Abstract: An RF phase shifter circuit includes first and second RF ports, and a switch circuit comprising a plurality of micro-electro-mechanical (“MEM”) switches responsive to control signals. The switch circuit is arranged to select one of a plurality of discrete phase shift values introduced by the phase shifter circuit to RF signals passed between the first and second RF ports. The circuits can be connected to provide a single-pole-multiple-throw (SPMT) or multiple-pole-multiple-throw (MPMT) switch function. The phase shifter circuits can be used in an electronically scanned array including a linear array of radiating elements, with an array of phase shifters coupled to the radiating elements. An RF manifold including a plurality of phase shifter ports is respectively coupled to a corresponding phase shifter RF port and an RF port. A beam steering controller provides phase shift control signals to the phase shifters to control the phase shift setting of the array of the phase shifters.