A Novel Hybrid-Channel Attenuation Measurement System at 50–110 GHz
A novel hybrid-channel attenuation measurement system has been built for the measurement of Vand W-band waveguide attenuators from 50 to 110 GHz. The measurement system combines two single channels of the V and W bands together into one system. The V-band channel is used as the measurement channel and the W-band channel is used as the synchronization channel when the V-band attenuator is measured and vice versa. The measurement system is free of cross talk between the two channels and removes the need for isolators between the local oscillator and the mixer since the RF signal frequencies in the two channels are different. In addition, a compensation module was designed to cancel the self-mixing produced by the W-band mixer at frequencies above 102 GHz. The expanded uncertainty of the system is evaluated to be 0.004-0.08 dB at frequencies ≤102 GHz and 0.005-0.11 dB at frequencies 102 GHz for an attenuation range from 0 to 80 dB.
A millimeter-wave attenuation measurement standard from 26.5 GHz to 40 GHz
A millimeter-wave attenuation measurement standard using the audio frequency substitution method is described in this paper. Attenuation values up to 90 dB from 26.5 GHz to 40 GHz can be measured by this standard. An Inductive Voltage Divider is used as a reference voltage ratio standard at 5 kHz. A dual channel high-sensitivity receiver has been designed to make accurate measurement using a lock-in amplifier. The measurement uncertainty of the new standard is analyzed. The expanded measurement uncertainty of a 0 ~ 90 dB step attenuator at 40 GHz is estimated to be 0.0037 dB ~ 0.011 dB.
Recent Improvements to the UK National Microwave Attenuation Standards
The equipments that have been used in the United Kingdom throughout the last decade for the highest echelon microwave attenuation measurements are approaching obsolescence. To modernize them, two microwave synthesized sources have recently been purchased, and this paper describes five different configurations that have been developed for use with them, namely, a) 0.05-18-GHz parallel 50-kHz substitution system, containing an inductive voltage divider as the reference standard; b) a very low drift series 50-kHz substitution system; c) a series substitution system, employing coherent detection, which has a dynamic range of 150 dB; d) a 0.05-18 GHz-voltage ratio system for the automatic calibration of programmable attenuators; e) a very stable microwave bridge for the precise measurement of waveguide wall loss.