Hae-Won Son

A deterministic ray tube method for microcellular wave propagation prediction model

In this paper, we present a new and very fast ray-tracing method using a ray tube tree, which is based on uniform geometrical theory of diffraction (UTD) and can solve some of the problems that other ray-tracing methods have. It is developed for quasi three-dimensional (3-D) environments and can be applied to any complex propagation environment composed of arbitrary-shaped buildings and streets. It finds all propagation paths from a transmitter to a receiver extensively with very high computation efficiency. It is fundamentally a point-to-point tracing method, so reception tests are not required and it guarantees high accuracy. To validate our ray-tracing method, signal path loss and root mean square (rms) delay spread were computed in the downtown core of Ottawa, Canada, and they were also compared with the published measurements. The results of the proposed method in this paper show good agreement with the measurements. The computation time required to obtain a path loss map in the site is revealed to be very short in comparison with other methods.

Radiation Efficiency Improvement of RFID Tag Antenna for Metallic Objects Printed on Lossy Substrate

In this paper, we propose a new antenna design method for RFID tass on metallic surfaces using a low-cost, high-loss substrate such as FR4. The proposed design method highly reduces the substrate loss due to its dielectric loss, and so improves the radiation efficiency of the tag antenna more than double compared with a conventional PIFA(planar inverted-F antenna). The equivalent circuit model of the antenna according to the proposed method was established and its characteristics were analyzed systematically in this paper. The excellency of the proposed design method was verified by the fabrication and measurement of a prototype antenna.