Compact KA-band one-port vector reflectometer using a wideband electronically controlled phase shifter

In this paper, the design and implementation of a compact one-port Ka-band (26.5-40 GHz) vector reflectometer or network analyzer (VNA), operating in full Ka-band frequency range, are presented. The design follows that of a recently developed VNA but with the goal of producing a wideband version. The most critical component of this design is a wideband electronically controlled phase shifter, designed using nonuniformly spaced p-i-n diode-loaded slots incorporated in the broad wall of a rectangular waveguide. Nonuniform placement of the slots is shown to significantly reduce unwanted resonances within the operating bandwidth. Also, the new design provides the possibility of using a more accurate three-port $S$ -parameter characterization instead of the previously used two-port approach. The design foundation and measurement results are presented.