Accession Number : AD0800339

Title :   TRANSEQUATORIAL F-LAYER PROPAGATION STUDY.

Descriptive Note : Final rept.,

Corporate Author : SMYTH RESEARCH ASSOCIATES SAN DIEGO CA

Personal Author(s) : Bowen, E. D. ; Fay, W. J. ; Heritage, J. L. ; Buss, J. R. ; Andersen, K. J. B.

Report Date : SEP 1966

Pagination or Media Count : 102

Abstract : This final report describes an experimental research program on the transequatorial, log range, VHF propagation in the Far East during the sun spot minimum. Four VHF frequencies, 34, 45.1, 54, and 77 MHz were transmitted from Okinawa and received at Darwin, Australia, and Lautoka, Fiji Islands. The Okinawa-Darwin path was 4300 km and oriented along a magnetic meridian, while the Okinawa-Fiji path was 7200 km long and formed an angle of 36 degree with the magnetic equator. The basic data obtained were signal strength, path loss, angle of arrival, pulse miltipath, and travel time measurements. The signal reception favors the north-south path by a 2 to 1 ratio at 34 MHz and larger ratios at higher frequencies. Disimilarities were observed between the diurnal variation of signal strength for Darwin and Fiji. Both receiving sites show minima in signal level at sunrise but Fiji activity peaks in the early afternoon while Darwin peaks in the early evening. The seasonal variation maximizes near the equinox with a pronounced minimum at the December solstice and only a slight minimum at the June solstice. Two modes were observed which are unique to the equatorial paths. The normal mode exhibits path losses close to free space loss, low elevation angle, and support of frequencies as high as 45 MHz. The anomalous mode supports frequencies through 77 MHz with frequency independent transmission loss through 54 MHz. It is characterized by rapid fading and is received at relatively low elevation angles (6 degree). The anomalous mode correlates well with rapid changes in magnetic indices Kp. (Author)

Descriptors :   (*IONOSPHERIC PROPAGATION, RADIO WAVES), VERY HIGH FREQUENCY, MULTIPATH TRANSMISSION, RADIO FIELDS, ANGLE OF ARRIVAL, VELOCITY, IONOSPHERE, DIURNAL VARIATIONS, RADIO TRANSMITTERS, RYUKYU ISLANDS, RADIO RECEIVERS, RADIO RECEPTION, AUSTRALIA, MELANESIA.

Subject Categories : Atmospheric Physics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE