Analysis of electromagnetic backscatter from an inlet cavity configuration

The radar cross secction of jet engine configurations on modern aircraft is a most perverse problem analytically. An ability to predict the radar cross section of loaded cavity structures, even when such structures are only very crude models of the actual engine, has been seriously lacking. At the same time it is well known that above a certain spectral range the engine configuration largely controls the radar cross section of the aircraft over a large span of noise and often stern aspects. Recently, the radar signal modulation produced by the engines has become of important analytical concern. This report is separated into two parts. Part I, Ray Analysis of EM Backscatter from a Cavity Configuration contains the major thrust of our research and basically details an asymptotic frequency domain analysis of various loaded cavity structures. Part II, Canonical Response Waveforms of Finite and Open Circular Waveguides is essentially a time domain analysis of the same types of problems. The parts are interrelated in the sense that results from one are used in the other. For example, Part II reproduces a portion of the exact Wiener-Hopf computations for an open circular waveguide. These results were used to verify a portion of the theory in Part I. Conversely, frequency computations from the analysis in Part I are used in Part II as part of a Fourier synthesis procedure to obtain canonical response waveforms.