Advances in PAA Technology for MIR

Advanced millimeter-wave imaging technology is under development at UC Davis in support of Microwave Imaging Reflectometry (MIR). Foremost of these new technologies are microelectromechanical systems (MEMS) delay lines configured as a beam shaping phased antenna array (PAA). For plasma use, these are configured as an artificial lens with a voltage-controllable focal length for launching the MIR probe or illumination beam. Control of the ``lens'' permits the curvature of the illumination beam to be matched to that of the target plasma over a wide range of frequencies. An NSTX design will be presented along with preliminary testing results at a reduced frequency of 28 GHz for proof-of-principle testing.