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Thin wave absorbers composed of a periodic structure of metal patches have been investigated in order to reduce the radar cross section (RCS). To achieve stable operation for absorbing frequency at oblique incident angles, a high value of permittivity of the substrate or a very thin substrate are required. This paper presents the RCS reduction characteristics of a metasurface absorber with 0.1-mm...
Gain characteristics improvement of a broadband circularly polarized patch antenna using artificial ground structure is studied. The antenna has a simulated S11 bandwidth of 48.6% and axial ratio bandwidth of less than 3dB of 21.2%. However, gain characteristics of boresight direction decreases in the frequency range of 5.5GHz. In this paper, by modifying shapes of the ground plane, we attempted to...
A novel base station antenna element is proposed. It consists of a surface of parallel strips to rotate the polarization direction and a segment of a rectangular waveguide. The surface is designed on a single-sided substrate, which has the same area as the aperture of the waveguide. In assembling, the non-copper side of the substrate is placed in direct contact with the aperture of the waveguide antenna...
A broadband circularly polarized (CP) reflectarray antenna is proposed. By removal of the four corners of the finite square reflectarray, radiation from surface wave on the array is reduced at the corners. As a result, the 3-dB axial ratio (AR) bandwidth of 27% can be obtained at the center frequency. Furthermore, a design way to control the surface wave by keeping the ground plane square is presented...
The authors have proposed “Active Propagation Control” (APC) as a method to improve receiving transmission performance of a wireless communication channel. By APC, we can obtain better transmission performance by changing propagation characteristics actively in some ways, such as moving, rotating or transforming objects in the surrounding environment. In this paper, we evaluate the variation performance...
Recently, wireless smart meter systems for the life infrastructure such as electricity, gas and water attract much attention. Since radio propagation environments for the smart meter communication in apartment buildings are very complicated, it is difficult to analyze the propagation loss with ray tracing method. This paper proposed a hybrid simulation technique which combines ray tracing and FDTD...
Indoor hotspot has been reorganized as an important part of 5G deployments. To satisfied the new requirements on 5G deployment and facilitate the evaluation of 5G candidate technologies, LOS (line of sight) probability model has been studied in this paper. Compared with the existing models, the new model introduced in this paper fits the propagation in indoor hotspot newly defined for 5G best of the...
In this paper, an empirical propagation model for indoor corridor at 5 GHz based on ray tracing dataset has been proposed. The model can predict the line-of-sight (LOS) and non-line-of-sight (NLOS) path loss characteristics for indoor corridor with T-junction using distances from the junction to the transmitter and receiver, while taking into account the width of the corridor.
This paper presents a method to emulate three-dimension (3D) channel spatial characteristics which is based on genetic algorithm in a MIMO OTA setup. The proposed method applies genetic algorithm to 3D channel reconstruction, which controls the search process to obtain the global optimal solution adaptively. Simulation results show that genetic method gives higher reconstruction accuracy than convex...
For the introduction of CBTC systems to subways, there is a demand to understand the radio propagation characteristics inside tunnels in order to properly design base station intervals. Propagation loss from measurements and ray launching simulations at 2.5 GHz were compared. Simulations were done for curved and sloped tunnels with rectangular and 8-sided cross sections, and straight tunnel with rectangular...
In order to design wireless communication systems for CBTC use in subways, radio propagation characteristics inside tunnels are important. This paper describes 2.5 GHz and 5.7 GHz propagation loss measurements using dipole and patch antennas in a 1200 m section of a newly constructed tunnel which included some slopes and curves. Line-of-sight between transmitter and receiver does not exist after 180...
Broadband wireless communication systems have been studied in both fields of the fixed point communication and the mobile communication. Authors are studying on the application of millimeter-wave to the ground-to-train communication system for high speed train. In this paper, we show the test results of 40 GHz band millimeter-wave propagation characteristics in the railway environment with a focus...
GBAS is the next generation navigation system for aircraft landing using GPS, and is being developed. VDB of GBAS ground subsystem is utilized to send correction information for positioning and integrity monitoring of GPS. VDB coverage is required not only in the air but also above runways to support an auto-land and a roll-out. This paper clarified the effect of buildings on VHF propagation in the...
To better design the coverage areas of wireless base stations, this paper reports the long-term fading, shadow fading, and fast fading characteristics of path loss at 4.7 and 26.4 GHz in a crowded area with pedestrians. We clarified that these fading characteristics of measured path loss broadly matches the Nakagami-Rice distribution. As the results of the analysis with two frequencies, we find that...
In order to overcome the increasing traffic problems of mobile terminals used in high-rise floors of buildings, the three-dimensional cell configuration which places small cells on various floors is considered. In order to evaluate wireless transmission technologies for the three-dimensional cell configuration, it is necessary to clarify the time-spatial characteristics of the path loss, delay profile...
In this paper, we proposed and evaluated the human detection system using UHF band TV waves for the car security. The measurements were performed in the parking space by the human detection system using software-defined radio with four receiving antennas. As a result, it was confirmed that human detections measured by the one receiving antenna were limited to specific areas such as vicinities of receiving...
In layered cellular networks, to avoid the frequent handovers (HOs) that occur between small cells when a high velocity mobile terminal (MT) travels through these small cells in a short period of time, an inter-layer HO control policy that connects an MT traveling at a high velocity to the macro-cell layer and an MT traveling at a low velocity to the small-cell layer, is effective. To realize such...
Isolation characteristics between white LED and image sensor in the transceiver for OOK were measured using two different LEDs to realize full-duplex and multiple-access visible light communication. No direct interference other than reflection from the receiver was observed and error free operations with BER of less than 10−4 were achieved for full-duplex and multiple-access visible light communication.
The behavior of power transmission of a normally incidence plane wave with TM polarization through subwavelength slits on Ag and Au plates from 1.2 THz to 200 THz is investigated for various plate thicknesses. The transmission patterns versus plate thickness by using mode matching technique are contrasted to those of a slit on perfectly conducting plate. The transmission physics at low frequency is...
In this paper, characteristic modes involved in smart phone are analyzed using the available CMA code in the comprehensive 3D electromagnetic field solver HW (HyperWorks) FEKO. A typical design workflow of characteristic mode analysis is considered to meet design specifications. It includes investigation of the structure, excitation of the correct modes, and verification of the design parameters....
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