G.T.D. analysis of the near-field patterns of pyramidal horns

A technique of analysing the principal-plane near-field patterns of pyramidal horns excited in the dominant mode based on the uniform geometrical theory of diffraction (u.g.t.d.)1, 2 is presented in this paper. The geometrical-optics field is derived by approximating the horn as a quasipyramidal horn waveguide.9 Numerical computations of the near-field amplitude patterns of a typical pyramidal horn based on the g.t.d. technique detailed here well correlate with the measured patterns, justifying the validity of the analysis presented. Further, the analysis presented is valid for any arbitrary field point (located in the principal planes) so that pattern computation is possible in the near field or in the Fresnel zone or in the far field.