Development of MEMS microwave switches with application to reconfigurable integrated antennas.

摘要

In this thesis, a design methodology for microelectromechanical system (MEMS) shunt switches is presented and implemented. A four mask, surface-micromachining procedure for fabricating MEMS devices is demonstrated, as is the use of hexamethyldisilizane (HMDS) as an anti-stiction surface treatment when releasing suspended MEMS structures. It is shown that the use of HMDS significantly increasing the number of usable switches by reducing stiction and resulting in a process yield of 75%. As well, the performance of a MEMS shunt switch is presented and compared with simulated results. Agreement between simulation and measured results was found to be quite good. An insertion loss of 0.25 dB is observed in the off-state between 10–20 GHz. In the on-state, an isolation of 5 dB is demonstrated at 10 GHz, rising to 10 dB at 20 GHz. The shunt switches were designed to operate between 10–20 GHz in a coplanar waveguide (CPW) regime.; The MEMS switch capability developed herein is also applied to a novel coplanar patch antenna configuration in order to achieve adaptive radiation characteristics. The dimensions of the antenna are adjusted by selectively contacting adjacent islands using cantilevers, thereby altering the phase of the radiated signal. The final patch design shows a simulated phase shift of 70 degrees in the radiated signal between 28–32 GHz.