JaLCDOI 10.18926/47029
FullText URL mfe_36_2_083_089.pdf
Author Watanabe, Tetsushi| Wada, Osami| Koga, Ryuji| Toyota, Yoshitaka| Miyashita, Takuya|
Abstract Suppression of common-mode current is important to achieve electromagnetic compatibility of high-speed and high-density electronic circuits. The authors have focused on the common mode current flowing on a printed circuit board (PCB) to explain the excitation mechanism. A narrow ground pattern in microstrip structure excites common-mode current. In the previous paper, the authors explained the mechanism of common mode generation by means of "current division factor" for simple PCBs. The estimated radiation from a simple PCB agreed well with measured one. In this paper, the authors extend the theory to be applied to generalize ground structure. The validity of the theory is confirmed by comparing the measured radiation and the estimated value using the common-mode model for a test PCB. The estimated radiation agrees well with the measured one within 3 dB up to 900 MHz.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2002-03
Volume volume36
Issue issue2
Start Page 83
End Page 89
ISSN 0475-0071
language 英語
File Version publisher
NAID 120003497051
JaLCDOI 10.18926/47028
FullText URL mfe_36_2_073_082.pdf
Author Hidayat, Iip Syarif| Toyota, Yoshitaka| Torigoe, Osamu| Wada, Osami| Koga, Ryuji|
Abstract A multi-path ring-resonator (MPRR) was proposed to extend FSR of ring resonator. However, it is complicated to analyze the MPRR by using well-known analysis techniques such as scattering matrix or other numerical methods. This paper describes procedure for deriving transfer matrix by means of signal flow-chart to analyze the MPRR. We do not need complicated calculation for steady state analysis because transfer matrix elements are formulated clearly. As a result, The calcultaion time in this method can be reduced 1/3 to 1/20 times compared with using scattering matirx method. Furthermore, a transmittance characteristics of the MPRR at FSR extension-factor of 10 will also be shown. This suggests that analysis of other types of the MPRR by using this method can be performed simply and take a shorter time.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2002-03
Volume volume36
Issue issue2
Start Page 73
End Page 82
ISSN 0475-0071
language 英語
File Version publisher
NAID 120003497050
JaLCDOI 10.18926/46983
FullText URL mfe_37_2_089_097.pdf
Author Iokibe, Kengo| Toyota, Yoshitaka| Wada, Osami| Koga, Ryuji|
Abstract Aerosol extinction coefficients of clouds and dust were continuously measured in the year of 2002 with a polarized Mie-scattering lidar controlled by an automatic and remotely operating system utilizing internet services. Measured cloud extinctions were greater than 1.0 km(-1) below the altitude 6 km, 0.17 - 1.0 km(-1) between 6 and 10 km, and 0.091 - 0.3 km(-1) beyond 10km. Extinction of dust were 0.10 and 0.20 km(-1) for Asian dust and 0.057 km(-1) for urban dust.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2003-03
Volume volume37
Issue issue2
Start Page 89
End Page 97
ISSN 0475-0071
language 英語
File Version publisher
NAID 120003457336
JaLCDOI 10.18926/46972
FullText URL mfe_37_1_051_060.pdf
Author Namba, Akihiro| Toyota, Yoshitaka| Wada, Osami| Koga, Ryuji|
Abstract This paper presents pulse timing control method to reduce electromagnetic emission from multiple signal interconnections. Pulse timing control gives intentional skew between signals. Higher order harmonics are canceled because of the difference of the phase between the signals. Using this property, pulse timing control can reduce the EMI in wide frequency range. In this paper, we show that radiated electromagnetic field from multiple signal lines reduces its intensity to the same level of the field from one line by using pulse timing control. The result of measurement shows that EMI from four differential transmission lines can be reduced more than 9 dB in the 200 MHz to 800 MHz frequency range.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2002-11
Volume volume37
Issue issue1
Start Page 51
End Page 60
ISSN 0475-0071
language 英語
File Version publisher
NAID 80015683518
Author Wang, Zhi Liang| Wada, Osami| Toyota, Yoshitaka| Koga, Ryuji|
Published Date 2005-2
Publication Title Electromagnetic Compatibility
Volume volume47
Issue issue1
Content Type Journal Article
Author Wang, Zhi Liang| Wada, Osami| Toyota, Yoshitaka| Koga, Ryuji|
Published Date 2003-11
Publication Title Environmental Electromagnetics
Content Type Journal Article
Author Wang, Zhi Liang| Wada, Osami| Toyota, Yoshitaka| Koga, Ryuji|
Published Date 2002-5
Publication Title Electromagnetic Compatibility
Content Type Journal Article
JaLCDOI 10.18926/15360
FullText URL Mem_Fac_Eng_OU_34_27.pdf
Author Wei, He| Koga, Ryuji| Iokibe, Kengo| Wada, Osami| Toyota, Yoshitaka|
Abstract In spring of 1998, Asian dust was observed with a Mie LIDAR in Okayama University, which can measure depolarization ratio. Three events of intense Asian dust were occurred in the period and medially detailed structure of atmosphere was found after examining records. Asian dust was distinguished from water droplets and the possibility to study three dimensional dynamic structure of atmosphere were demonstrated.
Keywords Mie lidar Asian dust (KOSA) depolarization ratio backscattering ratio range normalized
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2000-03-27
Volume volume34
Issue issue1-2
Start Page 27
End Page 37
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307539
JaLCDOI 10.18926/14158
FullText URL Mem_Fac_Eng_39_1_93.pdf
Author Iokibe, Kengo| Toyota, Yoshitaka| Wada, Osami| Koga, Ryuji|
Abstract The optical properties of clouds were measured with a polarization Mie lidar during April, 2004 and investigated to categorize the particles detected by the lidar. The cloud layers were categorized into five types according to the depolarization ratios, as follows: (I) constant and small (less than 5%); increasing with height (II) nearly from 0% and (III) from about 50%; (IV) large and varying with the backscattering coefficient; and (V) sharply decreasing. This categorization of clouds enabled us to separate aerosols from clouds in a lidar signal. Comparison of the backscattering coefficients between clouds of types (I) and (II) suggested that the depolarization ratio induced by multiple scattering in dense clouds does not depend on the particle density. Estimation of the particle phase for the five cloud categories was also examined.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2005-01
Volume volume39
Issue issue1
Start Page 93
End Page 101
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308479