Paul C. Lash

Date of Award

3-2006

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Electrical and Computer Engineering

First Advisor

Michael J. Havrilla, PhD

Abstract

Radar cross section (RCS) prediction of full-scale aircraft is of interest to military planners for a variety of applications. Several computational electromagnetic codes for RCS prediction are available with differing features and capabilities. The goal of this research is to compare the capabilities of three computational electromagnetic codes for use in production of RCS signature assessments at low frequencies in terms of performance, accuracy, and features: Fast Illinois Solver Code (FISC), Code for Analysis of Radiators on Lossy Surfaces (CARLOS-3D), and Science Applications International Corporation Full-wave solver (SAF). The comparison is accomplished through analysis of predicted and measured RCS of several canonical and simple objects and a complex target comprised of these constituent objects. In addition to RCS accuracy, memory requirements and computation time are key considerations for this code comparison. Verification of code performance in memory and processing time based on varying levels of unknowns is performed. A 1/36 scale body-of-revolution missile model is the complex model constructed for measurement and prediction. The model corresponds to an 18-meter full-scale target and includes a cavity allowing mode propagation at frequencies of interest. The complex model is simulated at 400 and 500 MHZ corresponding to a 24 and 30 lambda target length, respectively. RCS of each constituent part of the model is also analyzed to establish a level of confidence in solution accuracy. Solution convergence is shown using increasing discretization levels. A comparison is also conducted between measured and predicted results for two PEC objects coated with magnetic radar absorbent material (MRAM). The RCS for a 12″×12″ MRAM-coated PEC flat plate and a 9″×9″ MRAM-coated PEC right circular cone are measured in the Air Force Research Laboratory’s compact RCS/antenna measurement range and then compared to results from FISC using its impedance boundary condition (IBC) feature. A physical optics method for predicting RCS of a material-coated PEC plate is also developed as a third data. The IBC formulation is generalized for polarization and angle-dependent impedances to investigate prediction improvement. Results of each part of the comparison are presented as well as the methodology used to evaluate the codes.

AFIT Designator

AFIT-GE-ENG-06-32

DTIC Accession Number

ADA451781

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