TABLE OF CONTENTS RF/microwave phased shifters can be classified into two distinct categories, namely, absorption type and reflection type. Absorption-type phase shifters are widely used at RF/microwave frequencies. But reflection-type phase shifters are best suited for mm-wave applications. A phase shifter is the most critical element in electronically steerable-phased arrays for missile tracking radar, covert communications systems, reconnaissance satellites, missile seeker receivers, and unmanned aerial vehicles, where fast target tracking, high-tracking accuracy, and stability are the principal design requirements. DMTL phase shifters incorporating nanotechnology (NT) materials are discussed in great detail, because they offer fast response, minimum insertion, low-power consumption, high reliability and reduced phase errors at mm-wave frequencies. The overall performance of these phase shifters is unmatched by conventional phase shifters using PIN-diodes or FET devices. Design requirements and fabrication processes for a bulk micromachined MEMS phase shifter fabricated on a high-resistivity silicon wafer are summarized. This particular design offers significant reduction in IL, dispersion loss, and power consumption at mm-wave frequencies. Design requirements for the critical elements of a phase shifter, namely, MEMS bridges, dielectric membranes, air gap, 3 dB CPW couplers, dc bias circuits, contact pads, input/output electrodes, and structural materials are defined with emphasis on performance, reliability, and cost. Important properties of potential dielectric substrates, structural materials, and insulation layers widely used in the design of mm-wave phase shifters are summarized. Numerical examples to compute IL, Bragg frequency, periodic spacing between the MEMS bridges, actuation voltage, phase delay, phase shift, and CPW transmission-line parameters are provided for...
