Accession Number : AD0437911


Title :   SPATIAL PROPERTIES OF AMPLITUDE FADING OF CONTINUOUS 17-MC RADIO WAVES


Corporate Author : STANFORD UNIV CA STANFORD ELECTRONICS LABS


Personal Author(s) : Ames, John W


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/437911.pdf


Report Date : Mar 1964


Pagination or Media Count : 108


Abstract : The experiment presented was undertaken in order to contribute to the understanding of the mechanisms of radio-wave fading and to suggest possible improvements in present techniques of alleviating the undesirable effects of such fading. Observations were made of the spatial distribution along the ground in the vicinity of a receiver of the magnitude of ionspherically propagated 17- mc, CW radio waves. The spatial distribution of signal amplitude is found to exhibit a degree of periodicity that varies inversely with path length. For a fixed path length the spacing along the ground between signal-amplitude minima decreases as the number of ionospheric reflections increases. A mathematical model is constructed that shows how the spacing and orientation of signal nulls depends upon the angular elevations and bearings of the incoming RF wave fronts. This model correctly predicts the spacing and orientation of nulls in observed periodic fading patterns if the arriving RF wavefronts are assumed to be deviated a few degrees to the south of the great circle by a small north-south downward tilt in the structure of the ionosphere.


Descriptors :   *RADIO WAVES , ATTENUATION , EXPERIMENTAL DATA


Subject Categories : Radiofrequency Wave Propagation


Distribution Statement : APPROVED FOR PUBLIC RELEASE