Accession Number : ADA267105


Title :   Johnson-Gierhart Program Predictions of Excess Propagation Loss for Super-High Frequency Air-to-Ground Paths. Volume 1. Theory and Numerical Results


Descriptive Note : Final rept.


Corporate Author : MITRE CORP BEDFORD MA


Personal Author(s) : Weiner, M M ; Herther, J C


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a267105.pdf


Report Date : Jun 1993


Pagination or Media Count : 141


Abstract : The Johnson-Gierhart tropospheric propagation program of the Institute for Telecommunications Sciences is used to obtain predictions of excess propagation loss over that of free space for super-high frequency (SHF) air-to-ground paths within or on the radio horizon. The principal loss (gain) mechanisms considered are atmospheric absorption and refraction, surface multipath interference, smooth spherical Earth diffraction, and single knife- edge diffraction caused by terrain roughness and/or a site-specified obstacle. The program uses a semi-empirical database to statistically weigh the losses from these mechanisms. The excess propagation loss increases with increasing range and can exceed 3 decibels-at distances as close as halfway to the radio horizon.... Air-to-Ground, Langley-Rice, Excess Propagation Loss, Prediction Program, Johnson-Gierhart


Descriptors :   *SUPERHIGH FREQUENCY , *TROPOSPHERIC SCATTER COMMUNICATIONS , DATA BASES , PROPAGATION , PREDICTIONS , SITES , PATHS , SURFACE ROUGHNESS , TERRAIN , DIFFRACTION , RADIATION ABSORPTION , AIR TO SURFACE , GAIN , INTERFERENCE , RADIO EQUIPMENT , RADIO LINKS , TELECOMMUNICATIONS , LOSSES , ATMOSPHERIC REFRACTION , HORIZON


Subject Categories : Radiofrequency Wave Propagation
      Radio Communications


Distribution Statement : APPROVED FOR PUBLIC RELEASE