In this paper the effect of curvature radius on radiation patterns in multibeam antennas fed by a Butler matrix has been shown. Calculation results taking into account the change of amplitude and phase of the signal received at each radiating element caused by the array curvature for different radii have been presented. A simple compensation technique is studied which allows us to achieve proper radiation patterns by adding phase shifters in outer channels. It is shown that by using this technique we can obtain radiation patterns of conformal antenna arrays which with respect to the side lobes are comparable with planar antenna arrays. Measurement results of a 4times1 conformal antenna array fed by a Butler matrix are presented and agree well with the calculated ones