This chapter discusses the basic components of a wireless system and ways of obtaining flexible and stretchable versions of these components. The latest research and development in wireless systems aims at developing wireless power transmission links. Free-form antennas coupled with free-form radio frequency circuits can produce completely flexible, stretchable wireless systems. Transistors used in commercial radio frequency circuits can be fabricated using two approaches: field-effect transistors (FETs) or bipolar junction transistors (BJTs). The chapter also discusses the use of spring structures to obtain stretchable antennas. The conductive polymers can be used to obtain stretchable antennas,as demonstrated using composites of silver nanoparticles with styrene-butadiene-styrene, and silver nanowires with PDMS. The chapter investigates ways of obtaining flexible and stretchable silicon-based circuits. It presents an overview of fabrication techniques. Although both transistors can be incorporated into silicon chips using standard fabrication processes, their monolithic integration with state-of-the-art processor technology nodes is challenging.