electromagnetic-circuit co-simulation in cst

any body know how to define a block with pi phase shift?

or how i can simulate this structure(attached) with cst?fig 1 in paper "Field Displacement in a Traveling-wave Ring Resonator Meta-structure"\Toshiro Kodera1, Dimitrios Sounas2, Hoang Van Nguyen2, Hadi Razavipour 2, and Christophe Caloz 2,2011