The Use of Inhomogeneously Loaded Rectangular Waveguide to Overcome Grating Lobes and Distribution Taper Limitations in Transverse Slot Arrays

The ability to analyse transverse slots in inhomogeneously loaded rectangular waveguide creates new design possibilities for slotted waveguide arrays. In order to demonstrate some of these advantages, this paper presents results which show that transverse slot arrays in inhomogeneous rectangular waveguide can be designed which do not have grating lobes in their radiation patterns, and do not suffer from the same distribution taper limitations as similar arrays of homogeneous waveguide transverse slots. The self-properties of individual transverse slots in inhomogeneously loaded rectangular waveguide are computed with a moment method code and compared to measured data. Design equations with which the length and offset of each slot in a resonant linear array may be calculated, were derived. The design procedure includes the effect of external mutual coupling.