This paper investigates radio wave propagation into buildings illuminated from an out- door
base station with an antenna above the rooftop. Field strength measurements are taken in four
buildings in urban microcells. Results of our experiments as well as those of several other authors
are analyzed and the important factors influencing building penetration loss have been discussed
namely angle of incidence, external wall configuration, receiver height and significance of
non-line-of-sight surface of the building.
