Complex Transmission Coefficient Measurement at 50–110 GHz With Hybrid-Channel Measurement System

A hybrid-channel attenuation measurement system has been built for the measurement of waveguide variable attenuators at V- and W-band s, from 50 to 110 GHz. The hybrid-channel system consists of the V-band and W-band heterodyne channels. One channel is used as the measurement channel, while the other is used as the synchronization channel. The system eliminates the cross-leakage between the channels completely, as the radio frequency signal frequencies in the two channels are different from each other. The experiments show that the system has good performances in measuring phase shift as well. Furthermore, the system can be used as a primary standard of the complex transmission coefficient. A comparison measurement with the vector network analyzer was carried out. The results show that the proposed system has much smaller uncertainties both in the magnitude and in the phase. The measurement uncertainty of attenuation is 0.004-0.11 dB, and the phase shift uncertainty is less than 1° at frequencies from 50 to 100 GHz and the dynamic range from 0-80 dB.