Mark Godino

Date of Award

12-1993

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering

Department

Department of Electrical and Computer Engineering

First Advisor

Michael P. Clark, PhD

Abstract

Fighter aircraft equipped with X-Band radars having an adaptive beamforming capability exhibit degraded performance due to radome multipath reflection (RMR). The reflections from the radome into the antenna array degrade the pattern and cause the formation of large sidelobes. This phenomenon makes detection of LO targets difficult when jamming enters the high RMR sidelobes. Actual radomes are curved and cause reflected wavefronts to be nonplanar. Analyzing beamformer performance under these conditions is difficult, since the beamformer response is defined as the amplitude and phase change experienced by a complex plane wave as a function of frequency and location. To work with planar wavefronts and for the sake of simplicity, we model the radome as two flat plates parallel to array broadside (one at each end of the array). This radome model demonstrates degraded beamformer performance by causing large sidelobes to form. This approximates the characteristics of the multipath environment caused by a real radome. The ability of a linearly constrained, minimum variance beamformer to cancel interference arriving in the sidelobes is evaluated. The cancellation performance depends on how many taps are employed and the source frequency bandwidth. Results are provided for a linear, equally spaced sixteen element array.

AFIT Designator

AFIT-GE-ENG-93D-09

DTIC Accession Number

ADA274029

Comments

The author's Vita page is omitted.

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