This article aims to discuss challenges and performances of a passive load-pull test bench dedicated to the G-band frequencies. The first task of this work is the development of the setup to perform high power generation, impedance generation, and high-power dynamic of measurement. The solution proposed is the association of an external power system of source and detectors, with an integrated synthesizer of impedance. The proposed system requires several analysis steps in order to be validated. On the other hand, special care is dedicated to the calibration of the scalar measurement in the millimeter-wave frequency range. Then, due to the unknown phase at the input and output of the device under test (DUT), scalar measurement can lead to high inaccuracy. Hence, an adaptive calibration is proposed and applied to the measurement of a bipolar transistor at 185 GHz. We highlight the effect of the missing phase information on the accuracy of measurement. Results of the measurement are discussed.