Kohshi Abe

A Study on Miniaturization of Printed Disc Monopole Antenna for UWB Applications Using Notched Ground Plane

In this paper, we report the detailed investigation of novel printed disc monopole antennas for ultra-wideband (UWB) applications focusing on miniaturization of the disc radiator. First, the basic property was examined for the case of a circular disc with diameter of 50mm, and it was found that the VSWR is less than 2 in the UWB band of 3.1-10.6 GHz when the feed gap length is between about -0.1 and 0.2mm. Next, in order to reduce the size of the disc radiator, various dimensions of elliptical discs were investigated. It is shown that if the dimensions of the elliptical disc are chosen appropriately, a smaller disc size antenna can be achieved. To decrease the antenna size further, a triangular notch and an exponentially curved notch on the ground plane of the antenna were examined. It is observed that the use of the notched ground is very effective and that the diameter of the circular radiator can be reduced to 17 mm. The proposed antenna has an omnidirectional pattern in the x-y plane. The influence of the notch on the radiation pattern is very small. Details of the simulation results using the FDTD method and experimental results for the proposed antenna are presented and analyzed. These features are very attractive for UWB applications.

Miniaturization of Printed Elliptical Disc Monopole Antennas for UWB Applications

In this paper, we describe improved designs of a printed disc monopole antenna for UWB application, focusing on miniaturization of the disc radiator with the size of the ground fixed. In order to decrease the antenna size, an exponentially curved notch on the ground plane of the antenna was investigated, and the optimal design of the shape of notch verified. By appropriately adjusting the size of the notch, the VSWR characteristics of the antenna clearly can be improved. Our investigation has shown that the diameter of the circular radiator can be reduced to 15 mm by using the exponentially curved notch. The antenna has a nearly omnidirectional radiation pattern, like a traditional monopole. These features are very attractive for UWB applications.

A study on a road-vehicle communication system for the future intelligent transport systems

This paper presents an example of a future intelligent transport system (ITS) and the results of the examination of the system configuration. It proposes a road-vehicle communication system for the future ITS. As an evaluation of the proposed system, propagation characteristics of the radio link using 45 GHz band millimeter-wave are examined, such as the vehicular interval for the line-of-sight communication, the received power level at the mobile station in adopting the transmitting power control and the diversity and attenuation caused by rain, which will clarify the feasibility of this system.

Suppression Effect of Emission from Printed Circuit Board Using Conducting Plate

For emission from a printed circuit board (PCB) by the common-mode current the suppression method based on the image theory by placing a conducting plate under the PCB is presented. In order to evaluate the suppression effect by this method the radiation power from the PCB is calculated by using FDTD method. The numerical results show that placing the conducting plate near the ground side of the PCB suppresses effectively the emission by the common-mode current. Especially, using the conducting plate bent the sides, it is possible to suppress the emission by the small conducting plate. Moreover, the method by bending the edges of the PCB is presented and is showed that large suppression effect is obtained using this method. Further, the experimental results of a maximum electric field intensity show the validity of the numerical results.

Analysis of Emission from Printed Circuit Board with a Conducting Wire Directed to Various Directions

Emission from a printed circuit board (PCB) with a finite size becomes serious when the common mode current is excited on it. Such the common mode current can be occurred at connections of conducting wires, or at a discontinuity of a line or a ground plane on a PCB. In order to clarify a relation between connected a conducting wire to emission, the authors analyzed emission from a PCB connected a conducting wire directed to upper or lower direction at the ground edge using finite difference time domain (FDTD) method. From numerical results, it is shown that in case of a conducting wire connected to upper direction, the radiation power is the largest. Moreover, for the position of a microstrip line, the radiation power is the largest when the distance between the microstrip line and the wire is small. Further, the experimental results of radiation power show the validity of the numerical results.

Suppression Effect by Conducting Plate under Ground Plane for Emission from Printed Circuit Board

A pair of interlocking single filament or multifilament loops (6,7) are mounted on the opposed operating ends (4,5) of a pliers action type hand tool. An aperture is formed between the two loops through which an optical fibre (31) complete with soft plastics primary coating (32) is inserted. The loops are tensioned by operation of the tool, and while this tension is maintained the fibre is removed causing the coating to be stripped off by the tightened loops.

Reduction of the induction field on overhead transmission lines caused by MF broadcast wave

The induction field caused by MF broadcast waves can occasionally be a safety concern during maintenance and inspection work on transmission lines. In this paper, we examine a coil grounding and we put forward a method of selecting ground points (steel towers) with the aim of reducing the induction field and thereby ensuring better safety. The frequency characteristics of the field strength is obtained by numerical calculation. In addition, the effectiveness of the grounding methods is confirmed by showing the measurement result and the calculation result of the field strength in the vicinity of the bottom conductor.

Suppression effect of the emission from printed circuit board using magnetic absorber located along microstrip line

The effect of suppressing electromagnetic emission from a printed circuit board (PCB) with a microstrip line by using a magnetic absorber located along the microstrip line is investigated. On calculation, a ferrite plate with the Debey dispersion is used as a magnetic absorber. The PCB consists of an infinite ground plane, dielectric substrate and a microstrip line terminated with an open, short or 50 /spl Omega/ load. The frequency dependent finite different time domain (FD-FDTD) method is used for the numerical analysis. The calculated results suggest that the suppression effect is achieved by a magnetic absorber is placed at a large magnetic field intensity. The analysis results are confirmed with the measured results using another magnetic absorber.