In this paper a cavity backed slot antenna (CBSA) has been designed and fabricated in ridge gap waveguide technology. To increase the bandwidth of cavity backed slot antenna, two perturbations have been made at to corners of the RGW cavity. The perturbations cause to deviation of resonance frequencies of two degenerate TM100 and TM010 modes . The slot is embedded at the optimum place on the top plate of RGW cavity to create the radiation performance. The cavity is fed by a RGW which has been connected to WR62 waveguide port via staircase transition. parametric study is done to obtain optimum dimensions and position of slot, perturbation and transition using HFSS software. The simulation results show about 10 % bandwidth for S11
)