The propagation constant of coaxial offset shorts with rough surfaces

Offset short calibration schemes for vector network analyzers require the exact knowledge of the propagation constant of the offsetting lines. The propagation constant is difficult to compute from first principles and thus a method to indirectly determine the propagation constant is presented. At 50 GHz, the method achieves improvements of accuracy of at least 0.013 in linear S-parameters for a 2.4mm offset short with length 13 mm.