A 194–214-GHz Single-Sideband Mixer With Vertical and Inline Transitions Suitable for Linear Array Applications

A 194–214-GHz single-sideband (SSB) Schottky diode-based subharmonic mixer is newly presented for linear array applications. To realize 3-D integration, a vertical transition is adopted, which also acts as an IF-LO duplexer and an impedance transformer. A waveguide filter is integrated into the mixer for high image rejection, and an inline transition performs efficient mode conversion and impedance matching between the waveguide filter and the diode. The proposed mixer is more suitable for repeated arrangement in a linear array than conventional mixers with orthogonal configuration. A four-element mixer array is fabricated and measured. The array’s minimum SSB conversion loss (CL) is 8.1–10.4 dB from 194 to 214 GHz, the CL difference between elements is less than 1.3 dB, and the sideband rejection ratio is better than 30 dBc.