This document describes a waveguide with a zigzag for suppressing grating lobes. An apparatus may include a waveguide with a zigzag waveguide channel to suppress grating lobes in diagonal planes of a three-dimensional radiation pattern. The waveguide includes a hollow channel containing a dielectric and an array of radiation slots through a surface that is operably connected with the dielectric. The hollow channel has a zigzag shape along a longitudinal direction through the waveguide. The zigzag waveguide channel and radiation slots configure the described waveguide to suppress grating lobes in an antenna radiation pattern. This document also describes a waveguide formed in part by a printed circuit board to improve the manufacturing process.