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For design of optimum microcells on a university campus, it is necessary to determine the propagation characteristics within a propagation environment represented by a relatively large open space scattered with large buildings and many trees. In this paper, for the radiated waves from seven PHS base sites at 1.9 GHz experimentally installed on the campus of Hokkaido University from 1993 to 1994, a median received signal level measurement method is proposed that can be applied in unpaved garden areas (with glass and pebbles) as well as in areas with woods, vegetation, and hilly terrain, and its effectiveness is discussed. Next, for quantitative evaluations of the increase of the propagation loss due to trees in the propagation paths on the campus, a propagation model is proposed that consists of the loss layer model and the geometrical optics two-ray model. In the loss layer model, the loss due to trees is replaced with a loss per unit length of the propagation path. The estimated median received signal level and the measured value are compared to determine the effectiveness of the model. The increase of the propagation loss on the campus due to trees can be estimated if the loss per unit length of the tree layer by the present loss layer model is chosen to be about 0.1 dB/m for the base site antenna installed on the rooftop of the building and 0.07 to 0.09 dB/m for the antenna installed on the roof of the public phone box. © 2001 Scripta Technica, Electron Comm Jpn Pt 1, 84(8): 49–61, 2001 [ABSTRACT FROM AUTHOR]

The attenuation due to rainfall in tropical regions has generated more concern in recent years. In Singapore, a microwave propagation experiment of line-of-sight communication has been conducted, and some experimental results have been obtained. The specific rainfall attenuation and rain attenuation duration temporal cumulative distributions over a ten-month period for 15 and 38.6 GHz are analyzed in this paper. The frequency scaling relationship between distributions is also discussed in detail. The results obtained in Singapore's tropical environment are found to be quite different from the CCIR's predictions. The results of our experiment can be employed to guide the design and application of terrestrial microwave communication systems, especially in tropical regions. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 470–473, 1999. [ABSTRACT FROM AUTHOR]

Continuous current spectrum of an integrated open waveguide structure is identified as the branch cut contribution to singularity expansion of those currents in the complex axial transform plane. Those singularities in that plane include poles associated with the guiding structure and branch points contributed by layered background environments. The manner in which singularities in background environments manifest themselves as branch points in the complex axial transform plane is reviewed. Based on spectral integral equation formulation, approximate and analytical expression for spatial microstrip current is obtained. That approximation is based on Maxwellian distribution for the transverse current profile. This result is the representation of currents in terms of proper propagation mode spectrum. During the integration around branch cuts, singularities in the transverse transform plane migrate in a complicated manner. The trajectories of this migration are identified and suitably accommodated during the real axis integration in that plane. This overall procedure leads to a decomposition of the total currents into bound modes and continuous spectrum contributions. This representation is validated by real axis integration in the axial transform plane. The quasi TEM characteristic impedance of bound mode is calculated and validated by comparison with well-known empirical formula. [ABSTRACT FROM AUTHOR]