Analysis of the Fields in Two Dimensional Cassegrain System

Progress in Electromagnetics Research-pier, 2008

Method proposed by Maslov has been used, to remedy the problem of geometrical optics, for a two dimensional Perfect electromagnetic conductor (PEMC) Gregorian system. It generates an integral form of solution near the caustic that can be evaluated analytically/numerically, or with uniform asymptotic techniques. Away from the caustic it recovers the geometrical optics field. Numerical computations are made to calculate the field around the caustic of a Gregorian system.

2011

A two dimensional cassegrain system is analyzed at high frequency for its focal region field, where its main parabolic reflector is coated with chiral medium. Maslov's method is used because the Geometrical Optics approximation fails at the focal point. Field's patterns are numerically calculated and the results are shown graphically. The effects of thickness, chirality parameter and permittivity of the chiral layer on the focal region field are analyzed. Simple dielectric coating's problem is discussed as a special case of this problem.

Journal of Electromagnetic Waves and Applications, 2008

High frequency field expressions for a two dimensional reflector are derived. The reflector is placed in a homogenous and reciprocal chiral medium. Since geometrical optics fails at caustics so Maslovs method has been used to find the field expressions which are also valid around caustics. Examples of parabolic and circular reflectors have been considered.

Progress In Electromagnetics Research M, 2011

This paper presents the electromagnetic field expressions for 3D cassegrain system embedded in a bi-isotropic chiral medium. Mathematical formulation of Maslov is used to find the field expressions in the focal region. Effect of chirality (both the week and strong) on focal region fields is analyzed. It is seen that when the chirality effect is weak (i.e., κ < 1), chiral medium will support positive phase velocity (PPV) for both the left circularly polarized (LCP) and the right circularly polarized (RCP) modes. However for strong chiral medium (i.e., κ > 1), one mode travels with PPV and the other mode travels with negative phase velocity (NPV). The line plots are given to show the behavior of fields in the focal plane of 3D cassegrain system by changing the chirality parameter (κ).

Progress in Electromagnetics Research-pier, 2007

High frequency field expressions for a two dimensional reflector are derived. The reflector is placed in a homogenous and reciprocal chiral medium. Since geometrical optics fails at caustics so Maslovs method has been used to find the field expressions which are also valid around caustics. Examples of parabolic and circular reflectors have been considered.

International Journal of Infrared and Millimeter Waves, 1986

Expressions for the coupling between Gaussian beam modes and the field in a Cassegrain antenna produced by a distant point source are derived. These are then used to obtain certain important parameters relating to the performance of quasioptical systems which are used on radio telescopes. Some simple examples which require a minimum of computations are presented in order to illustrate the method and obtain some insight into the coupling of quasioptical systems to the telescope. Initially only a single fundamental Gaussian mode is considered and this is used to derive the aperture efficiency and defocusing properties of an ideal "Gaussian feed". The results are compared with those known from classical antenna methods and also to some quasioptical results due to Goldsmith. Higher order Gauss-Laguerre modes are then included and used to predict the efficiency of an antenna fed by a corrugated horn. Although the power of the horn field is almost entirely in the fundamental mode significant changes in predicted aperture efficiency result from

Journal of Optics A: Pure and Applied Optics, 2006

In this paper the nullfield method with discrete sources (NFM-DS) is applied to analysis of light scattering by biconcave Cassini-like particles, which can be described as oblate discspheres with central concavities on their top and bottom. As far as we know this is a first attempt to apply a modification of the T-matrix method to model such a nonconvex object.

Journal of the Optical Society of America A, 2013

Simulations of the Huygens, Fresnel, and Rayleigh-Sommerfeld I approximations in the case of free-space propagation of a Gaussian beam are compared with analytical solutions. The most accurate results were obtained by the Rayleigh-Sommerfeld I approximation. The study reveals that the approximations are not uniform throughout the propagation region. While the accuracies of the Huygens and Fresnel methods generally increase as the propagation distance increases, the accuracy of the Rayleigh-Sommerfeld I approximation at first starts to diminish and later recovers as the propagation distance is further increased.

Advanced Microwave and Millimeter Wave Technologies Semiconductor Devices Circuits and Systems, 2010