Measuring Tropospheric Propagation in the 21st Century

This article is intended to motivate and describe a new tropospheric scatter modelling and measurement validation effort that is underway at the Institute for Telecommunication Sciences (ITS). Immediately after World War II, there was a flurry of research conducted to investigate the phenomenon of forward scattering through the troposphere, or troposcatter, for over-the-horizon radio links. During the early 1950s, ITS researchers carried out an extensive measurement campaign now summarized in the ITS technical report Cheyenne Mountain Tropospheric Propagation Experiments [1]. Several propagation models were developed from this effort as well as from similar follow-on measurement campaigns, such as the Irregular Terrain Model (ITM) and IF-77 (ITS-FAA air-to-ground propagation model, circa 1977). These models are based on simplified assumptions, but they are still used in today's spectrum policy decisions. ITS engineers are currently developing a modern measurement system that incorporates the latest RF hardware capabilities and takes advantage of the extensive information now available about our meteorological and geographical environment to improve the accuracy of these models. This paper describes the current and proposed deployments of this modern and upgraded ITS troposcatter measurement system.