Asymptotic near-to-far-zone transformation for periodic conformal antennas embedded in canonical structures.

摘要

Conformal antennas are important to the aerospace community because of their aerodynamic characteristics and their versatility for electronic scanning. Computational electromagnetic methods such as the Finite Element-Boundary Integral method have been used extensively to obtain estimations of radiation and scattering performance of antennas on planar, elliptical and prolate spheroid surfaces. Typically, in formulating these methods, either an infinite structure approximation or reciprocity has been used to accomplish the near-to-far-zone transformation. At times, the need for such transformation has been ignored all-together. In cases where a Green's function--that enforced cylinder boundary conditions--was used, calculations of the far-zone field in the paraxial region were inaccurate. Several researchers have been working in obtaining integral solutions that overcome the problems in the paraxial and shadow zone using GTD and UTD techniques.; In this dissertation, an asymptotic periodic dyadic Green's function will be derived. A different asymptotic approximation for the periodic Green's function will be used to accomplish the near-to-far-zone transformation. This results will be validated by testing expression for large radii against similar results for planar structures.