Graduation Year

2006

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Electrical Engineering

Major Professor

Thomas Weller, Ph.D.

Keywords

RF mems, Telemetry, Nano technology, Capacitors, BASK

Abstract

In this work, various components for low power RF telemetry applications have been investigated. These designed, fabricated and tested devices include radio frequency (RF) micro-electro-mechanical systems (MEMS) switches, single-pole-double-throw (SPDT) RF MEMS switches, nano fabricated capacitors and switching devices, and micromachined microstrip patch antennas.Coplanar waveguide (CPW) RF capacitive switches in shunt and series configuration were designed for high isolation, low insertion loss, and fast switching speed. Switches with > 35 dB isolation, < 0.3 dB insertion loss and switching speeds in the 10's of microseconds were fabricated and measured. These switches were packaged using photo-imagable resists and flip-chip bonding techniques. The MEMS shunt switch topology was also implemented into a single-pole-double-throw (SPDT) design by utilizing two such switches in a series and a shunt configuration, offset by a quarter wavelength section to provide a RF shor

t at the input of the shunt switch in the off state. This type of design has the advantage of requiring a simple on-off (0 V and 35 V) bias supply to select the switch state.Also, the use of a focused ion beam (FIB) tool to mill sub-micron gaps in CPW transmission line structures was investigated. Nearly ideal capacitors in the micro- and mm- frequency range with capacitance of 8-12 fF were obtained using this milling technique. The FIB's capability to mill such small gaps at an oblique angle was also utilized to fabricate RF nano switches. These devices were switched with speeds of less than 300 ns with voltages of less than 20 V. Finally, solid state and packaged MEMS switches were integrated into a novel binary amplitude shift keyed (BASK) modulating RF telemetry system to provide the modulation of a redirected 10 GHz continuous wave (CW) signal. A pair of cross-polarized micromachined microstrip patch antennas was used in the system to receive the CW signal and re-transmit th

e modulated signal. A transmission range of over 25 m was demonstrated with the solid state switch reflectenna.

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