Abstract: In this paper, a new type of rectangular waveguide-SIW Converter is proposed . The direction of the electric field inrectangular waveguide can be transmitted in SIW by the antipodal finline converter. Through the help of HFSS simulation , thestructure has been optimized between the range of 30G to 40G .Insertion loss less than 0.13dB, return loss is better than 20dB. Backto back insertion loss less than 0.22dB, return loss better than 20dB, the relative bandwidth is more than 25%.