Slot radiators in the broad wall of a rectangular waveguide tuned by perfectly conducting inductive posts

The characteristics of slot radiators in a rectangular waveguide tuned by perfectly conducting inductive posts and excited by the dominant waveguide mode are rigorously determined in this dissertation. The slots are assumed arbitrarily inclined in the broad wall of the waveguide, and radiate in a homogeneous half-space. The posts are assumed uniform along the narrow wall of the waveguide, but are otherwise of arbitrary cross-section and thickness. The effect of waveguide wall thickness is also taken into account in the problem formulation. The radiation pattern in the upper half-space and the Kajfez-Wilton scattering matrix of the three port network comprised of the radiating slot port and the waveguide two-port matrix are accurately computed so that they may be used as inputs in a suitable array design procedure formulated with the slot-post system taken as an array element.; An important outcome of the dissertation is the derivation of exact analytical expressions for the electric and magnetic fields of a rectangular patch of uniform and linear distributions of currents in a homogeneous free space. In addition, efficient decompositions of the waveguide Green's functions and their first and second partial derivatives into singular and bounded parts are obtained. Closed-form integrals of the singular parts over arbitrarily inclined rectangles are also derived with the help of those of the free space Green's functions. These expressions are useful in the accurate computation of the electric and magnetic fields in the source region required for the application of the boundary conditions in the numerical solution of many important electromagnetic field problems, and are used here in the construction of the matrices arising in the Method of Moment solution of the problem of the tuned slot radiators.; The results of extensive numerical experiments involving untuned longitudinal and transverse slots are found to corroborate well with available numerical and experimental data. The convergence of numerical results is established for configurations involving isolated slot, isolated post, and a slot-post pair inside the waveguide. The results obtained in the case of iris-tuned longitudinal and transverse slots show that tuning broad wall slot radiators by posts is a viable procedure to control the amount of radiation. It is also shown how the amplitude of the slot aperture field can be increased and the phase can be controlled by proper placement of posts so that, in particular, a tuned narrow longitudinal slot along the centerline of the waveguide can become an efficient radiator. Results for a two-element array of centered tuned narrow longitudinal slots are also given and discussed.