SOME REMARKS ABOUT THE OBLIQUITY FACTOR USING IN THE KIRCHHOFF DIFFRACTION THEORY

Abstract

In the framework of the work the description of sphere wave filed in the far observation region is discussed. The consideration is based on the decomposition of the wave field over the longitudinal and transverse spatial parameters of the problem in the direction of observation. It is shown that the approximation of a sphere wave by the flat field is correct only if the consideration is conducted in the limit of solid angle. The magnitude of the solid angle, which includes the area of flatness of the spherical wave, is determined using the so-called wave parameters corresponding to the observation area and the illuminated point. The wave field created by a small flat area is defined as a limit case of a superposition field generated by a system of point sources. It is shown that in an observation point the wave field of a small flat area can be characterized by the angle between the area normal and the vector indicting from the given area the observation point. The problem of description of a wave filed in the framework of a small flat aria is also discussed. A new method for deriving of the well-known obliquity factor of the Kirchhoff diffraction theory is suggested.