I. Introduction
A recent research effort in noncooperative target recognition within the Combat ID community involves the development of a synthetic target signature database for target classifiers. For various technical reasons, a synthetically generated database is regarded as the most practical way of fielding an operational target classifier system [1]. Synthetic target signatures are computed using high-frequency electromagnetic radar cross-section (RCS) prediction codes. There has been a great deal of research activities in recent years focusing on cavity RCS modelling of aircraft duct/engine interface. It is known that the inlets of aircraft can produce a significant contribution to the overall RCS of an aircraft. Therefore, cavity RCS computation should be an integral part of the synthetic signature modelling process of aircraft.