Abstract :
Widespread v.h.f. continuous signal-strength measurements made in tropical and Mediterranean regions over the last four years have exemplified and thrown into relief many of the well-known mechanisms of tropospheric propagation. Although these mechanisms are broadly familiar to many engineers and physicists, the practical magnitudes, as exemplified throughout the paper, are perhaps less widely appreciated despite their great importance to the communication engineer. It is the purpose of the paper to present and analyse new v.h.f. data from the sources indicated, so as to show (a) that observed v.h.f. signal patterns are consistent with tropospheric structures known commonly to occur, and (b) that sufficient information is now available to enable the communication engineer to forecast to a useful accuracy the statistical behaviour of projected v.h.f. radio paths in certain parts of the world.