- In this work, we continue the analysis of a unified probabilistic approach and the corresponding stochastic multiparametric model of wave propagation above the terrain, including microcell, rural forested, mixed residential and urban, environments. Taking into account diffraction effects caused by the Earth's curvature, we extend this model to the radio links with ranges of more than 10 km covering rural macrocell communication and describe effects of interference caused by terrain curvature. We concentrate on path loss dependence in the frequency domain within the UHF/X-band propagation channels both for urban and rural areas and on link-budget design in such types of communication links. It is shown that the frequency dependence of loss and fading characteristics in terrestrial communication links depend significantly on terrain's topography, all features of obstructions, natural and man-made, as well as on the terminal antennas elevation with respect to obstruction surrounding. Then, based on the same stochastic approach, we give practical recommendations on how to design the link budget based on the concept of fast fading, shadowing effects, and average path loss within various terrestrial communication links and compare them with existing approximate prediction methods.