Spectrum Engineering

This is the fourth part of a four-part report containing tabulations and graphs of transmission loss data resulting from propagation experiments in the 230 - to 9200-
MHz frequency range conducted over irregular terrain in Colorado. This part presents data obtained at a Common receiver site, located in a small grove of cottonwood
(Populus deltoides) trees, over propagation paths varying in length fro 0.5 to 50 km.

Key Words: UHF propagation data, irregular terrain, UHF
propagation through trees

This report documents a digital computer program for computing the propagation of LF and VLF radio waves using the wave hop theory. It supersedes NBS Report 8889. The documentation includes a description of the physical model, detailed mathematical formulas, a main function flow chart, a listing of the FORTRAN source deck, and the input and output of a sample case.

This report summarizes measurements of tropospheric transmission loss and its long-term variability for nearly 800 paths in various parts of the world. The measurements were made at frequencies from 40 MHz to 10 GHz over distances which range from 10 to 1000 km. Terrain profiles and cumulative distributions of both observed and predicted losses are plotted for more than 500 of these paths. A preliminary analysis of differences between observed and predicted values is included.

Key Words: Cumulative distributions, location variability, long-term variability, measurements, predictions, tropospheric propagation.