Radiation from Slots on Cylindrical Bodies Using Geometrical Theory of Diffraction and Creeping Wave Theory

Constantine A. Balanis

Jan 1970 · National Aeronautics and Space Administration

About this ebook

A hybrid solution employing wedge diffraction and creeping wave theories is used to compute the radiation patterns of axial and circumferential slots in the principal planes (equatorial and elevation) on conducting cylinders of finite and infinite lengths. The slots are excited by parallel-plate waveguides operating in the TEM and TE10 modes. For the equatorial-plane pattern, the total field in the lit region is obtained by the superposition of two fields, that is, the wedge-diffracted and the creeping-wave fields. The wedge-diffracted field is obtained by approximating the parallel-plate --cylinder geometry with two wedges, each formed by a wall of the waveguide and a tangent plane to the cylinder surface at the edge point. The creeping-wave contribution is obtained by the use of diffraction and propagation coefficients of waves traveling around conducting curved surfaces. The total field in the shadow region is obtained solely from the creeping-wave contribution. For the elevation-plane pattern, wedge diffraction techniques for the entire pattern are employed. The main advantages of the present technique are that it can be applied to geometries where modal solutions are not possible, in numerical ranges where the convergence properties of modal expansions are relatively poor, in parametric design problems since the contribution from each field is separated, and in the analysis of antenna with finite physical sizes.