Integrated design of a compact Ka-band one-port vector reflectometer

In this paper, an integrated design of a compact one-port vector millimeter wave reflectometer or network analyzer (VNA), operating in the Ka-band (26.5-40 GHz) frequency range is presented. The design follows that of a recently-developed VNA, but with the goal of incorporating its critical components into one integrated system so as to make it smaller, improve its measurement accuracy and source stability, while incorporating on-board control and data collection approach. The most critical high-frequency component of this design is an electronically-controlled phase shifter, designed using sub-resonant PIN diode-loaded slots incorporated in the broad wall of a rectangular waveguide. Using a non-uniform spacing scheme used in the placement of the slots is shown to significantly reduce unwanted resonances. In addition, slot-coupled rectangular waveguide-tee configuration is used for the standing-wave probe section of this reflectometer which is incorporated into the phase shifter on the same high-frequency printed circuit board (PCB). Finally, this new design provides the possibility of using a more accurate three-port S-parameters characterization instead of a two-port characterization. The design foundation and some results of extensive simulations are shown in this paper.