A new type of star coupler for single-mode optical fibers is proposed. The geometrical configuration of the coupler is intended to be a tapered cylindrical ring structure. A numerical analysis yields the evolution of the light distribution along the coupling region and the spectral characteristics of the coupler. For a star coupler with 8 x 8 ports and a length of 14 mm a spectral width of 90 nm was calculated, if an additional loss of 0.5 dB is tolerated.