T. Murasaki

Tokyo Institute of Technology, Edo, Tokyo, Japan

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Publications (6)0.93 Total impact

  • M. Ando · M. Oodo · T. Murasaki · M. Sato
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    ABSTRACT: Uniform physical optics (PO) diffraction coefficients are presented for skew incidence. They reveal for the first time that PO accurately predicts polarisation near the geometrical boundaries
    No preview · Article · Mar 1995 · Electronics Letters
  • M. Oodo · T. Murasaki · M. Ando
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    ABSTRACT: Uniform diffraction coefficients of PO (physical optics) for impedance surfaces are derived, and accuracy is checked. These diffraction coefficients reveal that PO has no polarization conversion at SB/RB geometrical optics boundaries and this fact is numerically checked
    No preview · Conference Paper · Aug 1993
  • M Ando · T. Murasaki · Y. Inasawa · M Sato · K. Natsuhara
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    ABSTRACT: A method of modified edge representation (MER) for flat plates are applied for the pattern analysis of GPS patch antennas mounted on a rectangular ground plane. In the MER, the contribution of FW-EECs (equivalent currents) to total EECs are weighted by the function of the angle between the modified edge and the real edge. The key feature of this approach is that uniform fields are predicted everywhere though only classical diffraction coefficients are used in first-order diffraction. The secondary diffraction is included as well. The ray-tracing is greatly simplified by introducing other fictitious edges for MER. Numerical results for diffraction from the GPS patch antenna mounted on a flat plates demonstrate the potential of MER. The EECs derived are specially refined to MER; the physical meaning of the MER and the weighting of FW-EECs should be validated theoretically in future study
    No preview · Conference Paper · Feb 1993
  • T. Murasaki · M. Ando
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    ABSTRACT: An explicit expression of PO-EECs (physical-optics equivalent edge currents) based on the concept of modified edge is derived. The magnetic equivalent edge currents according to this concept contain the term excited by the edge component of electric fields of the incident wave, in contrast to other PO-EECs. It is also numerically demonstrated that different PO-EECs give the same diffracted fields in plane wave incidence. This arbitrariness of PO-EECs may exist even if the source is close to the scatterer
    No preview · Article · Jan 1992
  • M. Ando · T. Murasaki · T. Kinoshita
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    ABSTRACT: The method of equivalent edge currents (MEC) has extended the applicability of GTD. The equivalent edge currents, however, generally suffer from false singularities outside the Keller cone. These singularities depend upon the coordinate for inner integration in the surface to edge integral reduction. The objective of this paper is to eliminate false singularities of the currents. A new co-ordinate for inner integration that maximises the phase variation of the integrand is proposed. Consistent use of this co-ordinate leads us to novel expressions for not only fringe but also PO and GTD equivalent edge current without any false singularities. These currents are verified for diffraction from a disk and a square plate. It is numerically confirmed that GTD-MEC using new currents predicts uniform patterns and is almost comparable to PTD
    No preview · Article · Sep 1991 · Microwaves, Antennas and Propagation, IEE Proceedings H
  • M Ando · T. Murasaki · T. Gokan
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    ABSTRACT: The authors propose a novel and heuristic concept for surface to edge integral reduction of physical optics currents in order to obtain PO-EECs (physical-optics equivalent edge currents) without false singularities. Firstly, the edge of the scatterer is divided into segments, each of which is replaced with a fictitious one satisfying the diffraction law at each point. Secondly, classical PO diffraction coefficients are applied to the fictitious edge, and the EECs with only the true singularities are derived. The remarkable accuracy of PO-EEC is demonstrated numerically for dipole-wave diffraction from a flat disk and a square plate. It is noteworthy that the residual current singularity at shadow/reflection boundaries can also be suppressed arbitrarily by taking the limit in the subsequent line integration; uniform PO fields are predicted everywhere
    No preview · Conference Paper · Jul 1991