A millimeter‐wave cylindrical conformal array with a 120° flat‐top broad beam and a stable 30° downward tilted‐angle is demonstrated, fabricated and measured in this paper. The radiating part consists of eight slotted waveguides, with 32‐element longitudinal slots per waveguide. The feeding network consists of a 1‐to‐8 unequal power divider and a compact phase compensating network, which was designed to provide stable phase differences between the adjacent slotted waveguides for the radiating part. The conformal antenna is wrapped around a cylindrical with a radius of 36.5 mm in the circumferential direction. Measured results show that the beam is covered in H‐plane over a field of view of 120° with a flat‐top, and achieved a stable 30° downward angle in E‐plane. The measured antenna gain was ∼12 dBi with a gain ripple within 1.4 dB. The measured reflection is below −10 dB over the frequency range of 40.25–44 GHz. The proposed new conformal array antenna can be used in millimeter wave wireless local area network. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1666–1671, 2016