Abstract: A new waveguide which can change the wide wall of a rectangular waveguide into a symmetric arc wall is named as a camrectangular waveguide.Comparing to sectoral waveguide,the new waveguide has the same voltage characteristics and is easier to be produced and fixed.An approximate formula of the dominant mode fields and the normalized conductance of a longitudinal resonant slot cut in the curved wall of a camrectangular waveguide are given.A resonant slot linear array in C & X band is designed,in which the slot voltage distribution is equiphase and the input is matched.The input voltage stationary ware ratio and the H plane pattern of the antenna are measured.The experimental results show the conformance with theoretical results.