Higher order ferrite junction switch for radiometer calibration

In microwave remote sensing radiometers, calibration switches are needed in the application of the most internal calibration references. Very low insertion loss is beneficial in view of low receiver noise and good radiometric resolution (NEDT). Very low insertion loss can be achieved with ferrite junction switches. In developing millimeter wave ferrite junction switches, however, the small dimensions of the ferrite becomes a challenge. Targeting towards W band (89 GHz), two frequency-scaled switches at Ka band (36.5 GHz) have been developed in the current work. One of the switches applies higher order mode operation, resulting in larger ferrite dimensions. A reference switch to apply dominant mode operation has been developed as well. In this study, the feasibility of both dominant mode and higher order mode operation switches has been confirmed and good compliance between simulations and measurements observed. The switches have average insertion losses of 0.85 dB and 0.3 dB over 1.0 GHz and 4.5 GHz, respectively.