In momentum, How to define a sheet R in a transmissionline?

In momentum, How to define a sheet resistor in a transmission line. I need this structure: a cpw with a gap, and there is a 20 Ohm sheet resistor in the gap, the cpw is a perfect conductor.

Can I draw a pad in the gap, as R between C| |C , and define its value is 20Ohm in momentum?

Many Thanks!

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