Vinod D. Naga

Date of Award

12-1997

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Electrical and Computer Engineering

First Advisor

Byron Welsh, PhD

Abstract

This thesis examines the effects of atmospheric turbulence-induced phase perturbations on the performance of ground-based Space-Time Adaptive Processing (STAP) systems. Both Fully Adaptive Joint Domain Optimum and Partially Adaptive Factored-Time Space processing methods are examined. This thesis concentrates on the turbulence effects on STAP applied to ground-based arrays. This thesis further focuses on the capability of STAP to resolve targets at low elevation angles in the presence of turbulence. Only clutter interference and receiver noise are considered. Turbulence effects on the EM phase-front are calculated for turbulence strength Cn(2) values ranging from 5.0 x 10(exp -14) m-2/3 to 5.0 x 10(exp -10) m-2/3 in the S, X, and Ka frequency bands. The analysis is carried out for array lengths of 32, 64, and 200 antenna elements at each frequency. The performance losses are summarized in terms of the signal-to-interference-plus-noise ratio (SINR) and the SINR Loss (LSINR). Fully adaptive performance losses due to atmospheric turbulence are less than 1 dB for typical turbulence strengths. The 200 element array faces a 6 dB performance loss at 30 GHz under turbulence of Cn(2) = 5 x 10(exp -12) m-2/3. Similar losses are recorded for Factored Time-Space and for all experiments where sampling of the interference through turbulence is simulated.

AFIT Designator

AFIT-GE-ENG-97D-09

DTIC Accession Number

ADA336421

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