Hybrid analytical technique for radiating slots in waveguide

A hybrid technique which combines the finite element method with the moment method is proposed for the analysis of radiating slots as used in slotted-waveguide array antennas. It differs from earlier contributions to this topic in that it formulates the field in the slots in terms of a functional, rather than a Green's function or combination of higher order waveguide modes which are generally used in conventional moment methods. It is, therefore, a promising candidate for the analysis of radiating elements of complex shape as used in, for example, circularly polarized and polarization selective slotted-waveguide array antennas. A conventional longitudinal slot in the broad wall of rectangular waveguide and a complex T-shaped slot in bifurcated waveguide have been modeled to demonstrate the validity of the hybrid technique. The numerical results are shown to be in good agreement with those obtained from independently procured theoretical evidence and measurement.