Comparison of asymptotic methods for predicting the electromagnetic scattering from engine cavities

The authors document the results of the comparison of high-frequency electromagnetic scattering prediction methods for jet engines in the time and frequency domains. In particular, hybrid asymptotic modal techniques, and shooting and bouncing ray techniques are compared. It is concluded that ray methods provide an excellent first-order approximation to the RCS (radar cross section) and resultant radar signature for engine ducts. Given that ray methods are applicable to a wide range of geometries, they appear to be an excellent all-purpose method to predict the radar signature of engine ducts. It is noted, however, that there are questions in the prediction accuracy using ray methods that must be considered when calculating the RCS or radar signature of engine ducts.<>