Abstract: The bandwidth of conventional 4 ports hybrid-ring coupler is restricted to 10% to 20%. In order to extend the usable band, a modified hybrid-ring coupler is proposed. By adding an extra isolated arm, the functional bandwidth covers the whole W-band. Besides, a chamfer in the input arm is introduced to increase the output isolation. 3D EM simulation results show that, from 75 GHz to 110 GHz, less than 0.07 dB amplitude difference and less than 0.37 degree phase difference is achieved. Compared with no chamfer 5 ports hybrid-ring, the isolation between the two output ports of the modified structure is more than 15.07 dB. The new design could be applied in W-band balanced modulator and other power dividing situation.