Diffraction techniques are used to predict the propagation path loss between a radio transmitter site and receiver sites located on flat land, in the shadow of mountainous and hilly terrain, near wooded areas and within several types of building structures. These predictions are used to determine the effective coverage range for a radio paging service and, in the reverse problem, are used to determine the required transmitter power and siting for a desired geographical coverage. Extensive field tests at over 50 sites and ranges to 50 km are summarized for comparison with predicted values.