Cavity Radar Cross Section Prediction

Alternative models are discussed for the determination of the interior irradiation contribution to the radar cross section (RCS) of open-ended cavities. Typical applications of practical interest include radiation field prediction of open-ended waveguides and signature prediction of jet engine air intakes and exhaust outlets. It is shown and explained why the classic perfectly conducting (PEC) ground plane (GP) model sometimes predicts measured cavity RCS very poorly. Examples where PEC GP model predictions are 5 dB or more off are provided. Verifications that the used PEC GP model is correctly implemented are provided. A physical optics based modification of the classic PEC GP model is provided and explained. A novel model where the cavity aperture forms an opening in an infinite radar absorbing (IBC) screen is proposed verified and validated. The IBC model resembles the common experimental set-up, and poses an efficient novel halfspace type replacement model approximating a full space setting. The modified PEC GP model or the IBC model can be used interchangeably for cavities with electrically large apertures.