July 1984 | NTIA Technical Report TR-84-151
Jean E. Adams; John C. Carroll; E. A. Costa; Donald R. Ebaugh Jr.; John R. Godwin; Eldon J. Haakinson; Donald H. Layton; Darren L. Smith
Abstract: Measurements of radio propagation path loss were made over four paths in the 3 to 30 MHz band. The paths were of lengths up to 45 km in the Boulder, CO, area. They ranged from smooth to mountainous terrain, from open areas with few or no man-made structures to suburban areas with building heights up to three stories, and from open spaces with little vegetation to heavily forested regions. On one path, measurements were made with and without snow cover. The measurements were made in the daytime and because of the short paths, the primary mode of propagation was ground wave. Measurements of the ground constants at each of the four measurement frequencies were made at the transmitter site using the wave-tilt measurement technique. One objective of gathering the HF propagation data was to compare the measurement results with ground wave propagation predictions made by a computer program that used the path profile, ground constants, and frequency as prediction parameters. The results of the predictions and the comparisons with the measured data are discussed. Another objective of the measurement project was to describe the measurement technique and procedure in sufficient detail so that similar measurements could be made by others. The measurements were made with a fixed transmitter and mobile receiver and data collection system. Since measurements were made continuously while the receiver van was in motion, position location information was determined by recording the vehicle's speedometer shaft rotation. Antenna gain measurements were made and are presented for the transmitter antenna on a partial ground screen and for the receiver antenna mounted on a van.
Keywords: HF ground wave; predictions and measurements; propagation path loss; ground constants measurement; wave-tilt technique; irregular; inhomogeneous terrain; ground screen measurements; mobile measurements; HF antenna
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