CAN BUS cable Shielding effectiveness
The coax picture and equations are refered to unbalanced source/load and coax. With CAN you have balanced, twisted pair configuration, where noise is picked up equaly in both conductors, therefore noise voltage is eliminating each other. No current is passing in the shield, the shield is just a Faraday cage screening twisted pairs from noise. It has to be on earth potential in one point. You have best results if the shield is tied on the ground on both sides, but usually we tend not to connect shiled on both sides, as the ground loop current can flow trough shield - this if ground potentials of both sides is different.