STUDY OF HIGH FREQUENCY FIELDS IN TWO DIMENSIONAL CASSEGRAIN AND GREGORIAN FOCUSSING SYSTEMS

Abstract

Focused electromagnetic waves have appli cations in many areas. such as mIcrowave antennas and integrated optical systems etc. Asymptotic ray theory (ART) or t he geometrical optics (GO) approximation is a powerful tool for evaluating high frequency fields in homogeneous and inhomogeneous medium but it fails in the vicinity of caustic. Maslov's method combines the simplicity of asymptotic ray theo ry and generality of Fourier transform method. This is achieved by representing the geometrical optics fields in terms of mixed coordinates consisting of space coordinates and wave vector coordinates. High frequency field expressions valid around focal regions of two dimensional Cassegrain and Gregorian dual reflector microwave antennas are derived using Maslov's method. The reflectors ma terials composed of perfect electric conductor (PEC), perfect electromagnetic conductor (PEMC) and chi ral nihili ty coated P ElVIC are chosen for the study of field behavior around caust ic region of these systems. umerical computations are used to evaluate field patterns around the caust ic of dual reflector microwave antennas. To establish validity of lVIaslov's method the results of cylindrical parabolic reflector based on Maslov's method are compared with the results obtained using Kirchhoff 's approximation. The results are found in good agreement. The field reflected from both PEMC and chiral nihility backed by PEMC interface, contains both co-polarized and cross-polarized components. Dependence of co-polarized and cross-polarized field components for different values of admittance parameter of PEMC has been studied