Accuracy of the Leontovich boundary condition for continuous and discontinuous surface impedances

Abstract

The accuracy of the Leontovich boundary condition is estimated for discontinuous impedance surfaces. This is accomplished by comparing the exact solution of a given canonical problem with the Leontovich boundary condition solution. The case of a circularly symmetric cylindrical cross section is considered. The cylindrical cross section can be composed of electrically similar or dissimilar materials so that a continuous or discontinuous surface impedance can be simulated. The index of refraction is chosen as an arbitrary parameter so that a wide range of surface impedances is included. In addition, the radius of the cylinder with respect to wavelength (i.e., ka) is varied to investigate the effect of curvature on the accuracy. Both magnetic line sources and H polarized plane waves are used to illuminate the surface. The error curves which are obtained represent the worst error situation for the chosen problem. One of the significant conclusions from this investigation is the observation that the error is largest at resonance.