Physical optics, or Fresnel-Kirchhoff theory, is often used for studies of particular problems in terrestrial radio-wave propagation. With efficient techniques of numerical integration, it can also be used effectively for routine predictions and for designing terrestrial wireless systems. A computer program of this type has been in use for several years. It is most useful in situations in which the base station (BS) antenna is above local clutter, and over areas large enough that ground cover can be characterized with categories such as "open," "forest," "dense residential," etc., rather than individual buildings. The main calculation is a marching algorithm that simulates diffraction over all the variations in terrain height along radials from the BS. A secondary calculation estimates the additional attenuation due to buildings and trees close to the mobile antenna. This part of the calculation is based on several parameters characterizing the local environment of the mobile antenna. Calculations are slow compared to many traditional methods, but are fast enough for routine use on a PC. Index Terms-land mobile radio propagation factors, physical optics, radio propagation, radio propagation terrain factors, ultrahigh frequency radio propagation terrain factors. James H. (Jim) Whitteker received the B.Sc. degree from Carleton University, Ottawa, in 1962, and the Ph.D. degree in physics from the University of British Columbia, in 1967. He was a postdoctoral fellow at University College London in 1967-1969, working in atomic collisions. He worked at the Communications Research Centre in Ottawa from 1969 to 1999. For the first ten years, his work was on the structure and dynamics of the polar topside ionosphere. For the next 20 years, he worked on VHF and UHF terrestrial radio-wave propagation, and on related topics including topographic data. In 1999, he joined Northwood Technologies, which is now part of Marconi, to do research and development in radio-wave propagation. His particular interest is the use of physical-optics techniques for calculating diffraction attenuation due to terrain obstructions.