Ka-Band Vector Reflectometer Based on Simple Phase-Shifter Design

An automated handheld simple vector reflectometer design for complex-reflection-coefficient measurements at 35.5 GHz (Ka-band, 26.5-40 GHz) is presented. The proposed reflectometer is based on a standing-wave voltage measuring device and an electronically controlled and custom-designed millimeter-wave phase shifter. The phase shifter consists of p-i-n diode-loaded subresonant slots cut into the wall of a Ka-band waveguide. This paper describes the design of the phase shifter and the overall reflectometer. A comparison of the measurement results, for several loads, using this reflectometer and an Agilent E8364B performance network analyzer is also presented showing the measurement accuracy of the proposed reflectometer. Finally, the utility of this reflectometer for imaging complex composite structures, incorporating a high-resolution synthetic aperture imaging technique, is also demonstrated.