A six-port reflectometer for in-situ monitoring of frequency multipliers

This paper describes a waveguide-based reflectometer designed for in-situ measurement and monitoring of the return loss between adjacent stages in a frequency multiplier chain. The reflectometer is based on a six-port architecture and a prototype instrument operating at V-band (50–75 GHz) is introduced. An in-situ calibration method based on null double injection is discussed and initial measurements to assess the performance of the prototype are presented.