Purpose This paper aims to design a radio frequency micro-electro-mechanical system (RF MEMS)-based phase shifter using chamfered coplanar waveguide (CPW) transmission line (t-line) with open-circuit interdigital metal–air–metal (ID MAM) capacitors. Design/methodology/approach The proposed phase shifter achieves maximum differential phase shift with low loss at Ku band. The phase shifter is built with one switchable fixed-fixed beam (MEMS switch) on chamfered CPW t-line in series with two planar open-circuit ID MAM capacitors. An equivalent circuit model for the proposed phase shifter is derived, and its parameters are extracted using an electromagnetic (EM) solver. Findings The MEMS switch is actuated using an electrostatic method with the calculated residual stress of 44.26 MPa. The fabricated phase shifter exhibits low insertion loss, close to 0.14 dB at 17 GHz, with the maximum phase shift of 15.06°. The return loss is greater than 23 dB between 12 and 18 GHz. Originality/value This phase shifter presents a promising solution for low loss applications in the Ku band with a maximum phase shift. As the maximum phase shift of 15.06° is achieved for a unit cell with low insertion loss, the phase shifter is found to be feasible for modern electronically tunable phased arrays used for satellite communication and radar systems.