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[Keyword] beam width(3hit)

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  • A Beam Search Method with Adaptive Beam Width Control Based on Area Size for Initial Access

    Takuto ARAI  Daisei UCHIDA  Tatsuhiko IWAKUNI  Shuki WAI  Naoki KITA  

     
    PAPER-Wireless Communication Technologies

      Pubricized:
    2022/10/03
      Vol:
    E106-B No:4
      Page(s):
    359-366

    High gain antennas with narrow-beamforming are required to compensate for the high propagation loss expected in high frequency bands such as the millimeter wave and sub-terahertz wave bands, which are promising for achieving extremely high speeds and capacity. However using narrow-beamforming for initial access (IA) beam search in all directions incurs an excessive overhead. Using wide-beamforming can reduce the overhead for IA but it also shrinks the coverage area due to the lower beamforming gain. Here, it is assumed that there are some situations in which the required coverage distance differs depending on the direction from the antenna. For example, the distance to an floor for a ceiling-mounted antenna varies depending on the direction, and the distance to the obstruction becomes the required coverage distance for an antenna installation design that assumes line-of-sight. In this paper, we propose a novel IA beam search scheme with adaptive beam width control based on the distance to shield obstacles in each direction. Simulations and experiments show that the proposed method reduces the overhead by 20%-50% without shrinking the coverage area in shield environments compared to exhaustive beam search with narrow-beamforming.

  • Miniaturization of Parallel-Plate Lens Antenna for Evaluation of Wave Absorber Placed on Ceiling of ETC Gate Open Access

    Takenori YASUZUMI  Nayuta KAMIYA  Ryosuke SUGA  Osamu HASHIMOTO  Yukinori MATSUSHITA  Yasuyuki MATSUDA  

     
    PAPER-Electromagnetic Compatibility(EMC)

      Vol:
    E95-B No:10
      Page(s):
    3225-3231

    This paper presents a compact metal plate lens antenna for evaluating a wave absorber placed on ceiling of the ETC gate. The focal distance of the lens was derived to be 129 cm by the geometrical optics procedure. By arranging the lens in front of a horn antenna, the gain and beamwidth characteristics were improved from 18 dBi to 26 dBi and from 22 degrees to 7 degrees, respectively. Then the antenna characteristics were evaluated when the distance between the antenna and the lens was changed in order to miniaturize the lens antenna. As the result, the changes in beamwidth were held to within 1 dB when the lens came close to the horn antenna. Scattering, phase and electric field intensity of electromagnetic wave were evaluated to clarify the foundation of the given characteristics. It was found that the field intensity for the miniaturized lens antenna is stronger than that for GO designed one though the phase uniformity is worse. The distance between the horn antenna and lens can be reduced to 80 cm. The absorption characteristics for the arranged absorbers which have different absorptions were measured, and it was shown that the proposed method was suitable for specifying the deteriorated absorber in the ETC system.

  • Analytical Model of Nano-Electromechanical (NEM) Nonvolatile Memory Cells

    Boram HAN  Woo Young CHOI  

     
    BRIEF PAPER

      Vol:
    E95-C No:5
      Page(s):
    914-916

    The fringe field effects of nano-electromechanical (NEM) nonvolatile memory cells have been investigated analytically for the accurate evaluation of NEM memory cells. As the beam width is scaled down, fringe field effect becomes more severe. It has been observed that pull-in, release and hysteresis voltage decrease more than our prediction. Also, the fringe field on cell characteristics has been discussed.