Integral equation analysis of composite bodies of revolution and arbitrary surfaces with application to cavity-backed antennas

A formulation is developed to treat radiation from structures consisting of conducting and/or dielectric bodies of revolution (BOR) in the presence of multiple arbitrarily shaped three dimensional objects. A set of integral equations is developed on the surfaces of the combined structure using the electromagnetic boundary conditions. The resulting integro-differential equations are solved using the method of moments. On the BOR, harmonic entire domain expansion functions are used for the circumferential dependence, while overlapping subdomain functions are used to model the axial curvature. The arbitrarily shaped portions of the structure are modeled wing triangular surface patch basis functions. The resulting system matrix has a partial block diagonal nature which provides a more economical solution for structures which have some rotational symmetry. The accuracy of the BOR and arbitrary surface formulation is verified using several different approaches. The self-consistency method is used to verify the analysis for both perfectly conducting and dielectrically loaded structures. Special emphasis is placed on a unique cavity-backed antenna that is fed by large aperture patches. Numerical results are presented and compared to radiation pattern measurements performed on these antennas with very good agreement being obtained. An approach for solving the problem of junctions between bodies of revolution and arbitrary surfaces is investigated and shown to be accurate for some cases.