In this paper we will propose a deterministic approach to model the radio wave propagation channels in large empty buildings. This technique applies the modified SBR method to find equivalent sources (images) in each launched triangular ray tube, and sums the receiving amplitude contributed by all images coherently. In addition, vector effective antenna height (VEH) is introduced to consider the polarization coupling effect resulting from the multiple reflection inside the buildings. We verify this approach by comparing the numerical results in three canonical examples where closed-form solutions exist. The good agreement indicates that our method can provide a good approximation of high frequency radio propagation inside buildings where multiple reflection is dominant. Work reported in this paper has shown that propagation loss in large empty buildings can vary considerably according to the geometrical configurations of buildings and polarizations. This SBR/image method can be enhanced by including the wall penetration and wedge diffraction effects so that more complicated indoor environments with furniture will be handled. Additional considerations, such as buildings crowded with pedestrians are left for future studies.

As the demand of wireless personal communications networks increases, detailed chracteristics of indoor radio propagation in UHF band are required. In this paper, multipath fading characteristics at 1 GHz in an indoor mobil (walking speed) channel are investigated. By using a computer-controlled antenna scanner, signal strength was measured at 1400 points with a quarter wavelength resolution, which forms a two-dimensional fading map. The fading characteristics were found to be mainly dominated by the signals through the LOS path and the reflected paths due to two side-walls and one front-wall. It is analytically shown that middle-scale (over three wavelengths) fading is caused by the reflection from the side-walls, and periodical small-scale (equal to or less than a wavelength) fading is caused by the reflection from the front-wall. A software simulator based on geometric optics was developed in order to predict the measured fades. A modified algorithm for the two-dimensional ray launching technique which removes the necessity of checking the "multiple-counted rays" is presented. Comparison between measurements and predictions shows good agreement highlighting the usefulness of the two-dimensional simulator as a tool for channel design.

In this paper we will propose a deterministic approach to model the radio propagation channels complex indoor environments. This technique applies the SBR method to find equivalent sources (images) in each launched ray tube, and sums the receiving amplitude contributed by all images coherently. We verify our SBR/image approach by comparing the numerical results in two canonical examples where closed-form solutions exist. The good agreement indicates that our method can provide a good approximation of high frequency radio propagation inside corridors where reflection is dominant. In the special case of a curved corridor, which can not be solved by analytic methods, we find a "focusing" effect that at some certain point the receiver will receive high power, even though it is out of sight. This SBR/image method can be enhanced by including the wall penetration and wedge diffraction effects, and even more complicated indoor environments will be tackles in the near future.