Millimeter and Submillimeter-Wave Reflectionless Filters and Diplexers Based on Silicon Micromachining

Rectangular waveguide is the dominant medium for guided-wave electromagnetic propagation at frequencies greater than 100 GHz and is used up to several terahertz. While rectangular waveguide is low-loss and widely employed for millimeter and submillimeter-wave instruments and test equipment, it is inherently banded-limited by a minimum frequency (the cut-off frequency) and a maximum frequency (due to the requirement for single-mode propagation). Transmission lines, which support TEM modes, offer broadband operation but with a significant increase in loss. Dielectric guide is not as commonly used in the millimeter and submillimeter-wave range because it does not pass DC and the associated difficulties of interfacing it with electronic components and circuitry.

Methods for multiplexing more than one frequency band onto a common TEM medium has potential to address bandwidth limitations exhibited by waveguide-based systems. This issue is of particular interest in instrumentation for metrology, where characterizing such systems require performing measurements over multiple bands, necessitating reconfiguration and recalibration of the measurement system — an inconvenient and time-consuming process that can introduce step-changes in measurements between bands due to dimensional differences or imperfections in the different media.

Multiplexers that can combine two-or-more bands onto a single broadband transmission medium (transmission line) provide an important vehicle for addressing the bandwidth limitations of current millimeter and submillimeter-wave measurement tools. The aim of this dissertation research is to investigate and demonstrate a practical implementation and process for realizing reflectionless filters and multiplexers for the millimeter and submillimeter-wave region of the spectrum using silicon-on-insulator (SOI) as a platform for integration.

In partial fulfillment of doctoral dissertation requirements.
Successfully defended July 2023.
Noah Sauber, Copywrite 2023. All rights reserved.