The original scale changing technique is applied to the electromagnetic modeling of MEMS-controlled phase-shifters used in reconfigurable reflectarrays. The phase shift is derived from the simple cascade of networks, each network describing the electromagnetic coupling between two scale levels. This technique allows computing quasi-instantaneously the 1024 phase-shifts achieved by 10 RF-MEMS switches distributed on the surface of the phase-shifter. Moreover sensitivity as regards of RF-MEMS switches losses was discussed. Experimental data are given for validation purposes