The amplitude (red line) and propagation phase (blue line) of the transmitted RCP electric field as a function of W_l upon LCP incidences at 8.6 GHz. The introduced PB phase [green line in (a) and purple line in (b)] causes the transmission phase of RCP to be zero [parallel dashed lines in (a)], and to be π [parallel dashed lines in (b)]. 32 pairs of copper/FR4 layers and 2 mm thick FR4 substrate are used for the RHMM meta-atom, while the other geometrical parameters are the same as those in Fig. 2.