In this paper, the design of a linear array of slots is presented at 38 GHz. The array is fabricated with a total number of 24 slots, 12 on each broad side wall of a WR22 rectangular waveguide, to form an omnidirectional azimuth radiation pattern. The offsets of the individual slots are calculated for two cases: when all slots are uniformly excited and when Dolph-Chebyshev synthesis method is used to achieve a radiation pattern with low sidelobe level in elevation plane. The measured results are also compared with those simulated by CST STUDIO SUITE.