The Analysis of Hybrid Reflector Antennas and Diffraction Antenna Arrays on the Basis of Surfaces with a Circular Profile

Abstract

Science achievements in methods of processing of the radar-tracking information define directions of development of antenna systems. These are expansion of aims and functions of antennas, achievement of optimal electric characteristics with regard to mass, dimensional and technological limits. Hybrid reflector antennas (HRA’s) have the important part of the radars and modern communication systems. In HRA the high directivity is provided by system of reflectors and form of the pattern of the feed, and scanning possibility is provided by feeding antenna array. Artificial network, generic synthesis and evolution strategy algorithms of the phased antenna arrays and HRA’s, numerical methods of the analysis and synthesis of HRA’s on the basis of any finite-domain methods of the theory of diffraction, the wavelet analysis and other methods, have been developed for the last decades. The theory and practice of antenna systems have in impact on the ways of development of radars: radio optical systems, digital antenna arrays, synthesed aperture radars (SAR), the solid-state active phased antenna arrays (Fourikis, 1996). However these HRA’s has a disadvantage – impossibility of scanning by a beam in a wide angle range without decrease of gain and are worse than HRA’s on the basis of reflector with a circular profile. In this antennas need to calibrate a phase and amplitude of a phased array feeds to yield a maximum directivity into diapason of beam scanning (Haupt, 2008). Extremely achievable electric characteristics HRA are reached by optimization of a profile of a reflector and amplitude-phase distribution of feeding antenna array (Bucci et al., 1996). Parabolic reflectors with one focus have a simple design, but their worse then multifocuses reflectors. For example, the spherical or circular cylindrical forms are capable of electromechanical scanning the main beam. However the reflectors with a circular profile have a spherical aberration that limits their application. The aim of this article is to elaborate the combined mathematical method of the diffraction theory for the analysis of spherical HRA’s and spherical diffraction antenna arrays of any electric radius. The developed mathematical method is based on a combination of eigenfunctions/geometrical theory of diffraction (GTD) methods. All essential characteristics of physical processes give the evident description of the fields in near and far antenna areas.