Transverse radiation pattern of a slotted waveguide array radiating between finite height baffles in terms of a spectrum of two-dimensional solutions

In arrays of waveguide fed slots, the periodicity of the slots causes grating lobes off the principal planes, referred to as second-order beams. To suppress these lobes, parallel plates (baffles) on both sides of the array can be used. In this paper, a linear array of longitudinal slots radiating between such baffles of finite height is analysed. The three-dimensional (3D) field problem is reduced to a two-dimensional (2D) problem via a Fourier transform. An integral equation for the 2D problem is developed and solved. The 3D radiation pattern, including the effect of a finite ground plane outside the baffles, is calculated from the 2D solutions. Results for various baffle dimensions, showing the attenuation of second-order beams, are presented and the computed solution has been verified by measurements