E-POLARIZED SCATTERING FROM A CONDUCTING RECTANGULAR CYLINDER WITH AN INFINITE AXIAL SLOT FILLED BY A RESISTIVELY COATED DIELECTRIC STRIP

The potential use of resistive films for damping the resonance spikes observed in the radar cross section (RCS) spectrum of a partially open rectangular cavity is investigated using a recently developed finite-difference time-domain (FDTD) method that utilizes the resistive sheet boundary condition for the modeling of resistive films. Backscattering data obtained in the first resonant region for an E-polarized plane wave normally incident into the slotted side of the cavity are presented. It is shown that resonance behaviors can be eliminated completely with a low-resistance film (e.g., R(S) = 188.5-OMEGA) which attenuates significantly the impinging wave. Poorer resonance damping performance is observed as the film resistance increases to 754-OMEGA because more of the field is allowed to penetrate into the cavity. For the latter case, the presence of the resistive film lowers the Q-factor of the slotted cavity such thal the resultant resonance spectrum is lower in strength and broader in bandwidth.