ELECTROMAGNETIC WAVES BY COMPLEX OBJECTS

THE ABILITY TO COMPUTE EFFICIENTLY THE SCATTERED ELECTROMAGNETIC WAVES (RADAR CROSS SECTION) BY A TARGET WITH COMPLEX GEOMETRY AND MATERIAL PROPERTY (INCLUDING ANISOTROPY, FINITE CONDUCTIVITY, ETC.) PLAYS A VERY IMPORTANT ROLE IN ADVANCED VULNERABILITY ANALYSIS FOR ANY POSTULATED AIRCRAFT. HENCE THE DEVELOPMENT OF AN EFFICIENT AND VERSATILE NUMERICAL ALGORITHM FOR SOLVING THIS TYPE OF COMPLEX EM SCATTERING PROBLEMS IS DEFINITELY IN DIRE NEED. IT IS PROPOSED TO ACHIEVE THIS BY USING A SPECIAL FINITE DIFFERENCE METHOD BASED UPON A NATURAL SPATIAL DISCRETIZATION OF THE INTEGRAL FORM OF MAXWELL'S EQUATIONS ON A NON-ORTHOGONAL GRID-SYSTEM AND THE LEAD-FROG FINITE DIFFERENCING IN THE TIME DOMAIN. IT HAS THE ADVANTAGES OF BEING (A) MORE EFFICIENT THAN ANY OTHER KNOWN NUMERICAL METHODS, (B) HIGHLY ACCURATE DUE TO THE BODY-FITTED GRID-SYSTEM, AND (C) THE EASIEST NUMERICAL METHODS TO IMPLEMENT ANY BOUNDARY CONDITIONS. IF THERE IS A NEED, FAST FOURIER TRANSFORM OF THE CORRESPONDING RESULTS IN THE TIME DOMAIN. THE PHASE I EFFORTS ARE TO DEVELOP THE ABOVE-MENTIONED EFFICIENT NUMERICAL ALGORITHM FOR SOLVING TWO-DIMENSIONAL SCATTERING PROBLEMS AND TO DEMONSTRATE ITS CAPABILITY BY SOLVING MANY REALISTIC EXAMPLES.