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 new synchronous method for attenuation measurement system
Audio frequency substitution with inductive voltage divider (IVD) as reference standard is the most important attenuator calibration system in which a lock-in amplifier is widely used as phase sensitive detector. In order to obtain synchronous signal for lock-in amplifier, a new simple system structures with good stability was developed in NIM (China). Its principle and experiment data are discussed in the paper.
Attenuation and ratio&#8212;National standards
In national standards laboratories, the popular attenuation measurement techniques are: RF, IF, vector IF, and AF substitution; power ratio, voltage ratio, time-interval ratio, and six-port methods; and a procedure that employs a Josephson junction in a superconducting ring. These nine techniques are briefly described, the dynamic ranges and accuracies achieved with them are reported, and their relative merits are discussed. The later sections are devoted to: attenuation measurement techniques used in industry and elsewhere, voltage doubling circuits, attenuation traveling standards, errors and uncertainties associated with attenuation measurements, and international attenuation comparisons. An analysis of the results obtained in four recent international comparisons is included.