Takayuki Sasamori

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.

Time domain analysis of crosstalk between microstrip lines placed along slot with various widths and lengths

The crosstalk between microstrip lines placed closely on a printed circuit board is an important problem. Recently, a slot which is formed in a ground plane induces undesired influence to the crosstalk between lines. Accordingly, understanding the influence of the slot is important. In this paper, the authors have analyzed the influence for the crosstalk between microstrip lines by changing widths and lengths of a slot using the FDTD method in time domain. Analysis results showed that the crosstalk increases as the width of the slot increases and time range in which the crosstalk increases expands as the length of the slot increases. Further, we measured the crosstalk between microstrip lines placed along the slot with various widths and showed that measurement result almost agrees with analysis 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.