Flexible electronic circuits can be easily integrated with large area (>10m aperture), inflatable antennas to provide distributed control and processing functions. Flexible electronic circuits can also perform dynamic antenna sub-arraying and gain pattern reconfiguration for active phased-array antenna (PAA) and thus significantly enhance the reliability of NASA's space radar systems. However, existing flexible electronics are based on organic semiconductor materials that have carrier mobility four orders of magnitude lower than conventional single crystal silicon. Such low carrier mobility limits the operating speed of flexible electronics to a few kilohertz and thus makes it unsuitable for multi-GHz RF antenna applications. The proposed research aims to develop a printable silicon nano-FET with high carrier mobility of over 400 cm2/V·s. Such high carrier mobility provides an unprecedented opportunity to achieve flexible electronics with high operating frequency of over 40GHz. We will also develop procedures for printing of conducting interconnect wires using carbon nanotubes, which is critical for printing semiconductors. Based on our past experience on printable silicon nano-FET and printable carbon nanotube wires, the high-speed flexible electronics are expected to be integrated with large-area, inflatable radar antennas and achieve smart antenna systems for high performance and reliable space operations.