Scattering from a cylindrically conformal slotted waveguide array antenna

A numerical method is developed to investigate electromagnetic scattering by a cylindrically conformal waveguide-fed slot array. The problem is first formulated in terms of integral equations using the equivalence principle. The integral equations are then solved using the method of moments (MoM) in conjunction with global sinusoidal basis functions and Galerkin´s testing procedure. The MoM solution requires the evaluation of the generalized admittance matrices involving various dyadic Green´s functions. The slow convergence of the series associated with the summation of waveguide modes is accelerated using the Kummer transformation and the slow convergence of the series associated with the summation of the exterior modes is avoided by using the asymptotic solutions with proper treatment for singular integrals. The evaluation of the excitation vector and scattered field is also accelerated using Watson´s transformation and asymptotic solutions. Numerical results are presented to illustrate the scattering characteristics of the cylindrically conformal waveguide-fed slot arrays, such as the effects of curvature, slot thickness, and waveguide termination on the radar cross section (RCS) of the arrays