Characterization of tropospheric scintillations on Earth-space paths in the Ku and Ka frequency bands using the results from the Virginia Tech OLYMPUS experiment

There has been increasing interest in the use of Very Small Aperture Terminals (VSATs) in satellite communication links operating in the Ku and Ka bands. Such systems offers the advantage of low signal margins and therefore, low cost. For the same reason, however, VSATs links can be strongly impaired by tropospheric scintillations. The VA Tech OLYMPUS propagation experiment which includes 12, 20, 30 GHz beacon receivers at an elevation angle of 14° provides us with valuable multi-frequency scintillation data. This dissertation focuses on the characterization of tropospheric scintillations on earth-space paths. Tropospheric scintillations are rapid fluctuations of signal caused by multiple scattering from the sma11 scale turbulent refractive index inhomogeneities in the troposphere. Analysis of the scintillation results from the VA Tech OLYMPUS experiment for both short term and long term studies is presented. The results include spectral characteristics, frequency scaling and statistics of the scintillation intensity, statistics of scintillation fading, diurnal and meteorological trends as well as a comparison with the current CCIR predictive model. Sma11 scale spatial diversity is a potential means to counteract tropospheric scintillation fading; it can be cost effective because of the low cost of VSATs. The VA Tech experiment includes 12, 20, 30 GHz beacon receivers and colocated 20 and 30 GHz diversity receivers that allows us to study this restoration technique. In this dissertation the effects of spatial diversity are studied through a cross-correlation analysis. Experimental results are compared to a theoretical model in which the atmosphere is characterized by an "anisotropic" Kolmogorov spectrum. A method to determine minimum vertical spacing between terminals to achieve good diversity performance is introduced.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Electrical Engineering

Department dc:contributor.department

Electrical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1993

Author dc:creator

• Haidara, Fatim M.

Chair dc:contributor.committeechair

• Bostian, Charles W.

Committee members dc:contributor.committeemember

• Kohler, Werner E.
• Beex, A. A. Louis
• Pratt, Timothy J.
• de Wolf, David A.
• Stutzman, Warren L.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-06062008-170624

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/38423