For wireless communication system in urban area, received signal level is important in determining the coverage of the system. This paper presents a model to predict the field strength level on streets inside a campus with steep terrain due to a UTMS base station at 949.2 MHz on rooftop using 3D ray tracing method. Measurements is conducted using isotropic antenna to calibrate the transmit power of antenna in the model. With the simulation model, the field strength around the campus is computed.