Ray Tracing Algorithm for Indoor Propagation

The fields due to a portable radio operated inside a hospital are of interest because of possible interference with hospital equipment. This paper presents an algorithm for finding ray paths from a handset to an observer using an “image tree” data structure. The algorithm finds all ray paths having field strength at the observer above a preset “threshold” value, no matter how many reflections are involved. The method is applied to compute the fields due to a handset in a small room, and the results are compared with measured field strengths.