▎ 摘　　要

Ballistic transport through an impurity-free section of the Corbino disk in graphene is investigated by means of the Landauer Bintiker formalism in the mesoscopic limit. In the linear-response regime the conductance is quantized in steps close to integer multiples of 4e(2)/h, yet Fabr) Perot oscillations are strongly suppressed. The quantization arises for small opening angles theta < pi/3 and large radii ratios R-2/R-1 greater than or similar to 10. We find that the condition for emergence of the n-th conductance step can be written as root n theta/pi << 1. A brief comparison with the conductance spectra of graphene nanoribbons with parallel edges is also provided.