A compact, light-weight, low-power MMW radar system operating at 240 GHz is introduced to enable autonomous navigation of micro robotic platforms in complex environments. The short wavelength at the operating frequency band (1.25mm @ 240 GHz) enables implementation of the radar front-end components on a silicon wafer stack using micromachining techniques.
This work presents the design, fabrication technology, and measurement methodology of components for the micromachined MMW radar and the phenomenology of such radars in indoor environments. Novel passive structures are developed to realize a fully micromachined radar front-end. Low loss cavity-backed CPW (CBCPW) lines (0.12 dB/mm @ 240 GHz), broadband transitions from the CBCPW line to rectangular waveguide (IL13 dB; BW: 39%), MMIC chip integration transitions, and waveguide directional couplers are designed to fully integrate active and passive components of the radar. Also a membrane-supported miniaturized-element FSS image-reject filter (IL25 dB in the stopband) is developed for MMW radar applications. The structures are designed compatible with micromachining technology and optimized for minimum insertion loss. The designed components are then realized over a two layer stack of silicon wafers. Multi-step structures are realized on one of the wafers and the membrane-supported features are implemented on the other wafer. A novel multistep DRIE technique is utilized to enhance the profile quality of the fabricated structures. Measurement techniques are developed to enable accurate and repeatable characterization of the on-wafer components at MMW and higher frequency bands. A novel waveguide probe S-parameter measurement technique is introduced for non-contact characterization of the multi-port components using a two-port network analyzer.
To examine the utilization of the proposed 240 GHz radar for collision avoidance and building interior mapping applications, the interaction of electromagnetic waves with objects in the indoor environments is investigated. An instrumentation radar is utilized to collect backscatter data from corridors in an indoor setting. The collected data is used to form radar images for obstacle detection. The radar images are co-registered in a global coordinate matrix to form a complete map of the interior layout. Image processing techniques are used to enhance the final layout map.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107273/1/moallem_1.pd
