to reflection coefficient, the radiation pattern, gain, and radiation efficiency. Specifically, the proposed antenna could achieve the measured antenna gain of 10.14 dBi at 2.45 GHz and the reflection coefficient of less than −10 dB and was operable in the 2.39–2.51 GHz frequency range.
      PubDate: Wed, 21 Mar 2018 00:00:00 +000
       
  • Accurate 3D Mapping Algorithm for Flexible Antennas

    • Abstract: This work addresses the problem of performing an accurate 3D mapping of a flexible antenna surface. Consider a high-gain satellite flexible antenna; even a submillimeter change in the antenna surface may lead to a considerable loss in the antenna gain. Using a robotic subreflector, such changes can be compensated for. Yet, in order to perform such tuning, an accurate 3D mapping of the main antenna is required. This paper presents a general method for performing an accurate 3D mapping of marked surfaces such as satellite dish antennas. Motivated by the novel technology for nanosatellites with flexible high-gain antennas, we propose a new accurate mapping framework which requires a small-sized monocamera and known patterns on the antenna surface. The experimental result shows that the presented mapping method can detect changes up to 0.1-millimeter accuracy, while the camera is located 1 meter away from the dish, allowing an RF antenna optimization for Ka and Ku frequencies. Such optimization process can improve the gain of the flexible antennas and allow an adaptive beam shaping. The presented method is currently being implemented on a nanosatellite which is scheduled to be launched at the end of 2018.
      PubDate: Tue, 20 Mar 2018 07:04:28 +000
       
  • A Ring-Focus Antenna with Splash Plate in Ka-Band

    • Abstract: A design for Ka-band satellite communication antenna in earth station is introduced. This kind of antenna uses splash plate feed based on ring-focus antenna. The theory of the new splash plate feed design is presented and the relative equations are derived. The measured antenna parameters, VSWR, and patterns are highly consistent with the simulated results, which demonstrates the success of the design for such kind of antenna that can be effectively used in Ka-band applications.
      PubDate: Sun, 18 Mar 2018 00:00:00 +000
       
  • Local Degree of Freedom of Clutter for Reduced-Dimension Space-Time
           Adaptive Processing with MIMO Radar

    • Abstract: Degree of freedom (DOF) of clutter in the reduced-dimension (RD) domain, which is called local DOF (LDOF), is of great importance for RD MIMO-STAP (space-time adaptive processing for multiple-input multiple-output radar) algorithms. In this paper, the LDOF equivalence of different RD MIMO-STAP algorithms are firstly proved, and then a generalized LDOF estimation rule under different conditions is developed to estimate the clutter LDOF for MIMO radar effectively. The accuracy of the proposed rule is verified, and how to design RD MIMO-STAP processors under the guidance of the proposed rule is presented through numerical simulations.
      PubDate: Sun, 18 Mar 2018 00:00:00 +000
       
  • Frequency-Reconfigurable Dipole Antenna Using Liquid-Metal Pixels

    • Abstract: A frequency-tunable half-wavelength dipole antenna is realized using an array of electrically actuated liquid-metal pixels. The liquid-metal pixelated dipole antenna demonstrates frequency reconfigurability by switching between resonances at 2.51 GHz, 2.12 GHz, 1.85 GHz, and 1.68 GHz.
      PubDate: Wed, 14 Mar 2018 00:00:00 +000
       
  • A Novel Wideband Circularly Polarized Antenna for RF Energy Harvesting in
           Wireless Sensor Nodes

    • Abstract: A novel wideband circularly polarized antenna array using sequential rotation feeding network is presented in this paper. The proposed antenna array has a relative bandwidth of 38.7% at frequencies from 5.05 GHz to 7.45 GHz with a highest gain of 12 dBi at 6 GHz. A corresponding left-handed metamaterial is designed in order to increase antenna gain without significantly affecting its polarization characteristics. The wideband circularly polarized antenna with 2.4 GHz of bandwidth is a promising solution for wireless communication system such as tracking or wireless energy harvesting from Wi-Fi signal based on IEEE 802.11ac standard or future 5G cellular. A potential application of this antenna as a receiving antenna for RF-DC device to obtain DC power for a wireless sensor node from Wi-Fi signal is shown.
      PubDate: Sun, 11 Mar 2018 00:00:00 +000
       
  • A Compact Coupled-Fed Loop Antenna for Mobile LTE Smartphones

    • Abstract: A coupled-fed loop antenna with Octa-bands operation for long-term evolution (LTE) smartphones is proposed in this paper. The antenna occupies a nonground space of only 6.5 mm × 72 mm, and two wide-band operations can be achieved by exploiting the multimode characteristics of loop antenna and using high-pass matching circuits. In low band, the LTE700/GSM850/900 operation is achieved by the loop mode of 0.5 λ and matching chip capacitor which generates a dual-resonance mode at 0.74 GHz and 0.9 GHz. In high band, the 1 λ mode, the 1.5 λ mode, and the 2 λ mode of the entire loop are combined with the 0.5 λ mode of the left-side coupling loop to cover the DCS1800/PCS1900/UMTS 2100/LTE 2300/2500 operation bands. The measured average realized gains and efficiencies are approximately 1.56 dBi/2.38 dBi and 55.3%/63.6% in the two bands, and a good radiation pattern is achieved as well.
      PubDate: Sun, 11 Mar 2018 00:00:00 +000
       
 
 
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