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Publisher: Hindawi   (Total: 339 journals)

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Showing 1 - 200 of 339 Journals sorted alphabetically
Abstract and Applied Analysis     Open Access   (Followers: 3, SJR: 0.343, CiteScore: 1)
Active and Passive Electronic Components     Open Access   (Followers: 7, SJR: 0.136, CiteScore: 0)
Advances in Acoustics and Vibration     Open Access   (Followers: 36, SJR: 0.147, CiteScore: 0)
Advances in Aerospace Engineering     Open Access   (Followers: 54)
Advances in Agriculture     Open Access   (Followers: 10)
Advances in Artificial Intelligence     Open Access   (Followers: 15)
Advances in Astronomy     Open Access   (Followers: 39, SJR: 0.257, CiteScore: 1)
Advances in Bioinformatics     Open Access   (Followers: 17, SJR: 0.565, CiteScore: 2)
Advances in Biology     Open Access   (Followers: 9)
Advances in Chemistry     Open Access   (Followers: 24)
Advances in Civil Engineering     Open Access   (Followers: 43, SJR: 0.539, CiteScore: 1)
Advances in Computer Engineering     Open Access   (Followers: 4)
Advances in Condensed Matter Physics     Open Access   (Followers: 11, SJR: 0.315, CiteScore: 1)
Advances in Decision Sciences     Open Access   (Followers: 3, SJR: 0.303, CiteScore: 1)
Advances in Electrical Engineering     Open Access   (Followers: 33)
Advances in Electronics     Open Access   (Followers: 76)
Advances in Emergency Medicine     Open Access   (Followers: 12)
Advances in Endocrinology     Open Access   (Followers: 5)
Advances in Environmental Chemistry     Open Access   (Followers: 7)
Advances in Epidemiology     Open Access   (Followers: 8)
Advances in Fuzzy Systems     Open Access   (Followers: 5, SJR: 0.161, CiteScore: 1)
Advances in Geology     Open Access   (Followers: 19)
Advances in Geriatrics     Open Access   (Followers: 5)
Advances in Hematology     Open Access   (Followers: 11, SJR: 0.661, CiteScore: 2)
Advances in Hepatology     Open Access   (Followers: 2)
Advances in High Energy Physics     Open Access   (Followers: 19, SJR: 0.866, CiteScore: 2)
Advances in Human-Computer Interaction     Open Access   (Followers: 21, SJR: 0.186, CiteScore: 1)
Advances in Materials Science and Engineering     Open Access   (Followers: 30, SJR: 0.315, CiteScore: 1)
Advances in Mathematical Physics     Open Access   (Followers: 5, SJR: 0.218, CiteScore: 1)
Advances in Medicine     Open Access   (Followers: 3)
Advances in Meteorology     Open Access   (Followers: 24, SJR: 0.48, CiteScore: 1)
Advances in Multimedia     Open Access   (Followers: 2, SJR: 0.173, CiteScore: 1)
Advances in Nonlinear Optics     Open Access   (Followers: 6)
Advances in Numerical Analysis     Open Access   (Followers: 7)
Advances in Nursing     Open Access   (Followers: 32)
Advances in Operations Research     Open Access   (Followers: 12, SJR: 0.205, CiteScore: 1)
Advances in Optical Technologies     Open Access   (Followers: 4, SJR: 0.214, CiteScore: 1)
Advances in Optics     Open Access   (Followers: 5)
Advances in OptoElectronics     Open Access   (Followers: 6, SJR: 0.141, CiteScore: 0)
Advances in Orthopedics     Open Access   (Followers: 8, SJR: 0.922, CiteScore: 2)
Advances in Pharmacological Sciences     Open Access   (Followers: 8, SJR: 0.591, CiteScore: 2)
Advances in Physical Chemistry     Open Access   (Followers: 10, SJR: 0.179, CiteScore: 1)
Advances in Power Electronics     Open Access   (Followers: 33, SJR: 0.184, CiteScore: 0)
Advances in Preventive Medicine     Open Access   (Followers: 6)
Advances in Public Health     Open Access   (Followers: 24)
Advances in Regenerative Medicine     Open Access   (Followers: 3)
Advances in Software Engineering     Open Access   (Followers: 10)
Advances in Statistics     Open Access   (Followers: 4)
Advances in Toxicology     Open Access   (Followers: 2)
Advances in Tribology     Open Access   (Followers: 14, SJR: 0.265, CiteScore: 1)
Advances in Urology     Open Access   (Followers: 9, SJR: 0.51, CiteScore: 1)
Advances in Virology     Open Access   (Followers: 7, SJR: 0.838, CiteScore: 2)
AIDS Research and Treatment     Open Access   (Followers: 3, SJR: 0.758, CiteScore: 2)
Analytical Cellular Pathology     Open Access   (Followers: 2, SJR: 0.886, CiteScore: 2)
Anatomy Research Intl.     Open Access   (Followers: 2)
Anemia     Open Access   (Followers: 5, SJR: 0.669, CiteScore: 2)
Anesthesiology Research and Practice     Open Access   (Followers: 14, SJR: 0.501, CiteScore: 1)
Applied and Environmental Soil Science     Open Access   (Followers: 17, SJR: 0.451, CiteScore: 1)
Applied Bionics and Biomechanics     Open Access   (Followers: 7, SJR: 0.288, CiteScore: 1)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 14)
Archaea     Open Access   (Followers: 3, SJR: 0.852, CiteScore: 2)
Arthritis     Open Access   (Followers: 6, SJR: 0.454, CiteScore: 1)
Autism Research and Treatment     Open Access   (Followers: 27)
Autoimmune Diseases     Open Access   (Followers: 3, SJR: 0.805, CiteScore: 2)
Behavioural Neurology     Open Access   (Followers: 10, SJR: 0.786, CiteScore: 2)
Biochemistry Research Intl.     Open Access   (Followers: 6, SJR: 0.437, CiteScore: 2)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11, SJR: 0.419, CiteScore: 2)
BioMed Research Intl.     Open Access   (Followers: 4, SJR: 0.935, CiteScore: 3)
Biotechnology Research Intl.     Open Access   (Followers: 1)
Bone Marrow Research     Open Access   (Followers: 2, SJR: 0.531, CiteScore: 1)
Canadian J. of Gastroenterology & Hepatology     Open Access   (Followers: 6, SJR: 0.867, CiteScore: 1)
Canadian J. of Infectious Diseases and Medical Microbiology     Open Access   (Followers: 5, SJR: 0.548, CiteScore: 1)
Canadian Respiratory J.     Open Access   (Followers: 1, SJR: 0.474, CiteScore: 1)
Cardiology Research and Practice     Open Access   (Followers: 8, SJR: 1.237, CiteScore: 4)
Case Reports in Anesthesiology     Open Access   (Followers: 10)
Case Reports in Cardiology     Open Access   (Followers: 4, SJR: 0.219, CiteScore: 0)
Case Reports in Critical Care     Open Access   (Followers: 9)
Case Reports in Dentistry     Open Access   (Followers: 5, SJR: 0.229, CiteScore: 0)
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: 0.209, CiteScore: 1)
Case Reports in Gastrointestinal Medicine     Open Access   (Followers: 3)
Case Reports in Genetics     Open Access   (Followers: 1)
Case Reports in Hematology     Open Access   (Followers: 4)
Case Reports in Hepatology     Open Access   (Followers: 2)
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, SJR: 0.204, CiteScore: 1)
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: 7)
Case Reports in Psychiatry     Open Access   (Followers: 13)
Case Reports in Pulmonology     Open Access   (Followers: 3)
Case Reports in Radiology     Open Access   (Followers: 9)
Case Reports in Rheumatology     Open Access   (Followers: 6)
Case Reports in Surgery     Open Access   (Followers: 11)
Case Reports in Transplantation     Open Access  
Case Reports in Urology     Open Access   (Followers: 9)
Case Reports in Vascular Medicine     Open Access  
Case Reports in Veterinary Medicine     Open Access   (Followers: 5)
Child Development Research     Open Access   (Followers: 18, SJR: 0.144, CiteScore: 0)
Chinese J. of Engineering     Open Access   (Followers: 2, SJR: 0.114, CiteScore: 0)
Chinese J. of Mathematics     Open Access  
Cholesterol     Open Access   (Followers: 1, SJR: 0.424, CiteScore: 1)
Chromatography Research Intl.     Open Access   (Followers: 6)
Complexity     Hybrid Journal   (Followers: 6, SJR: 0.531, CiteScore: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2, SJR: 0.403, CiteScore: 1)
Computational Intelligence and Neuroscience     Open Access   (Followers: 12, SJR: 0.326, CiteScore: 1)
Contrast Media & Molecular Imaging     Open Access   (Followers: 3, SJR: 0.842, CiteScore: 3)
Critical Care Research and Practice     Open Access   (Followers: 12, SJR: 0.499, CiteScore: 1)
Current Gerontology and Geriatrics Research     Open Access   (Followers: 9, SJR: 0.512, CiteScore: 2)
Depression Research and Treatment     Open Access   (Followers: 15, SJR: 0.816, CiteScore: 2)
Dermatology Research and Practice     Open Access   (Followers: 3, SJR: 0.806, CiteScore: 2)
Diagnostic and Therapeutic Endoscopy     Open Access   (Followers: 1, SJR: 0.201, CiteScore: 1)
Discrete Dynamics in Nature and Society     Open Access   (Followers: 5, SJR: 0.279, CiteScore: 1)
Disease Markers     Open Access   (Followers: 1, SJR: 0.9, CiteScore: 2)
Economics Research Intl.     Open Access   (Followers: 1)
Education Research Intl.     Open Access   (Followers: 19)
Emergency Medicine Intl.     Open Access   (Followers: 9, SJR: 0.298, CiteScore: 1)
Enzyme Research     Open Access   (Followers: 4, SJR: 0.653, CiteScore: 3)
Evidence-based Complementary and Alternative Medicine     Open Access   (Followers: 22, SJR: 0.683, CiteScore: 2)
Game Theory     Open Access   (Followers: 1)
Gastroenterology Research and Practice     Open Access   (Followers: 3, SJR: 0.768, CiteScore: 2)
Genetics Research Intl.     Open Access   (Followers: 1, SJR: 0.61, CiteScore: 2)
Geofluids     Open Access   (Followers: 4, SJR: 0.952, CiteScore: 2)
Hepatitis Research and Treatment     Open Access   (Followers: 6, SJR: 0.389, CiteScore: 2)
HPB Surgery     Open Access   (Followers: 6, SJR: 0.824, CiteScore: 2)
Infectious Diseases in Obstetrics and Gynecology     Open Access   (Followers: 5, SJR: 1.27, CiteScore: 2)
Interdisciplinary Perspectives on Infectious Diseases     Open Access   (Followers: 1, SJR: 0.627, CiteScore: 2)
Intl. J. of Aerospace Engineering     Open Access   (Followers: 74, SJR: 0.232, CiteScore: 1)
Intl. J. of Agronomy     Open Access   (Followers: 6, SJR: 0.311, CiteScore: 1)
Intl. J. of Alzheimer's Disease     Open Access   (Followers: 11, SJR: 0.787, CiteScore: 3)
Intl. J. of Analysis     Open Access  
Intl. J. of Analytical Chemistry     Open Access   (Followers: 22, SJR: 0.285, CiteScore: 1)
Intl. J. of Antennas and Propagation     Open Access   (Followers: 11, SJR: 0.233, CiteScore: 1)
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: 0.511, CiteScore: 2)
Intl. J. of Biomedical Imaging     Open Access   (Followers: 3, SJR: 0.501, CiteScore: 2)
Intl. J. of Breast Cancer     Open Access   (Followers: 13, SJR: 1.025, CiteScore: 2)
Intl. J. of Cell Biology     Open Access   (Followers: 4, SJR: 1.887, CiteScore: 4)
Intl. J. of Chemical Engineering     Open Access   (Followers: 8, SJR: 0.327, CiteScore: 1)
Intl. J. of Chronic Diseases     Open Access   (Followers: 1)
Intl. J. of Combinatorics     Open Access   (Followers: 1)
Intl. J. of Computer Games Technology     Open Access   (Followers: 10, SJR: 0.287, CiteScore: 2)
Intl. J. of Corrosion     Open Access   (Followers: 10, SJR: 0.194, CiteScore: 1)
Intl. J. of Dentistry     Open Access   (Followers: 6, SJR: 0.649, CiteScore: 2)
Intl. J. of Differential Equations     Open Access   (Followers: 8, SJR: 0.191, CiteScore: 0)
Intl. J. of Digital Multimedia Broadcasting     Open Access   (Followers: 5, SJR: 0.296, CiteScore: 2)
Intl. J. of Electrochemistry     Open Access   (Followers: 8)
Intl. J. of Endocrinology     Open Access   (Followers: 4, SJR: 1.012, CiteScore: 3)
Intl. J. of Engineering Mathematics     Open Access   (Followers: 5)
Intl. J. of Food Science     Open Access   (Followers: 4, SJR: 0.44, CiteScore: 2)
Intl. J. of Forestry Research     Open Access   (Followers: 3, SJR: 0.373, CiteScore: 1)
Intl. J. of Genomics     Open Access   (Followers: 2, SJR: 0.868, CiteScore: 3)
Intl. J. of Geophysics     Open Access   (Followers: 4, SJR: 0.182, CiteScore: 1)
Intl. J. of Hepatology     Open Access   (Followers: 5, SJR: 0.874, CiteScore: 2)
Intl. J. of Hypertension     Open Access   (Followers: 6, SJR: 0.578, CiteScore: 1)
Intl. J. of Inflammation     Open Access   (SJR: 1.264, CiteScore: 3)
Intl. J. of Inorganic Chemistry     Open Access   (Followers: 3)
Intl. J. of Manufacturing Engineering     Open Access   (Followers: 2)
Intl. J. of Mathematics and Mathematical Sciences     Open Access   (Followers: 3, SJR: 0.177, CiteScore: 0)
Intl. J. of Medicinal Chemistry     Open Access   (Followers: 6, SJR: 0.31, CiteScore: 1)
Intl. J. of Metals     Open Access   (Followers: 4)
Intl. J. of Microbiology     Open Access   (Followers: 4, SJR: 0.662, CiteScore: 2)
Intl. J. of Microwave Science and Technology     Open Access   (Followers: 3, SJR: 0.136, CiteScore: 1)
Intl. J. of Navigation and Observation     Open Access   (Followers: 20, SJR: 0.267, CiteScore: 2)
Intl. J. of Nephrology     Open Access   (Followers: 1, SJR: 0.697, CiteScore: 1)
Intl. J. of Oceanography     Open Access   (Followers: 7)
Intl. J. of Optics     Open Access   (Followers: 7, SJR: 0.231, CiteScore: 1)
Intl. J. of Otolaryngology     Open Access   (Followers: 3)
Intl. J. of Partial Differential Equations     Open Access   (Followers: 2)
Intl. J. of Pediatrics     Open Access   (Followers: 6)
Intl. J. of Peptides     Open Access   (Followers: 4, SJR: 0.46, CiteScore: 1)
Intl. J. of Photoenergy     Open Access   (Followers: 2, SJR: 0.341, CiteScore: 1)
Intl. J. of Plant Genomics     Open Access   (Followers: 4, SJR: 0.583, CiteScore: 1)
Intl. J. of Polymer Science     Open Access   (Followers: 24, SJR: 0.298, CiteScore: 1)
Intl. J. of Population Research     Open Access   (Followers: 3)
Intl. J. of Quality, Statistics, and Reliability     Open Access   (Followers: 16)
Intl. J. of Reconfigurable Computing     Open Access   (SJR: 0.123, CiteScore: 1)
Intl. J. of Reproductive Medicine     Open Access   (Followers: 4)
Intl. J. of Rheumatology     Open Access   (Followers: 4, SJR: 0.645, CiteScore: 2)
Intl. J. of Rotating Machinery     Open Access   (Followers: 2, SJR: 0.193, CiteScore: 1)
Intl. J. of Spectroscopy     Open Access   (Followers: 8)
Intl. J. of Stochastic Analysis     Open Access   (Followers: 3, SJR: 0.279, CiteScore: 1)
Intl. J. of Surgical Oncology     Open Access   (Followers: 1, SJR: 0.573, CiteScore: 2)
Intl. J. of Telemedicine and Applications     Open Access   (Followers: 5, SJR: 0.403, CiteScore: 2)
Intl. J. of Vascular Medicine     Open Access   (SJR: 0.782, CiteScore: 2)
Intl. J. of Zoology     Open Access   (Followers: 2, SJR: 0.209, CiteScore: 1)
Intl. Scholarly Research Notices     Open Access   (Followers: 198)
ISRN Astronomy and Astrophysics     Open Access   (Followers: 7)
J. of Addiction     Open Access   (Followers: 14)
J. of Advanced Transportation     Hybrid Journal   (Followers: 13, SJR: 0.581, CiteScore: 1)
J. of Aerodynamics     Open Access   (Followers: 12)

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Journal Cover
International Journal of Antennas and Propagation
Journal Prestige (SJR): 0.233
Citation Impact (citeScore): 1
Number of Followers: 11  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1687-5869 - ISSN (Online) 1687-5877
Published by Hindawi Homepage  [339 journals]
  • Wideband Dual-Polarized Quasi-Omnidirectional Antenna with High Isolation
           for Mobile Applications in High-Speed Vehicles

    • Abstract: A new wideband dual-polarized (DP) quasi-omnidirectional antenna is proposed. The DP antenna consists of a vertical slot for horizontal polarization (HP) and a folded horizontal slot for vertical polarization (VP). A tapered strip is employed to coupling feed the vertical slot while a straight strip is used to excite the horizontal slot. Due to the coupling feed and the orthogonality between the vertical and horizontal slots, the DP antenna features a wide bandwidth and a very high isolation. The simulated isolation is higher than 70 dB, although the measured isolation is about 50 dB. As experimental results indicate, the DP antenna realizes an impedance bandwidth (BW) of 45% (1.7–2.73 GHz) with quasi-omnidirectional radiation patterns for both HP and VP. The DP quasi-omnidirectional antenna may be packaged into a radome with a shape of a blade for mobile applications in high-speed vehicles.
      PubDate: Mon, 18 Feb 2019 23:05:04 +000
  • Modified Minkowski Fractal Unit Cell for Reflectarrays with Low
           Sensitivity to Mutual Coupling Effects

    • Abstract: A single-layer miniaturized reflectarray element with low sensitivity to mutual coupling effects of surrounding elements is presented in this paper. The configuration is proposed to preserve the effectiveness of the infinite array approach in those applications requiring reflectarrays with very small interelement spacing. The inherent ability of the proposed geometry to be adopted in highly miniaturized cells is demonstrated through an extensive analysis of mutual coupling effects on reflectarray phase design curves. In order to prove the independence of the proposed cell to mutual coupling effect, the phase curve variations due to the presence of different surrounding elements with respect to the case of identical cells are evaluated using the well-known extended local periodicity method. Small and negligible mutual coupling errors are retrieved for the proposed miniaturized unit cell, thus demonstrating lower sensitivity to mutual coupling adverse effects.
      PubDate: Mon, 18 Feb 2019 09:05:22 +000
  • Design of a Compact Ultrawideband U-Shaped Slot Etched on a Circular Patch
           Antenna with Notch Band Characteristics for Ultrawideband Applications

    • Abstract: Interference between ultrawideband (UWB) antennas and other narrowband communication systems has spurred growth in designing UWB antennas with notch characteristics and complicated designs consisting of irregular etched slots and larger physical size. This article presents a simplified notched design method for existing UWB antennas exhibiting four frequency-band-rejecting characteristics. The investigation has been conducted by introducing four semicircular U-shaped slot structures based on a theoretical formulation. The formulation is validated with the equivalent LC lumped parameters responsible for yielding the notched frequency. A novel feature of our approach is that the frequency notch can be adjusted to the desired values by changing the radial length based on the value calculated using a derived formula for each semietched U-slot, which is very simple in structure and design. Additionally, by introducing the rectangular notch at the ground plane, the upper passband spectrum is suppressed while maintaining the wide impedance bandwidth of the antenna applicable for next-generation wireless communications, 5G. The measured result shows that the antenna has a wide impedance bandwidth of 149% from 2.9 to 20 GHz, apart from the four-notched frequencies at 3.49, 3.92, 4.57, and 5.23 GHz for a voltage standing wave ratio (VSWR) of
      PubDate: Mon, 18 Feb 2019 09:05:20 +000
  • A Novel Nonlinear LPDA Design for HF Direction Finding

    • Abstract: A novel design of log-periodic dipole array (LPDA) for high-frequency direction finding (DF) is presented. The traditional Carrel method employs fixed values of scale factor and spacing factors in LPDA designs. Here, we propose a design method which uses the continuous change of both the scale factor and the spacing factor so that the length of the dipoles and the space between dipoles vary nonlinearly. One advantage of our design is that the effective distance between the phase center position and the feed point of LPDA can be increased. So the effective radius of the circularly disposed antenna array (CDAA) composed of LPDA is extended, which is important for improving the accuracy of the DF system. Both the simulation and measurement results show that the proposed LPDA achieves larger effective distance and higher gain compared to that using the traditional Carrel method. The proposed LPDA also shows characteristics of wideband impedance matching. The antenna has been successfully applied to practical HF direction finding system.
      PubDate: Sun, 17 Feb 2019 07:05:09 +000
  • Modal Proportion Analysis in Antenna Characteristic Mode Theory

    • Abstract: The characteristic mode theory (CMT) can provide physically intuitive guidance for the analysis and design of antenna structures. In CMT applications, the antenna current distribution is decomposed into the superposition of multiple characteristic modes, and the proportion of each current mode is characterized by the modal weighting coefficient (MWC). However, different characteristic currents themselves have different radiation efficiencies reflected by the eigenvalues. Therefore, from the perspective of the contribution to the radiation field, the modal proportion should be more accurately determined by the combination of the modal weighting coefficient and the mode current itself. Since the discrete mode currents calculated using the electromagnetic numerical method are distributed on the whole conductor surface, we can actually use the radiation field to quantify the modal proportion or estimate it using the far field in the maximum radiation direction. The numerical examples provided in the paper demonstrate that this modal proportion can effectively evaluate antenna performance.
      PubDate: Wed, 13 Feb 2019 10:05:10 +000
  • Inscribed Fibonacci Circle Fractal in a Circular Radiator for
           Ultra-Wideband Antenna Operation and Size Reduction

    • Abstract: In this article, a Fibonacci circle fractal is inscribed into a circular radiator in order to provide ultra-wideband behavior as well as a 50% size reduction compared to a conventional circular monopole. The third iteration of the Fibonacci series allows the antenna to obtain a steady S11 parameter over the operation bandwidth, going from 2.7 GHz to 14 GHz, an average gain around 1 dB, with a quasi-omnidirectional radiation pattern and a group delay no bigger than 1 ns, suitable for short-pulsed communications.
      PubDate: Wed, 13 Feb 2019 09:05:21 +000
  • Experimental Evaluation of MIMO-OFDM System with Rateless Space-Time Block

    • Abstract: Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency-division multiplexing (MIMO-OFDM) is an attractive technique for next-generation wireless systems. However, the performance of wireless links is severely degraded due to various channel impairments which cause a decoding failure and lead to packet loss at the receiver. One technique to cope with this problem is the rateless space-time block code (RSTBC). This paper presents experimental results on the performance of a MIMO-OFDM system with RSTBC as measured in a testbed implemented with field-programmable gate array (FPGA). The average bit error rate (BER) performance of the proposed scheme is evaluated experimentally, and the results agree closely with simulation and analytical upper bound. It has been shown that RSTBC can be implemented in real-world scenarios and guarantee the reliability of loss-prone wireless channels.
      PubDate: Wed, 13 Feb 2019 07:05:09 +000
  • Phase-Only Antenna Array Reconfigurability with Gaussian-Shaped Nulls for
           5G Applications

    • Abstract: This paper presents a fast iterative method for the synthesis of linear and planar antenna arrays of arbitrary geometry that provides pattern reconfigurability for 5G applications. The method enables to generate wide null regions shaped according to a Gaussian distribution, which complies with recent measurements on millimeter-wave (mmWave) angular dispersion. A phase-only control approach is adopted by moving from the pattern provided by a uniformly excited array and iteratively modifying the sole phases of the excitations. This allows the simplification of the array feeding network, hence reducing the cost of realization of 5G base stations and mobile terminals. The proposed algorithm, which is based on the method of successive projections, relies on closed-form expressions for both the projectors and the null positions, thus allowing a fast computation of the excitation phases at each iteration. The effectiveness of the proposed solution is checked through numerical examples compliant with 5G mmWave scenarios and involving linear and concentric ring arrays.
      PubDate: Thu, 07 Feb 2019 10:05:08 +000
  • Wide CPW-Fed Multiband Wearable Monopole Antenna with Extended Grounds for
           GSM/WLAN/WiMAX Applications

    • Abstract: A novel wide coplanar waveguide- (CPW-) fed multiband wearable monopole antenna is presented. The multiband operation is achieved by generating slanted monopoles of different lengths from an isosceles triangular patch. The different operating frequencies of the proposed antenna are associated with the lengths of the slanted monopoles, which are determined under quarter wavelength resonance condition. The CPW line is used as a multiband impedance-matching structure. The two grounds are slightly extended for better impedance matching. The proposed antenna is designed to cover the 1800 MHz GSM, 2.4 GHz/5.2 GHz WLAN, and 3.5 GHz WiMAX bands. The measured peak gains and impedance bandwidths are about 4.18/3.83/2.6/2.94 dBi and 410/260/170/520 MHz for the 1550-1960 MHz/2.3-2.56 GHz/3.4-3.57 GHz/5.0-5.52 GHz bands, respectively. The calculated averaged specific absorption rate (SAR) values at all the resonant frequencies are well below the standard limit of 2 W/kg, which ensures its feasibility for wearable applications. The antenna performance under different bending configurations is investigated and the results are presented. The reflection coefficient characteristics of the proposed antenna is also measured for different on-arm conditions and the results are compared. A good agreement between experimental and simulation results validates the proposed design approach.
      PubDate: Mon, 04 Feb 2019 10:05:09 +000
  • Heuristic UTD Solution for Antennas Near a Complex Platform

    • Abstract: This paper is aimed at developing an approximate and relatively simple but closed-form uniform geometrical theory of diffraction (UTD) solution for describing the radiated and scattered fields by an antenna near a complex platform consisting of a three-dimensional (3-D) thin material-coated metallic surface, including edges and corners. Unlike the previous works that consider primarily plane wave scattering, the developed solution can also treat radiation/scattering problems of antennas near finite material-coated metallic surfaces which are composed of edges and corners. The developed solution, which is formulated by using a heuristic approach, recovers the proper local plane wave Fresnel reflection coefficient. In addition, the developed UTD-diffracted fields will satisfy the radiation condition, boundary conditions on the conductor. The accuracy of the developed solution is verified by comparing with simulation results from a computer software. It is found that the results from our developed solution agree well with those of references. However, some small discrepancies occur but it is good enough for engineering applications. The proposed solution can be very useful for antenna engineers to design multiple antennas with an electrically large complex material-coated platform.
      PubDate: Tue, 29 Jan 2019 07:05:33 +000
  • Influence Analysis of Transmission Lines on a Stable Non-Foster-Loaded
           Electrically Small Dipole

    • Abstract: Non-Foster-loaded antennas have the advantages of compact size and large bandwidth. Meanwhile, they suffer from two issues: internal instability and simulation inaccuracy resulting from distribution parameters. The most commonly used stability analysis method for microwave circuits, Rollett’s criteria, is not suitable for negative impedance circuits. This paper has explained the reason and proposed an effective method for stability analysis. Transmission lines between lumped components are found to be a main reason of inaccurate simulations, which is analyzed in this paper, and it is concluded that their influence also exists at hundreds of megahertz. In order to solve this problem and improve simulation accuracy, circuit and electromagnetic cosimulation is conducted. Finally, a 320 mm dipole loading with a negative capacitor is fabricated to verify the analysis. Simulated and measured results indicate that the proposed stability analysis is effective and the simulation accuracy is significantly improved. The matched dipole achieves less than −10 dB reflection coefficient from 30 MHz to 580 MHz. Furthermore, a 14 dB gain improvement is obtained in electrically small condition.
      PubDate: Mon, 28 Jan 2019 13:30:10 +000
  • Design of a PIN Diode-Based Reconfigurable Metasurface Antenna for Beam
           Switching Applications

    • Abstract: In this paper, we propose a reconfigurable metasurface antenna for beam switching applications. The reconfigurable metasurface is formed by uniformly distributed double-split square rings loaded with positive-intrinsic-negative (PIN) diodes for dual operations of a wave reflector and a wave director. Specifically, when the PIN diodes are forward biased, an epsilon-negative (ENG) metasurface is realized which reflects all incident waves with appropriate polarization; when the diodes are reverse biased, at the same operating frequency, a mu-near-zero (MNZ) metasurface is acquired which directs wave propagation. For excitation, a dipole radiator loaded with the same type of PIN diode is designed. Simulation and measurement results show good agreement and verify the beam switching functionality of the proposed metasurface antenna.
      PubDate: Mon, 28 Jan 2019 11:05:18 +000
  • Electromagnetic Analysis and Experimental Validation of the LOFAR
           Radiation Patterns

    • Abstract: Low-frequency (
      PubDate: Sun, 27 Jan 2019 13:30:11 +000
  • Bistatic ISAR Sparse Imaging Method for High-Speed Moving Target Based on
           Dechirping Processing

    • Abstract: Bistatic inverse synthetic aperture radar (ISAR) can increase the probability of tracking the high-speed target and provide more angle information than monostatic ISAR. However, bistatic ISAR suffers from a serious defocusing problem, resulting from the high-speed motion. Furthermore, the inherent geometry distortion and calibration problems make bistatic ISAR (B-ISAR) imaging more complex. In response to these problems, we propose a bistatic ISAR imaging method for high-speed moving target with geometric distortion correction and calibration based on dechirping processing. At first, based on the motion decomposition idea, the B-ISAR echo model of the high-speed moving target is established. Then, by analyzing the imaging mechanism of the Range-Doppler algorithm (RDA), we eliminate the phase items influencing the imaging quality with speed compensation and Doppler compensation. After that, the analytic formula of the geometric distortion factor and calibration factor are deduced, which helps transform the geometric correction and calibration problem into a parameter estimation problem. Finally, with the sparsity of the scattering points, the required parameters are solved using the expectation maximization (EM) algorithm based on the maximum a posteriori probability criterion. With the estimated parameters, a clear B-ISAR image of a high-speed moving target with geometric correction and calibration is obtained. The simulations show that the proposed method has a better resolution and simultaneously attains geometric correction and calibration of the image.
      PubDate: Sun, 27 Jan 2019 09:05:18 +000
  • Implicit Pilots for an Efficient Channel Estimation in Simplified Massive
           MIMO Schemes with Precoding

    • Abstract: This paper proposes a new channel estimation scheme based on implicit pilots, optimized for a simplified massive multiple input, multiple output (MIMO), implemented with precoding, combined with Single-Carrier with Frequency-Domain Equalization (SC-FDE) modulations. We propose an iterative receiver that considers an iterative detection with interference cancellation and channel estimation. The channel estimates are usually obtained with the help of pilot symbols and/or training sequences multiplexed with data symbols. Since the required overheads in massive MIMO schemes can be too high, leading to spectral degradation, the use of superimposed pilots (i.e., pilots added to data) is an efficient alternative. Three different types of preprocessing algorithms are considered in this paper: Zero-Forcing Transmitter (ZFT), Maximum Ratio Transmitter (MRT), and Equal Gain Transmitter (EGT). The main advantage of MRT and EGT is that they do not require matrix inversions. Nevertheless, some level of interference is generated in the decoding process. Such interference is mitigated by employing an optimized iterative receiver. By employing the proposed implicit pilots, the performance of MRT and EGT is very close to the Matched Filter Bound just after a few iterations, even when the number of transmit or receiver antennas is not much higher than the number of data streams.
      PubDate: Sun, 27 Jan 2019 09:05:17 +000
  • Large-Scale Channel Modeling and Measurements for 10 GHz in Indoor

    • Abstract: With the advent of 5G mobile communication and researches into the propagation of large-scale channel modeling for frequencies above 6 GHz, measurement investigation was performed at 10 GHz with horn-type directional antennas in a corridor and a computer room within the Electrical and Computer Engineering Laboratories’ first floor, at Federal University of Pará (UFPA), Brazil. This paper presents data obtained through experimental work, channel modeling with co-polarization V-V and H-H and cross-polarization V-H in line-of-sight (LOS) or non-line-of-sight (NLOS) conditions. The large-scale close-in reference is sustained by a comprehensive analysis, considering propagation mechanisms such as reflection and diffraction. Results demonstrate that the established model had inferior standard deviation in relation to measured data, proving itself more significant to propagation in indoor environments.
      PubDate: Wed, 23 Jan 2019 13:05:11 +000
  • Combination of MLFMA and ACA to Accelerate Computation of Scattering from
           Underground Targets

    • Abstract: Electromagnetic nondestructive evaluation of underground targets is of great significance for the safety of urban construction. Based on the accurate and efficient simulation of scattering, we can detect the underground targets successfully. As one of the most popular numerical methods in electromagnetics, surface integral equations solved by method of moments (MoM) are used to simulate the scattering from underground targets in this paper. The integral equation is discretized by RWG basis and Galerkin testing. Multilevel fast multipole algorithm (MLFMA) is used to decrease the computation complexity and memory cost. However, the octree used in MLFMA is not applied for rough surfaces and targets together; both the surface and target need to construct octree separately. Since the combination of MLFMA and ACA can build a more efficient method to compute scattering from underground targets, adaptive cross approximation (ACA) is used to compress the impedance matrix instead of MLFMA for the coupling action between the rough surface and target. That is to say that, when calculating the scattering of two targets, target self-interaction is suitable for MLFMA calculation and the coupling between targets is approximated by ACA. Numerical results demonstrate the accuracy and efficiency of our proposed method.
      PubDate: Wed, 23 Jan 2019 07:05:37 +000
  • Wide-Band High-Gain DGS Antenna System for Indoor Robot Positioning

    • Abstract: Based on multisource wireless signal fusion technology, the autonomous positioning systems of robots have been widely employed. How to design a compact compostable antenna array for indoor robot positioning is still a problem. In this study, we proposed a compact ultrathin antenna unit that effectively reduces the mutual coupling between any adjacent units, while covering most of the existing communication bands, including 2G/3G/4G/Wi-Fi, which will greatly reduce the size of the positioning antenna array. The proposed antenna system has been employed for positioning purpose with high-gain, wide-frequency band and limited size. It necessarily improves the accuracy of positioning signal from various unknown sources and finally accomplishes its autonomous positioning function.
      PubDate: Sun, 20 Jan 2019 12:05:13 +000
  • A Study of a Wide-Angle Scanning Phased Array Based on a High-Impedance
           Surface Ground Plane

    • Abstract: This paper presents a two-dimensional infinite dipole array system with a mushroom-like high-impedance surface (HIS) ground plane with wide-angle scanning capability in the E-plane. The unit cell of the proposed antenna array consists of a dipole antenna and a four-by-four HIS ground. The simulation results show that the proposed antenna array can achieve a wide scanning angle of up to 65° in the E-plane with an excellent impedance match and a small S11. Floquet mode analysis is utilized to analyze the active impedance and the reflection coefficient. Good agreement is obtained between the theoretical results and the simulations. Using numerical and theoretical analyses, we reveal the mechanism of such excellent wide scanning properties. For the range of small scanning angles, these excellent properties result mainly from the special reflection phase of the HIS ground, which can cause the mutual coupling between the elements of the real array to be compensated by the mutual coupling effect between the real array and the mirror array. For the range of large scanning angles, since the surface wave (SW) mode could be resonantly excited by a high-order Floquet mode TM−1,0 from the array and since the SW mode could be converted into a leaky wave (LW) mode by the scattering of the array, the radiation field from the LW mode is nearly in phase with the direct radiating field from the array. Therefore, with help from the special reflection phase of the HIS and the designed LW mode of the HIS ground, the antenna array with an HIS ground can achieve a wide-angle scanning performance.
      PubDate: Sun, 20 Jan 2019 08:05:24 +000
  • Application of Compressive Sensing in Solving Monostatic Scattering

    • Abstract: In this paper, a new CS-FMM method that conjugates compressive sensing (CS) with the fast multipole method (FMM) is proposed and validated to efficiently solve monostatic scattering from an arbitrary conducting target. The far zone scattered fields are viewed as the signal of interest. CS is introduced to reduce the number of computations. A new set of incident sources has been generated according to CS. By solving the matrix equations under the new set of incident sources and calculating the related far zone scattered fields, the measurements of the aforementioned signal can be derived. Then, the CS inversion is employed to reconstruct the desired monostatic far zone scattered fields by finding the smallest possible norm solution. Monostatic radar cross section (RCS) from several conducting targets is studied by CS-FMM and by the traditional FMM. And the results are compared with each other to illustrate the accuracy and efficiency of the proposed method.
      PubDate: Thu, 17 Jan 2019 14:05:05 +000
  • Theoretical and Experimental Study on Echo Fluctuation Suppression of a
           Cirrus Cloud by Millimeter Wave MIMO Radar

    • Abstract: The scattering properties of nonspherical particles can be approximately computed by equivalent spherical theory. The scattering properties of ice particles were approximately computed by Rayleigh approximation because the sizes of the ice particles are smaller than the wavelength of millimeter wave radar. Based on the above assumption, the echo fluctuation of moving particles was analyzed by computing the total backscattering field of a cirrus cloud using the classical vector potential technique. The simulation results showed that echo fluctuation influences the accuracy of retrieving the physical parameters of a cloud. To suppress the echo fluctuation of moving ice particles, a video integrator of a millimeter wave cloud radar would be used. However, video integrators lose the rapidly changing information of ice particles and reduce radar range resolution; thus, we propose the pace-diversity technique of MIMO radar to reduce the echo fluctuation, which could be validated by theoretical computation and experimental measurements.
      PubDate: Sun, 13 Jan 2019 09:05:26 +000
  • Parallel Integral Equation-Based Nonoverlapping DDM for Solving
           Challenging Electromagnetic Scattering Problems of Two Thousand

    • Abstract: In this paper, a parallel nonoverlapping and nonconformal domain decomposition method (DDM) is proposed for fast and accurate analysis of electrically large objects in the condition of limited resources. The formulation of nonoverlapping DDM for PEC bodies is derived from combined-field integral equation (CFIE), and an explicit boundary condition is applied to ensure the continuity of electric currents across the boundary. A parallel multilevel fast multipole algorithm (MLFMA) is extended to accelerate matrix-vector multiplications of subdomains as well as the coupling between them, and the coupling between different subdomains is computed in the manner of near field to avoid the storage of the mutual impedance. An improved adaptive direction partitioning scheme is applied to the oct-tree of MLFMA to achieve high parallel efficiency. Numerical examples demonstrate that the proposed method is able to simulate realistic problems with a maximum dimension greater than 2000 wavelengths.
      PubDate: Sun, 06 Jan 2019 14:05:03 +000
  • UWB Metamaterial-Loaded Antenna for C-Band Applications

    • Abstract: A novel metamaterial-inspired patch antenna is proposed, wherein a 2-segment SRR Labyrinth metamaterial is embedded inside the antenna substrate. It is observed that upon incorporation, the bandwidth widens to around 600% and VSWR improves by approx. 1.5% and the antenna is miniaturized by 400%. The Nicolson-Ross-Weir (NRW) method has been used to retrieve the material parameters from transmission and reflection coefficients.
      PubDate: Sun, 06 Jan 2019 13:05:10 +000
  • Investigation on SIW Slot Antenna Array with Beam Scanning Ability

    • Abstract: A sparse substrate integrated waveguide (SIW) slot antenna array and its application on phase scanning are studied in this paper. The genetic algorithm is used to optimize the best arrangement for 8-element and 7-element sparse arrays over an aperture of . Antenna arrays with feeding networks, for steering the main beam pointing to 0° and −15°, are demonstrated with the SIW technology. The comparison between the sparse array and the conventional uniformly spaced array with the same aperture are presented, which suggest that the same beam width can be obtained with the gain decreased by 0.5 or 1 dBi and the number of element reduced by 2 or 3, respectively. The sparse antenna array with beam scanning ability presented in this paper shows that, while the beam scanning in the range of ±15°, the gain fluctuation is less than 0.3 dBi and the side lobe level is lower than −10 dB.
      PubDate: Sun, 06 Jan 2019 08:05:30 +000
  • Proficiency of Leaky Coaxial Cable-Based MIMO System Using Radiated Field

    • Abstract: This paper presents channel propagation characteristics of different multiple-input multiple-output (MIMO) systems using ray tracing approach in a confined area at 1.8 GHz according to the LTE-M standards. Leaky coaxial cables were exploited at different transmitted locations to visualize the fluctuated radiated field under different polarization combinations. In order to encounter this vision, the reflected and line-of-sight paths are under consideration for both vertically and horizontally polarized waves emitting from the leaky coaxial cables (LCXs). Emphasis is given to understand the effect of LCX configuration on the channel correlation coefficient and capacity (C) in the confined area. The exploration of experimental results reveals that the MIMO channel using LCXs has significant performance, specifically in the case of horizontal polarization. Furthermore, it is inferred that for the longer distance between transmitter and receiver, the correlation coefficients have higher magnitude.
      PubDate: Mon, 31 Dec 2018 00:00:00 +000
  • Matrix Generation by First-Order Taylor Expansion in a Localized Manner

    • Abstract: The method of moments is widely used, but its matrix generation is time-consuming. In the present paper, a localized multifrequency matrix-filling method is proposed. The method is based on the retarded first-order Taylor expansion of Green’s functions on each field point, which can reduce the number of callback Green’s functions and hence can solve double-surface integrals quickly. It is also based on the extraction of the common factors of different frequencies, and hence can sweep the frequency points quickly. Numerical examples are provided to validate the efficiencies of the proposed method.
      PubDate: Thu, 27 Dec 2018 07:06:04 +000
  • Compact and Multiband MIMO Dielectric Resonator Antenna for Automotive LTE

    • Abstract: A compact and multiband dielectric resonator antenna (DRA) designed for LTE automotive solutions is presented in this paper. The proposed MIMO system is located on the vehicle rooftop within a limited space of 120 mm × 70 mm × 65 mm. To cover all the LTE standard frequency bands used around the world, the antenna is matched around 790 MHz–860 MHz, 1700 MHz–2200 MHz, and 2500 MHz–2700 MHz frequency bands with a lower than −6 dB while presenting a minimum total efficiency of 50% with a maximum realized gain better than 1 dB on all these frequency bands. The DRA is then mounted and measured on a real vehicle rooftop in order to see its performances in real operation conditions. Finally, to improve both the quality and reliability of the wireless link, two DRAs are placed within a small area to reconfigure their radiation patterns on each frequency band. Measured performances, which are in good agreement with the simulated results, are used to validate if the antenna design is suitable for LTE MIMO systems to be integrated on an automotive. The MIMO system is evaluated using the envelope correlation coefficient (ECC), and the obtained value for the proposed antenna is lower than 0.25.
      PubDate: Thu, 27 Dec 2018 00:00:00 +000
  • Detection of Subsurface Target Based on FDA-MIMO Radar

    • Abstract: As a new type of radar, the FDA-MIMO radar has a good improvement on side lobe suppression and target detection performance compared with the conventional MIMO radar. However, the existing researches on FDA-MIMO radar are almost based on far-field. In this paper, FDA-MIMO radar is applied to the detection of subsurface targets. Aimed at near-subsurface targets, we formulated the signal model of FDA-MIMO radar and combined it with the algorithm of grid of beam (GOB) to detect. Compared with conventional MIMO radar detection, we verified the effectiveness of the proposed method through theoretical simulation.
      PubDate: Sun, 23 Dec 2018 01:45:28 +000
  • Low-Profile Ultra-Broadband Log-Period Monopole End-Fire Antenna

    • Abstract: This paper proposes an ultra-broadband (2–13 GHz) and low-profile log-period monopole end-fire antenna for the flush-mounted applications. 24 monopoles with a log-period rule are used to cover the whole operating frequency band, and those monopoles are printed on both sides of a low-loss dielectric layer vertically placed over a slot feeding line with wideband microstrip-to-slotline transition. The low profile is realized by bending the parts of the long monopoles so that the overall antenna size is obtained as 40 mm × 100 mm × 13.6 mm. The proposed antenna is fabricated, and the measured results agree with the simulated results very well. The measured results indicate that the proposed antenna can work at the whole 2–13 GHz band with very good end-fire radiation patterns and stable gain performances.
      PubDate: Sun, 23 Dec 2018 00:00:00 +000
  • Radar Selection Method Based on an Improved Information Filter in the LPI
           Radar Network

    • Abstract: In order to save the radar resources and obtain the better low probability intercept ability in the network, a novel radar selection method for target tracking based on improved interacting multiple model information filtering (IMM-IF) is presented. Firstly, the relationship model between radar resource and tracking accuracy is built, and the IMM-IF method is presented. Then, the information gain of every radar is predicted according to the IMM-IF, and the radars with larger information gain are selected to track target. Finally, the weight parameters for the tracking fusion are designed after the error covariance prediction of every working radar, in order to improve the IMM-IF. Simulation results show that the proposed algorithm not only saves much more radar resources than other methods but also has excellent tracking accuracy.
      PubDate: Mon, 17 Dec 2018 00:00:00 +000
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