This book presents the design of different switching and resonant devices using the present state-of-the-art radio frequency (RF) micromachining (MEMS) technology. Different topologies of MEMS switches have been discussed considering optimum performances over microwave to millimeter wave frequency range. Wide varieties of micromachined switching networks starting from single-pole-double-throw (SPDT) to single-pole-fourteen-throw (SP14T) are discussed utilizing vertical and lateral actuation movements of the switch. Different transduction mechanisms of micromachined resonators are highlighted that includes capacitive, piezoelectric, and piezoresistive types. The book provides major design guidelines for the development of MEMS-based digital phase shifters, tunable filters, and antennas with extensive measurement data. Apart from the radio frequency (RF) requirements, an extensive guideline is given for the improvement of the reliability of micromachined switches and digital phase shifters where multiple switches are operating simultaneously. It takes multiple iterations and extensive characterizations to conclude with a reliable MEMS digital phase shifter, and these aspects are given one of the prime attentions in this book. Detailed performance analysis of metamaterial inspired MEMS switches is then discussed for application in millimeter wave frequency bands up to about 170 GHz. The book concludes with future research activities of RF MEMS technology and its potential in space, defense, sensors, and biomedical applications.